Internet Draft L.A. Sanchez, Megisto
draft-ietf-ipsp-spp-01.txt M.N. Condell, BBN
Expires July, 2002 January 29, 2002
Security Policy Protocol
Status of this Memo
This document is an Internet-Draft and is in full conformance
with all provisions of Section 10 of RFC2026.
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Abstract
This document describes a protocol for discovering, accessing and
processing security policy information of hosts, subnets or networks
of a security domain. The Security Policy Protocol defines how the
policy information is exchanged, processed, and protected by clients
and servers. The protocol is extensible and flexible. It allows the
exchange of complex policy objects between clients and servers.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Definitions. . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Policies . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. SPP Message. . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 SPP Message Format . . . . . . . . . . . . . . . . . . . . 7
3.2 SPP Payloads . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.1 Query Payload. . . . . . . . . . . . . . . . . . . . . 11
3.2.2 Record Payload . . . . . . . . . . . . . . . . . . . . 12
3.2.3 Signature Payload. . . . . . . . . . . . . . . . . . . 13
3.3 SPP Messages . . . . . . . . . . . . . . . . . . . . . . . 14
3.3.1 Query Messages . . . . . . . . . . . . . . . . . . . . 14
3.3.2 Reply Messages . . . . . . . . . . . . . . . . . . . . 14
3.3.3 Policy Messages. . . . . . . . . . . . . . . . . . . . 15
3.3.4 Policy Acknowledgment Messages . . . . . . . . . . . . 15
3.3.5 Transfer Messages. . . . . . . . . . . . . . . . . . . 15
3.3.6 KeepAlive Messages . . . . . . . . . . . . . . . . . . 16
4. Policy Queries . . . . . . . . . . . . . . . . . . . . . . . . 16
4.1 Security Gateway Query . . . . . . . . . . . . . . . . . . 16
4.2 COMSEC Query . . . . . . . . . . . . . . . . . . . . . . . 17
4.3 Certificate Query. . . . . . . . . . . . . . . . . . . . . 18
5. Policy Records . . . . . . . . . . . . . . . . . . . . . . . . 19
5.1 Security Gateway Record. . . . . . . . . . . . . . . . . . 19
5.2 COMSEC Record. . . . . . . . . . . . . . . . . . . . . . . 21
5.3 Security Association Record. . . . . . . . . . . . . . . . 22
5.4 Policy Server Record . . . . . . . . . . . . . . . . . . . 23
5.5 Certificate Record . . . . . . . . . . . . . . . . . . . . 25
6. Transfer Records . . . . . . . . . . . . . . . . . . . . . . . 25
7. Policy Attribute Encoding. . . . . . . . . . . . . . . . . . . 26
8. SPP Message Processing . . . . . . . . . . . . . . . . . . . . 28
8.1 General Message Processing . . . . . . . . . . . . . . . . 28
8.2 Query Message Processing . . . . . . . . . . . . . . . . . 29
8.3 Reply Message Processing . . . . . . . . . . . . . . . . . 32
8.4 Policy Message Processing. . . . . . . . . . . . . . . . . 35
8.5 Policy Acknowledgment Message Processing . . . . . . . . . 37
8.6 Transfer Message Processing. . . . . . . . . . . . . . . . 38
8.7 KeepAlive Message Processing . . . . . . . . . . . . . . . 40
9. Policy Resolution . . . . . . . . . . . . . . . . . . . . . . . 41
9.1 Expansion of step 4. . . . . . . . . . . . . . . . . . . . 42
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10. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . 46
10.1 Message Type. . . . . . . . . . . . . . . . . . . . . . . 46
10.2 Message Code. . . . . . . . . . . . . . . . . . . . . . . 46
10.3 Identity Type . . . . . . . . . . . . . . . . . . . . . . 46
10.4 Payload Class . . . . . . . . . . . . . . . . . . . . . . 47
10.5 Query Type. . . . . . . . . . . . . . . . . . . . . . . . 47
10.6 Record Type . . . . . . . . . . . . . . . . . . . . . . . 47
10.7 Signature Type. . . . . . . . . . . . . . . . . . . . . . 47
10.8 Certificate Type. . . . . . . . . . . . . . . . . . . . . 47
10.9 Certificate Identity Type . . . . . . . . . . . . . . . . 47
10.10 Attribute Data Type. . . . . . . . . . . . . . . . . . . 48
10.11 User Name Type . . . . . . . . . . . . . . . . . . . . . 48
10.12 System Name Type . . . . . . . . . . . . . . . . . . . . 48
10.13 IPsec Action Attribute . . . . . . . . . . . . . . . . . 48
10.14 IKE Action Attribute . . . . . . . . . . . . . . . . . . 48
11. Security Considerations. . . . . . . . . . . . . . . . . . . . 49
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . 50
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Appendix A. DATA_TYPE Definitions. . . . . . . . . . . . . . . . . 51
Appendix B. An SPP Example . . . . . . . . . . . . . . . . . . . . 78
Appendix C. Decorrelation. . . . . . . . . . . . . . . . . . . . . 83
Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Author Information . . . . . . . . . . . . . . . . . . . . . . . . 92
1. Introduction
The IPsec protocols [Kent98] provide a mechanism for securing
communications at the IP layer and IKE [Harkins98] can be used to
provide keys for IPsec. Currently practice with these protocols
maintains an assumption that communicating hosts have some a-priori
knowledge of which communications with particular newtwork entities
must be secured. While this assumption is valid in some environments
(e.g. some VPN environments), it does not support more general IPsec
senarios in a scalable manner.
In order to allow IPsec to scale in general cases, it is necessary
to be able to identify which entities involved in a communication
will require IPsec to protect the communication and what their
policies are regarding it.
The Security Policy Protocol (SPP) defines how the policy information
is exchanged, processed, and protected by clients and servers. The
protocol also defines what policy information is exchanged and the
format used to encode the information. The protocol specifies six
different message types used to exchange policy information. An SPP
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message contains a message header section followed by zero or more SPP
payloads, depending on the message type.
SPP is part of the Security Policy System architecture [SPS]. This
document uses terms and references functionality described in [SPS].
The remainder of this section defines terms and concepts that will
be used throughout this document. Section 2 provides and overview
of the protocol. The remainder of the document describes the
encoding of the protocol and how SPP messages are processed.
1.1 Definitions
The following terms are used throughout this document, in addition to
the terms defined in [SPS] and defined for general policy terminology
[RGSC00].
Authoritative
Host A is authoritative over host B if host A has the right to
represent policy for host B. Host A may assert its relationship
to host B using policy server records (section 5.4), but MUST be
able to cryptographically prove the assertion.
Transitively Authoritative
A host is transitively authoritative over another host, A, if it
is either authoritative over host A or authoritative over a host,
B, which is trasitively athoritative over host A. For example,
if host X is authoritative for host Y and host Y is authoritative
for host Z, then host X is transitively authoritative for host Z.
Chain of Trust
A chain of trust is a set of cryptographically-proven authoritative
assertions that prove that a policy server is transitively
authoritative over the source or destination of a communication.
The chain of trust is used to prove that a policy server has
a right to be involved in an SPP exchange. See section 10 for
more about the chain of trust.
Keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT" and
"MAY" that appear in this document are to be interpreted as described
in [Bra97].
1.2 Policies
Defining and storing policies are beyond the scope if this document.
However, this section describes SPP's policy requirements and a
brief high-level look at its representation.
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Policy Representation
SPP provides both the comsec record (section 5.2) and the Security
Association (SA rec) record (section 5.3) to describe policies. The
comsec record defines the selectors that describe a communication
along with a permit or deny action. The SA rec defines the actions,
specifically the IPsec and IKE security associations, necessary for
the communication to proceed. A policy transferred by SPP, therefore,
MUST consist of one comsec record to describe the selectors of the
communication and zero or more SA recs which describe the security
associations that are required to complete the communication.
Decorrelation
Policies exchanged using SPP MUST be decorrelated as described in
Appendix C. Two policies are decorrelated if there exists at least
one selector in both policies for which their values do not intersect.
Decorrelation is necessary to permit policy servers to properly cache
policies.
2. Overview
This section provides an overview of the SPP operation. A more
detailed and complex example of SPP operation is available in appendix
B. This overview assumes the policy servers have been loaded with
policies for their security domains and the policy has been
appropriately decorrelated.
Security Security
Domain Foo Domain Foo
+----------+ +----------+
| Policy | | Policy |
| Server A | | Server B |
+----------+ +----------+
^ ^ ^ ^
+---------+ Q1 | | Q2 /\ /\ Q2 | | Q3 +----------+
| Host | R1 | | R2 / \ Q2/R2 / \ R2 | | R3 | Host |
| A |<--- -----><SGA ><------><SGB ><--- ---->| B |
+---------+ \ / \ / +----------+
\/ \/
Figure 1: Overview of SPP operation
Host A, wanting to communicate with Host B, invokes its policy client.
Host A's client sends a Query (Q1) to its configured local policy
server, Policy Server A. Policy Server A looks in its cache for a
policy record that matches the query. If it doesn't find one, it sends
a Query (Q2) containing the same policy request information to Host B.
Q2 is sent to Host B since Policy Server A may not know about the
existence of SGB or Policy Server B. This message includes a signature
that validates the authenticity and integrity of the query's content.
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(Q2) is intercepted by SGB. SGB forwards the message (Q2) to Policy
Server B. Policy server B verifies that it can accept queries from
Policy Server A and validates the signature in Q2. It searches its
database for the appropriate policy information after verifying that
it is authoritative over Policy Client B.
Policy Server B merges its local policy with the policy information in
(Q2) and it sends a Reply (R2) to Policy Server A. The reply includes
the original query information and all policy information needed to
allow Policy Client A to establish a secure communication with Host
B. Policy Server B also attaches additional information to the reply
asserting its authority over Host B.
When Policy Server A receives the reply (R2) from Policy Server A, it
validates the signature in R2 and cryptographically verifies that
Policy Server B is authoritative over Host B. It then merges is local
policy with the policy information in (R2) and sends a Reply (R1) to
Host A. Policy Server A caches the merged policy to use when
answering future queries. Host A may then use this information to
establish necessary security associations with Host B.
If, however, Policy Server B is not authoritative over Host B, it
would query Host B for its policy with respect to this particular
communication. Policy Server B would generate a third query (Q3). Host
B would respond with its policy in (R3). Policy Server B merges its
policy for this communication and the policy in (R3) before replying
to Policy Server A. Policy Server A processes the reply as it did
above.
SPP accommodates topology changes, hence policy changes, rather easily
without the scalability constraints imposed by static reconfiguration
of each client. The protocol is extensible and flexible It allows the
exchange of complex policy objects between clients and servers.
3. SPP Message
The SPP header is present in every message. It contains fields
identifying the message, the type of message, the status of the
message, the number of queries and/or record payloads, and the host
requesting policy information. The header also includes a timestamp
field that provides anti-replay protection. Following the header there
might be zero or more SPP payloads. Currently, there are three payload
types defined in SPP: Query, Record, and Signature payloads. See
section 3.2 for encoding details.
SPP has six distinct message types. Query messages contain a specific
request for policy information. Reply messages include policy records
that answer specific policy queries. Policy messages include policy
information and are utilized for up/downloading security policies to
and from a policy server. Policy Acknowledgment messages are utilized
to acknowledge corresponding Policy messages but do not themselves
contain policy information. Transfer messages, which include policy
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Internet Draft Security Policy Protocol January 2002
information, are utilized by policy servers to exchange bulk policy
information between servers. Finally, policy servers use keep alive
messages to inform security gateways and/or other monitoring devices
of the status of the server.
SPP messages MUST be authenticated either using IPsec [Kent98] or
another security mechanism. SPP provides a basic security mechanism
that can be used to provide authentication and integrity to its
messages when other security mechanisms are not in use. The SPP
authentication is especially useful when traversing heterogenous
domains and the identity of the policy server authoritative for the
destination is unknown. These services are provided using digital
signatures.
SPP caries signatures in the signature payload. The signature is
calculated over the entire SPP message. When this service is used, the
entity (host, policy server, or security gateway) verifying the
signature must have access to the public key that corresponds to the
private key used to sign the SPP message.
Certificate fetching is out of the scope of SPP. However, SPP
provides a simple certificate fetching mechanism for entities that
elect to use it as an alternative to other mechanisms. SPP suports
several Public Key certificates formats.
SPP is modular and extensible (see section 10 for IANA
considerations). New policy queries and records can be defined and
incorporated easily. This document defines a minimum set of queries
and policy records required in a policy-based security management
system.
3.1 SPP Message Format
An SPP message follows the format depicted in figure 2. It is
comprised of a header and zero or more SPP payloads. This section
defines the encoding for the SPP header. Sections 3.2 and 3.3 cover
the encoding for the SPP payload and message types, respectively.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -----
| VERSION | MTYPE | MCODE | RESERVED | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| MESSAGE ID | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| QCOUNT | RCOUNT | IDENTITY TYPE |R|D|C|I|T| RSVD| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | SPP
+ TIMESTAMP + Header
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | |
~ SENDER IDENTITY ~ |
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -----
| | SPP
~ SPP PAYLOADS... ~ Pay-
| | loads
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -----
Figure 2: Format of an SPP Message
The SPP header includes the following fields:
VERSION
A 1-octect field containing the version of the Security
Policy Protocol. This document describes version 1 of
the protocol.
MTYPE
A 1-octet field indicating the SPP message type.
The currently defined values are:
Message Type Value
Value Not Assigned 0
SPP-QUERY 1
SPP-REPLY 2
SPP-POL 3
SPP-POL_ACK 4
SPP-XFR 5
SPP-KEEP_ALIVE 6
values 7-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
MCODE
A 1-octet field providing information about this message.
All MTYPEs share a common MCODE space, although each message
type may not use all the defined message codes. See section
3.3 for the codes applicable to each message type.
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Action Code
Type Field
Value Not Assigned 0
message accepted 1
denied, administratively prohibited 2
denied, timestamp failed 3
denied, failed signature 4
denied, insufficient resources 5
denied, malformed message 6
denied, unspecified 7
partially available 8
unavailable 9
communication prohibited 10
partially available, server unreachable 11
values 12-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
RESERVED
A one octet field reserved for future use. Set value to all
zeros (0).
MESSAGE ID
A 4 octet field used to match messages and their responses
(e.g. queries to replies and policy to policy acknowledgement
messages). This value starts at "zero" and MUST be incremented
by (1) with every new message.
QCOUNT
A 1 octet field indicating the number of Query payloads
included in the message.
RCOUNT
A 1 octet field indicating the number of Record payloads
included in the message.
IDENTITY TYPE
This 1 octet field indicates the type of indentity found in
the Sender Identity field. Valid values are:
Identity Type Value
Value Not Assigned 0
IPV4_ADDR 1
IPV6_ADDR 2
Host DNS Name 3
values 4-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
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R
Raw policy flag. When this flag is set, policy servers
MUST NOT resolve the policies that they return.
D
Domain flag. Only resolve the policies as far as the last
policy server that is transitively authoritative over the
host requesting the policy resolution.
C
Dont cache flag. Don't cache the policies generated by the
query.
I
Ignore cache flag. Ignore any cached policies when processing
the query.
T
No chain-of-trust. A client indicates to its server that it
does not need chain-of-trust information. Policy Servers
MUST NOT set this flag. Only Policy Clients have the option
to set it.
RSVD
A 4 bit field reserved for future use.
Set value to all zeros (0).
TIMESTAMP
This 8-octet field contains a timestamp used to provide
limited protection against replay attacks. The timestamp
is formatted as specified by the Network Time Protocol
[RFC1305].
SENDER IDENTITY
A variable length field containing the identity of the sender
(host, security gateway, or policy server) of the SPP
message. The IDENTITY_TYPE field indicates the format of the
content in this field:
Identity Type Sender Identity
IPV4_ADDR An IPv4 Address
IPV6_ADDR An IPv6 Address
Host DNS Name A DNS name encoded as described
in [rfc1035]
This field does not allow IP address ranges or wildcards.
If this field is not aligned at the 4 octet boundary, the
field MUST be padded on the right with (00)hex to align on
the next 32-bit boundary.
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3.2 SPP Payloads
3.2.1 Query Payload
The Query payload contains fields to express a particular request for
policy information. Hosts, security gateways, or policy servers can
generate and transmit Query payloads in SPP messages to policy
servers. Figure 3 shows the format of the Query payload.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PCL | PID | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QUERY Data ...
+-+-+-+-+-+-+-+-
Figure 3: Format of Query Payload
The Query Payload fields are defined as follows:
PCL
A 1 octet field indicating the payload class. Query payloads
MUST contain (1) in the PCL field.
PID
A 1 octet field containing the ID number that identifies a
particular Query payload within an SPP message. Since one
SPP message can contain multiple Query payloads, each one
MUST be uniquely identified. This number MUST be unique
among the Query payloads within an SPP message.
RESERVED
A 2 octet field reserved for future use. Set value to all
zeros (0).
TYPE
A 2 octet field that specifies the type of query contained in
the QUERY Data fields. The currently defined queries are:
Query Payload Type Value
Value Not Assigned 0
Security Gateway Query 1
Communication Security Query 2
Certificate Query 3
values 4-65000 are reserved to IANA. Values 65001-65535 are for
private use among mutually consenting parties.
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LENGTH
A 2 octet field indicating the length in octets of the query
data field.
QUERY Data
A variable length field containing a single policy query. See
section 7 for encoding format.
3.2.2 Record Payload
The Record payload contains fields that assert policy information.
Hosts, security gateways, or policy servers can generate and transmit
Record payloads in SPP messages. Figure 4 shows the format of the
Record payload.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PCL | PID | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RECORD Data ...
+-+-+-+-+-+-+-+-
Figure 4: Format of Record Payload
The Record Payload fields are defined as follows:
PCL
A 1 octet field indicating the payload class. Record payloads
MUST contain (2) in the PCL field.
PID
This field is used to match queries to Record payloads. If
the record is a reply to a query, then the value for this
field MUST match the correspondent Query payload PID. If it
is not a reply to a query, the value SHOULD be set to zero.
RESERVED
A 2 octet field reserved for future use. Set value to all
zeros (0).
TYPE
A 2 octet field that specifies the type of Record. The
currently defined records are:
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Record Type Value
Value Not Assigned 0
Security Gateway Record 1
Communication Security Record 2
Security Association Record 3
Certificate Record 4
Policy Server Record 5
Transfer Record 6
values 7-65000 are reserved to IANA. Values 65001-65535 are for
private use among mutually consenting parties.
LENGTH
A 2 octet field indicating the length in octets of the RECORD
data field.
RECORD Data
A variable length field containing a single policy record. See
section 8 for encoding format.
3.2.3 Signature Payload
The Signature Payload contains data generated by the digital signature
function (selected by the originator), over the entire SPP message,
except for part of the Signature payload. This payload is used to
verify the integrity of the data in the SPP message. Figure 5 shows
the format of the Signature payload.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PCL | TYPE | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SIGNATURE Data ...
+-+-+-+-+-+-+-+-
Figure 5: Signature Payload Format
The Signature payload fields are defined as follows:
PCL
A 1 octet field indicating the payload class. Signature
payloads MUST contain (3) in the PCL field.
TYPE
A 1 octet field that specifies the signature algorithm
employed. The currently defined signature types are:
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Internet Draft Security Policy Protocol January 2002
Algorithm Type Value
Value Not Assigned 0
RSA 1
DSA 2
values 3-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
LENGTH
A 2 octet field indicating the length in octets of the
SIGNATURE Data field.
SIGNATURE Data
A variable length field that contains the results from
applying the digital signature function to the entire
SPP message (including the PCL, TYPE, and LENGTH fields
of the Signature payload), except for the Signature Data
field of the Signature payload.
3.3 SPP Messages
3.3.1 Query Message
An SPP-QUERY message is comprised of an SPP header, one or more Query
payloads, zero or more Record payloads, and a Signature payload, if
one is required. Query messages MUST always contain a Query
payload. Record payloads may optionally be included to pass policy
information along with the query. If the Signature payload is employed
it MUST be the last payload in the message. The Query message MTYPE
value is (1). The MCODE field must be set to zero (0).
3.3.2 Reply Message
An SPP-REPLY message is comprised of an SPP header, one or more Query
payloads, zero or more Record payloads which answer the corresponding
Query payload, and a Signature payload, if one is required. Reply
messages MUST contain a Query payload. Reply messages MUST include a
Record payload unless the reply contains an MCODE of values 2-8. If
the Signature payload is employed it MUST be the last payload in the
message. The MTYPE value for a Reply message is (2). The following
MCODE values may be used for Reply messages:
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Action Code
Type Field
Value Not Assigned 0
message accepted 1
denied, administratively prohibited 2
denied, timestamp failed 3
denied, failed signature 4
denied, insufficient resources 5
denied, malformed message 6
denied, unspecified 7
partially available 8
unavailable 9
communication prohibited 10
partially available, server unreachable 11
3.3.3 Policy Message
An SPP-POL message is comprised of an SPP header, one or more Record
payloads, and a Signature payload, if one is required. Policy messages
MUST NOT include Query payloads. If the Signature payload is employed
it MUST be the last payload in the message. The MTYPE value for a
Policy message is (3). The MCODE field must be set to zero (0).
3.3.4 Policy Acknowledgement Message
An SPP-POL_ACK message is comprised of an SPP header and a Signature
payload, if one is required. These messages MUST NOT contain Query or
Record payloads. The status of the associated Policy message is
expressed within the MCODE field. If the Signature payload is employed
it MUST be the only payload in the message. The MTYPE value for a
Policy Acknowledgement message is (4). The following MCODE values may
be used for Policy Acknowledgement messages:
Action Code
Type Field
Value Not Assigned 0
message accepted 1
denied, administratively prohibited 2
denied, timestamp failed 3
denied, failed signature 4
denied, insufficient resources 5
denied, malformed message 6
denied, unspecified 7
3.3.5 Transfer Message
An SPP-XFR message is comprised of an SPP header, one or more Record
payloads, and a Signature payload, if one is required. Transfer
messages MUST NOT include Query payloads. If the Signature payload is
employed it MUST be the last payload in the message. The MTYPE value
for a Transfer message is (5). The MCODE field must be set to zero
(0).
Sanchez, Condell [page 15]
Internet Draft Security Policy Protocol January 2002
3.3.6 KeepAlive Message
An SPP-KEEP_ALIVE message is comprised of an SPP header and a
Signature payload, if one is required. These messages MUST NOT contain
Query or Record payloads. If the Signature payload is employed it MUST
be the only payload in the message. The MTYPE value for a KeepAlive
message is (6). The MCODE field must be set to zero (0).
4. Policy Queries
4.1 Security Gateway Query
This basic query provides a dynamic mechanism to determine which
relevant security gateways, both primary and backup, are in the path
to a particular destination address. Since the answer to a request for
information could depend on the identity of the requestor, the host
address of the source of the intended communicaton is included in the
query. Figure 6 shows the format of the Security Gateway Query.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ SOURCE ADDRESS DATA ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ DESTINATION ADDRESS DATA ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Security Gateway Query Format
The Security Gateway Query fields are defined as follows:
SOURCE ADDRESS DATA
This variable length field contains a single IP address
(unicast) either in IPv4 or IPv6 format. The encoding
format is specified in section 7. The acceptable DATA_TYPE
values are 3 and 9.
DESTINATION ADDRESS DATA
This variable length field contains a single IP address
(unicast) either in IPv4 or IPv6 format. The encoding
format is specified in section 7. The acceptable DATA_TYPE
values are 6 and 12.
Sanchez, Condell [page 16]
Internet Draft Security Policy Protocol January 2002
4.2 COMSEC Query
The Communication Security Query (or COMSEC query) provides a dynamic
mechanism for a host or security gateway to inquire if a communication
having a particular set of characteristics is allowed. The
communication is described in terms of source and destination
addresses, protocols, source port, destination port, and other
parameters as defined in section 7. These parameters are known as
selectors in the IPsec context and are primarily the contents of the
IP, TCP, and UDP headers. Figure 7 shows the format of the COMSEC
Query.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ SOURCE ADDRESS DATA ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ DESTINATION ADDRESS DATA ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SELECTOR DATA ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: COMSEC Query Format
The COMSEC Query fields are defined as follows:
SOURCE ADDRESS DATA
This variable length field contains a single IP address
(unicast) either in IPv4 or IPv6 format. The encoding
format is specified in section 7. The acceptable DATA_TYPE
values are 3 and 9.
DESTINATION ADDRESS DATA
This variable length field contains a single IP address
(unicast) either in IPv4 or IPv6 format. The encoding
format is specified in section 7. The acceptable DATA_TYPE
values are 6 and 12.
SELECTOR DATA
This includes one or more fields following the encoding format
specified in section 7. The acceptable DATA_TYPE values are
15-29, inclusive.
Sanchez, Condell [page 17]
Internet Draft Security Policy Protocol January 2002
4.3 CERT Query
Mechanisms to dispatch and fetch public-key certificates are not part
of SPP. However, in the absence of external request/dispatch
mechanisms, SPP provides for a certificate request query that allows a
host, security gateway, or server to solicit a certificate. Figure 8
shows the format of the CERT Query.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CERT_TYPE | IDENTITY_TYPE | AUTHORITY_TYPE| RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ IDENTITY ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ CERTIFICATE AUTHORITY ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Certificate Query Format
The Certificate query fields are defined as follows:
CERT_TYPE
A 1 octet field that contains an encoding of the type of
certificate requested. Acceptable values are listed below:
Certificate Type Value
Value Not Assigned 0
PKCS #7 wrapped X.509 certificate 1
PGP Certificate 2
DNS Signed Key 3
X.509 Certificate - Signature 4
X.509 Certificate - Key Exchange 5
Kerberos Tokens 6
SPKI Certificate 7
values 8-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
IDENTITY_TYPE
This 1 octet field indicates the type of indentity found in
the Identity field. Valid values are listed below:
Sanchez, Condell [page 18]
Internet Draft Security Policy Protocol January 2002
Value Identity Type
0 Value Not Assigned
1 IPV4_ADDR
2 IPV6_ADDR
3 DNS Name
4 X.500 Distinguished Name
values 5-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
AUTHORITY_TYPE
This 1 octet field indicates the type of authority found in
the Certificate Authority field. Valid values are the same as
IDENTITY_TYPE.
IDENTITY
This variable length field contains the identity of the
principal by which the certificate should be located. The
value MUST be of the type stated in IDENTITY_TYPE.
CERTIFICATE AUTHORITY
A variable length field containing an encoding of an
acceptable certificate authority for the type of certificate
requested. The value MUST be of the type stated in
AUTHORITY_TYPE.
5. Policy Records
5.1 Security Gateway Record
This record contains information that indicates the IP addresses of
the interfaces for the the primary and secondary security gateways
protecting a host or group of hosts. The record contains the primary
and secondary gateways at one point in the communication path between
the source and destination addresses listed in the Security Gateway
query. If the IP datagram must traverse multiple gateways, a Security
Gateway Record must be included for each gateway. The list of
secondary security gateways is optional. Figure 9 shows the format of
the Security Gateway Record.
Sanchez, Condell [page 19]
Internet Draft Security Policy Protocol January 2002
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CACHE-EXPIRY |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FLAGS | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ PRIMARY SG ADDRESS ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SECONDARY SG ADDRESSES
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: Security Gateway Record Format
The Security Gateway Record fields are defined as follows:
CACHE-EXPIRY
A 4 octet field indicating the maximum amount of time,
in seconds, this policy record MAY be cached.
FLAGS
A 2 octet field indicating different options to aid in
interpreting the security gateway data. If not in use, set
value to all zeros (00)hex. Currently, no flag values are
defined so this field MUST be set to (00)hex.
RESERVED
A 2 octet field reserved for future use.
Set value to all zeros (0).
PRIMARY SG ADDRESS
A variable length field containing the IP address of the primary
security gateway for protecting a particular host. This
variable length field contains a single unicast IP
address. The encoding format is specified in section 7.
The acceptable DATA_TYPE values are 1 and 2.
SECONDARY SG ADDRESSES
This variable length field contains the IP addresses of one or
more secondary security gateways protecting a particular host.
This field may contain a list of single unicast IP addresses.
The encoding format is specified in section 7. The acceptable
DATA_TYPE values are 1 and 2.
Sanchez, Condell [page 20]
Internet Draft Security Policy Protocol January 2002
5.2 COMSEC Record
The COMSEC record indicates if a communication having a particular set
of characteristics is allowed or not. The communication is described
in terms of source and destination addresses, protocols, source ports,
destination ports, and other attributes defined in section 7. Figure
10 shows the format of the COMSEC Record.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CACHE-EXPIRY |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FLAGS | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ SOURCE ADDRESS DATA ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ DESTINATION ADDRESS DATA ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SELECTOR DATA ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: COMSEC Record Format
The COMSEC Record fields are defined as follows:
CACHE-EXPIRY
A 4 octet field indicating the maximum amount of time,
in seconds, this policy record MAY be cached.
FLAGS
A 2 octet field indicating different options to aid in
interpreting the selector data. If not in use, set
value to all zeros (0). Currently, no flag values are
defined so this field MUST be set to zero (0).
RESERVED
A 2 octet field reserved for future use.
Set value to all zeros (0).
Sanchez, Condell [page 21]
Internet Draft Security Policy Protocol January 2002
SOURCE ADDRESS DATA
This variable length field contains a single IP
address (unicast, anycast, broadcast (IPv4 only), or multicast
group), range of addresses (low and high values, inclusive),
address + mask, or a wildcard address. The encoding format is
specified in section 7. The acceptable DATA_TYPE values are
3-5 and 9-11, inclusive.
DESTINATION ADDRESS DATA
This variable length field contains a single IP
address (unicast, anycast, broadcast (IPv4 only), or multicast
group), range of addresses (low and high values, inclusive),
address + mask, or a wildcard address. The encoding format is
specified in section 7. The acceptable DATA_TYPE values are
6-8 and 12-14, inclusive.
SELECTOR DATA
This includes one or more fields following the encoding format
specified in section 7. The acceptable DATA_TYPE values are
15-29, inclusive.
5.3 Security Association Record
Security Association Records contain selectors and security
association attributes (appliers) that characterize a particular
Security Association between the source and destination addresses
listed in the record. This record contains data types as defined in
the section 7. Figure 11 shows the format of the SA Record.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CACHE-EXPIRY |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FLAGS | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ SOURCE ADDRESS DATA ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ DESTINATION ADDRESS DATA ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SELECTOR DATA AND APPLIERS...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: SA Record Format
The SA record fields are defined as follows:
Sanchez, Condell [page 22]
Internet Draft Security Policy Protocol January 2002
CACHE-EXPIRY
A 4 octet field indicating the maximum amount of time,
in seconds, this policy record MAY be cached.
FLAGS
A 2 octet field indicating different options to aid in
interpreting the selector data. If not in use, set
value to all zeros (0). Currently, no flag values are
defined so this field MUST be set to zero(0).
RESERVED
A 2 octet field reserved for future use.
Set value to all zeros (0).
SOURCE ADDRESS DATA
This variable length field contains a single IP
address (unicast, anycast, broadcast (IPv4 only), or multicast
group), range of addresses (low and high values, inclusive),
address + mask, or a wildcard address. The encoding format is
specified in section 7. The acceptable DATA_TYPE values are
3-5 and 9-11, inclusive.
DESTINATION ADDRESS DATA
This variable length field contains a single IP
address (unicast, anycast, broadcast (IPv4 only), or multicast
group), range of addresses (low and high values, inclusive),
address + mask, or a wildcard address. The encoding format is
specified in section 7. The acceptable DATA_TYPE values are
6-8 and 12-14, inclusive.
SELECTOR DATA AND APPLIERS
This includes one or more fields following the encoding format
specified in section 7. The acceptable DATA_TYPE values are
15-29 and 50-51, inclusive.
5.4 Policy Server Record
The Policy Server record indicates the host, security gateway, or
policy server for which a particular policy server is
authoritative. It represents an assertion, typically made by a policy
server, with repect to a member of a security domain that the server
represents. The record includes the Identity of the policy server and
the identity of a node (host, security gateway, another server, etc.).
Figure 12 shows the format of the Policy Server Record.
Sanchez, Condell [page 23]
Internet Draft Security Policy Protocol January 2002
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CACHE-EXPIRY |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FLAGS | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ POLICY SERVER IDENTITY ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ NODE IDENTITY ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Policy Server record format
The Policy Server Record fields are defined as follows:
CACHE-EXPIRY
A 4 octet field indicating the maximum amount of time,
in seconds, this policy record MAY be cached.
FLAGS
A 2 octet field indicating different options to aid in
interpreting the server and node data. If not in use, set
value to all zeros (0). Currently, no flag values are
defined so this field MUST be set to zero (0).
RESERVED
A 2 octet field reserved for future use.
Set value to all zeros (0).
POLICY SERVER IDENTITY
This variable length field contains the identity of the
policy server. It may contain an IP address (unicast)
either in IPv4 or IPv6 format. The encoding format is
specified in section 7. The acceptable DATA_TYPE values
are 1 and 2.
NODE IDENTITY
This variable length field contains the identity of a node
for which the policy server is authoritative. It may contain
an IP address (unicast) either in IPv4 or IPv6 format. The
encoding format is specified in section 7. The acceptable
DATA_TYPE values are 1 and 2.
Sanchez, Condell [page 24]
Internet Draft Security Policy Protocol January 2002
5.5 CERT Record
The CERT record contains one public key certificate. This record is
provided in SPP as an alternate mechanism for certificate
dispatching. Figure 13 shows the format of the CERT Record.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CACHE-EXPIRY |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CERT_TYPE | |
+-+-+-+-+-+-+-+-+ |
~ CERT_DATA ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: Certificate Record Format
CACHE-EXPIRY
A 4 octet field indicating the maximum amount of time,
in seconds, this policy record MAY be cached.
CERT_TYPE
This 1 octet field indicates the type of certificate or
certificate-related information contained in the Certificate
Data field. The values for this field are described in
Section 4.3.
CERT_DATA
This variable length field contains the actual encoding of
certificate data. The type of certificate is indicated by the
Certificate Type field.
6. Transfer Records
This record contains the text of the master file that is used to
configure the primary policy server.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ MASTER FILE TEXT ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: Security Gateway Record Format
The Transfer Record field is defined as follows:
Sanchez, Condell [page 25]
Internet Draft Security Policy Protocol January 2002
MASTER FILE TEXT
This variable length field contains the text of the master
file that is used to configure the policy server.
7. Policy Attribute Encoding
Query and Record payloads include several different selector types and
SA attributes with their associated values. These data are encoded
following a Type/Length/Value (TLV) format to provide flexibility for
representing different kinds of data within a payload. Certain
Data_Types with values of length equal to 2 octets follow the
Type/Value (T/V) format. The first bit of the DATA_TYPE field is used
to distinguished between the two formats. A value of (0) indicates a
TLV format while a value of (1) indicates TV format. This generic
encoding format is depicted in figure 15.
X = 0:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| DATA_TYPE | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DATA_VALUE...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
X = 1:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| DATA_TYPE | DATA_VALUE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: Generic Data Attribute Formats
The generic data attribute fields are defined as follows:
X
This bit indicates if the DATA_TYPE follows the TLV(0) or the
TV(1) format.
DATA_TYPE
A 2 octet field indicating the selector type. The currently
defined values are:
Sanchez, Condell [page 26]
Internet Draft Security Policy Protocol January 2002
DATA DATA_TYPE X
IPV4_ADDR 1 0
IPV6_ADDR 2 0
SRC_IPV4_ADDR 3 0
SRC_IPV4_ADDR_SUBNET 4 0
SRC_IPV4_ADDR_RANGE 5 0
DST_IPV4_ADDR 6 0
DST_IPV4_ADDR_SUBNET 7 0
DST_IPV4_ADDR_RANGE 8 0
SRC_IPV6_ADDR 9 0
SRC_IPV6_ADDR_SUBNET 10 0
SRC_IPV6_ADDR_RANGE 11 0
DST_IPV6_ADDR 12 0
DST_IPV6_ADDR_SUBNET 13 0
DST_IPV6_ADDR_RANGE 14 0
DIRECTION 15 1
USER_NAME 16 0
SYSTEM_NAME 17 0
XPORT_PROTOCOL 18 0
SRC_PORT 19 0
SRC_PORT_DYNAMIC 20 0
DST_PORT 21 0
DST_PORT_DYNAMIC 22 0
SEC_LABELS 23 0
V6CLASS 24 1
V6FLOW 25 0
V4TOS 26 1
ACTION 27 1
SRC_PORT_RANGE 28 0
DST_PORT_RANGE 29 0
IPSEC_ACTION 50 0
ISAKMP_ACTION 51 0
values 30-49 and 52-3200 are reserved to IANA. Values
3200-32767 are for private use among mutually consenting
parties.
LENGTH
A 2 octet field indicating the length of the selector value in
octets, not including any trailing padding added to the
DATA_VALUE field. The padding length is implicit.
DATA_VALUE
A variable length field containing the value of the selector
specified by DATA_TYPE. If the Selector value is not aligned at
the 4 octet boundary the field MUST be padded on the right with
(00)hex to align on the next 32-bit boundary.
Sanchez, Condell [page 27]
Internet Draft Security Policy Protocol January 2002
8. SPP Message Processing
SPP messages use UDP or TCP as their transport protocol. Messages
carried by UDP are restricted to 512 bytes (not counting the IP or UDP
headers). Fragmentation is allowed for messages containing more than
512 bytes. The SPP-XFR message SHOULD use TCP to transfer the contents
of the SPS Database from a primary to secondary policy server. A port
number has not yet been assigned for use with SPP. For now SPP
uses private UDP and TCP ports 55555.
8.1 General Message processing
For an SPP-Query or SPP-Pol message, the transmitting entity
MUST do the following:
1. Set a timer and initialize a retry counter.
2. If an SPP-Reply or SPP-Pol_Ack message corresponding to the
appropriate SPP-Query or SPP-Pol message is received within the
time interval, or before the retry counter reaches 0, the
transmitting entity continues normal operation.
3. If an SPP-Reply or SPP-Pol_Ack message corresponding to the
appropriate SPP-Query or SPP-Pol message is not received within
the time interval and a secondary policy server, which has not
been attempted on this value of the retry counter, is available,
the message is sent to the secondary server. If all the
secondary servers fail to respond within the time interval,
decrement the retry counter and resend the message to the
primary server.
4. If the retry counter reaches zero (0) the event MAY be logged
in the appropriate system audit file.
5. Following step 4, processing is more specific:
- For hosts and security gateways:
o the transmitting entity will clear state for this peer and
revert to using conventional security mechanisms.
- For policy servers:
o For SPP-Pol messages, clear state for this peer.
o For SPP-Query messages, clear state for this peer, lookup
policy in the server's SPS database and send an SPP-Reply
message per section 8.3 with the policy and MCODE 11.
Sanchez, Condell [page 28]
Internet Draft Security Policy Protocol January 2002
8.2 Query Message (SPP-Query) Processing
When creating a SPP-Query message, the entity (host, security gateway,
or policy server) MUST do the following:
1. Generate the Message ID value. This value starts at zero (0) and
MUST be incremented by (1) with every new message.
2. Set the value of the MTYPE field to 1
3. Set the MCODE value to zero (0).
4. Set the QCOUNT and RCOUNT fields. All fields MUST be
set to zero (0) when their corresponding payloads do no exist.
5. Set the flag bits accordingly and set the RESERVED field to
zero (0).
6. Set the IDENTITY_TYPE and IDENTITY of the Sender of the SPP
message.
7. Construct the SPP data payloads. A Query payload MUST be present
in this message.
8. Local policy information related to the query MAY be included as
Record payloads following the Query payloads.
9. A Policy Server record and a Cert Record SHOULD also be included
in the message. A Cert record MUST be included if the query is
a Cert Query to avoid a possible certificate query loop.
10. Calculate and place the timestamp value used for anti-replay
attack protection.
11. If the Signature payload is required for message integrity and
authentication, calculate a signature over the SPP header, SPP
payloads, the PCL, TYPE, and LENGTH fields of the Signature
payload. If required, the Signature payload MUST be the last
payload in the message.
When a policy server receives an SPP-Query message it MUST do the
following:
1. Check for SPP access control. If enabled, read the IP address in
the Sender's field of the SPP header.
- Verify whether or not the message is allowed. If the message
is not allowed then:
o send an SPP-Reply message with the MCODE 2 or 7
o discard message and the event MAY be logged.
- If the message is allowed, continue.
Sanchez, Condell [page 29]
Internet Draft Security Policy Protocol January 2002
2. Check timestamp field for anti-replay protection. If a replayed
message is detected:
- send an SPP-Reply message with the MCODE 3 or 7
- discard message and the event MAY be logged.
3. If the message requires signature validation.
- If a certificate record is present, the server MUST process
it, however, if the server already has a valid key for the
host or server identified in the certificate, the certificate
MAY be ignored.
- Fetch certificate or key corresponding to the IP address
found in the sender field of the SPP header.
- If a certificate or key is not available the entity MAY,
depending on configuration:
o choose to abort validation process, send SPP-Reply message
with MCODE 5 or 7, discard the message, and MAY log
the event.
o send an SPP-Query message to the source of the IP address
found in the sender field of the SPP header with a CERT
Query payload. Keep the SPP-Query message until the
SPP-Reply returns. Extract certificate or key, validate it
and proceed.
- Once a validated certificate or key is available then validate
signature.
o If validation fails, send SPP-Reply message with MCODE
5 or 7, discard the message, and the event MAY be logged.
4. Parse the Query records.
- If the SPP-Query message only contains cert queries:
o If the Identity field identifies the server or a member of
the server's security domain, send an SPP-Reply message per
section 8.3 with one or more cert records with the
certificates in the certification chain between the
requested Identity and Certificate_Authority and MCODE 1.
o Otherwise, send an SPP-Reply message per section 8.3 with
with MCODE 9 or 7.
Sanchez, Condell [page 30]
Internet Draft Security Policy Protocol January 2002
- If the SPP-Query message does not only contain cert queries:
o Check the Destination Address Data field to determine if
the message received was intended for a node that is a
member of the server's security domain.
o Continue processing.
5. If the message is for a node that is a member of the server's
security domain or the D bit in the SPP header is set and the
server is the outermost server that is authoritative over the
client or server that sent the message, then:
- Using src, dst, and any other applicable fields found in the
Query Payload, search the SPS database for an appropriate
policy.
o If a policy is found then construct an SPP-Reply message per
section 8.3 with appropriate payloads and MCODE 1.
o If a policy is not found then construct an SPP-Reply message
per section 8.3 with appropriate payloads and MCODE 9 or 7.
6. If the message is for a node that is not part of the server's
security domain then:
- If the I and R bits are not set in the SPP header, check the
Cache database for any relevant policies that apply to this
communication.
o If a policy is found then construct a SPP-Reply message per
section 8.3 with appropriate payloads and MCODE 1.
o If a policy is not found then continue.
- Check the Local database for any relevant policies that apply
to this communication.
- If the server is authoritative for the source address of
the query or a matching policy is found (A matching policy
is defined as a policy that either produces a comsec record
with an action attribute with the value "deny", or a policy
that would produce an SA record with one or more IPsec action
and IKE action attributes. A policy that only produces a
comsec record with an action attribute with the value "permit"
is not considered matching for this step.):
o Generate a new SPP-Query message. The new message MUST use
the same query payload as the old message. If the new
query will include policy from the server, then the policy
used SHOULD be the server's local policy merged with any
policies received with the query message. The Sender Address
will be the address of the server. The destination for this
message MUST be the one in the original SPP-Query received.
Sanchez, Condell [page 31]
Internet Draft Security Policy Protocol January 2002
o Keep state. Upon reception of the corresponding SPP-Reply
the policy server MUST send an SPP-Reply addressed to sender
of the original SPP-Query.
- If the server is not authoritative for the source address of
the query and a matching policy is not found then:
o The policy server MUST send the SPP-Query message unchanged.
The SPP-Query message MUST use the same source port that was
used to send it to the server so the next server that
processes the query will return it to the correct port.
This SPP-Query message MUST NOT be added to the retry queue
(section 8.1).
8.3 Reply Message (SPP-Reply) Processing
When creating a SPP-Reply message, the policy server MUST do the
following:
1. Copy the Message ID value from the corresponding SPP-Query
message into the Message ID field.
2. Set the value of the MTYPE field to 2
3. Set the MCODE value.
4. Set the QCOUNT and RCOUNT fields. All fields MUST be
set to zero (0) when their corresponding payloads do no exist.
5. Set the flag bits accordingly and set the RESERVED field to (0).
6. Set the IDENTITY_TYPE and IDENTITY of the Sender of the SPP
message.
7. Copy the Query payloads from the SPP-Query message to the
SPP-Reply message.
8. Construct the SPP data payload. Unless there is an error, at
least one record corresponding to each Query payload MUST be
present.
9. A policy server record and a CERT record MUST be added to the
SPP-Reply message if the the query to which this is a reply
did NOT have the T bit set. If the T bit is set, the records
SHOULD NOT be added.
10. Calculate and place the timestamp value used for anti-replay
attack protection.
11. If the Signature payload is required for message integrity and
authentication, calculate a signature over the SPP header, SPP
payloads, the PCL, TYPE, and LENGTH fields of the Signature
payload. If present, the Signature payload MUST be the last
payload in the message.
Sanchez, Condell [page 32]
Internet Draft Security Policy Protocol January 2002
12. The SPP-Reply message is sent to the host that is listed in
the Sender ID field of the SPP-Query to which this is a reply.
When a host or security gateway receives an SPP-Reply message it MUST
do the following:
1. Read the Message ID field. If the value does not match the value
of an outstanding SPP-Query message from a policy server then:
- silently discard the message and the event MAY be logged.
2. If Message ID matches, Check the timestamp field for anti-replay
protection. If a replayed message is detected the message is
silently discarded and the event MAY be logged.
3. Establish if the message requires signature validation by
searching for a Signature payload:
- if signature validation is required proceed with step 4.
- if signature validation is not required proceed with step 6.
4. Validate the signature on the message.
- If a certificate record is present, the server MUST process
it, however, if the server already has a valid key for the
host or server identified in the certificate, the certificate
MAY be ignored.
- Fetch certificate or key corresponding to the IP address
found in the sender field of the SPP header.
- If a certificate or key is not available the entity MAY:
o choose, depending on configuration, to abort validation
process, discard the message and MAY log the event.
o send an SPP-Query message to the source of the IP address
found in the sender field of the SPP header with a CERT
query payload. Keep SPP-Reply message until the
corresponding SPP-Reply returns. Extract certificate or
key, validate it and proceed.
5. Once a validated certificate or key is available then validate
signature.
If validation fails:
- the message is silently discarded and the event MAY be logged
If validation succeeds, continue processing.
6. For Policy Servers, validate the chain of trust.
A valid chain proves that policy has only been applied by
servers authorized to control policy over either the source or
destination host of the requested policy. The "chain"
represents the hierarchy of policy servers authoritative over
Sanchez, Condell [page 33]
Internet Draft Security Policy Protocol January 2002
the source of the communication and the heirarchy over the
destination. The chain may have a single "break" between the
two policy servers that represent the top of the two
heirarchies. It is formed by the information in the Policy
Server records and must be cryptographically proven that the
relationships described in those records are true.
- For each Policy Server record, verify that the Policy Server
is authoritative over the Node. This MUST be verified
cryptographically which MAY be accomplished using X.509
certificates [PKIXP1]. See section 11 for more details.
- Use the Policy Server records to Create a chain of hosts from
the destination host to this policy server where two records
are linked if the Node in one is the Policy Server in another.
- If the chain has no breaks, then this policy server MUST be
authoritative over the sender of the reply, otherwise drop
the message and stop processing it.
- If the chain has one break, then the last policy server on
the chain MUST be the sender of the reply, otherwise drop
the message and stop processing it.
- If the chain has two or more breaks, then there is an error
in the chain so drop the message and stop processing it.
- Verify that the Policy Server that is authoritative over the
destination host is authoritative over ALL destination hosts
in any comsec records.
7. If MCODE value is 2-7, 9 or 10:
For hosts or security gateways:
- clear all the state and stop processing
For policy servers:
- create an SPP-Reply message using the same MCODE value.
8. If the reply received correponds to a Cert query and the MCODE
is either (1) or (8) (accept or partially unavailable),
process message that was held up waiting for the cert.
9. For Policy Servers:
- Search the Local Policy Database for a policy entry that
matches the policy expressed in Query payload.
- If the R bit is not set, merge the local and non-local policy
information using the policy resolution proccess outlined in
section 9.
- If the R bit is set, include both the policies found in the
Local Policy Database and the policies in the reply to send
in the new reply.
Sanchez, Condell [page 34]
Internet Draft Security Policy Protocol January 2002
- If the merge fails send an SPP-Reply message with MCODE 10
or 7 and cache the failure.
- If the merge succeeds or the R bit is set:
o If the R and C bits are not set, cache policy information.
This includes all Record payloads.
o send an SPP-Reply message with the resulting policy records
and MCODE 1.
o If the R and D bits are not set and the merge indicated
that policies should be sent to one or more security
gateways, construct a signal for each gateway by creating
an SPP-Pol message with the appropriate policy from the
merge.
10. For hosts or security gateways:
- verify that the information in the Record payload corresponds
to the information in the Query payload.
- extract the records and create a policy entry in the SPD
according to local format. The policy is entered in the SPD
ONLY if local configuration allows.
8.4 Policy Message (SPP-Pol) Processing
When creating a SPP-Pol message, the entity (host, security gateway, or
policy server) MUST do the following:
1. Generate the Message ID value. This value starts at zero (0) and
MUST be incremented by (1) with every new message.
2. Set the value of the MTYPE field to 3.
3. Set the MCODE value to zero (0).
4. Set the RCOUNT field. The QCOUNT field MUST be set to zero (0)
since no query payloads exist.
5. Set the flag bits accordingly and set the RESERVED field to (0).
6. Set the IDENTITY_TYPE and IDENTITY of the Sender of the SPP
message.
7. Construct the SPP data payloads. A Record payload MUST be
present in this message. Query payloads MUST NOT be present.
8. Calculate and place the timestamp value used for anti-replay
attack protection.
9. If the Signature payload is required for message integrity and
authentication, calculate a signature over the SPP header, SPP
payloads, the PCL, TYPE, and LENGTH fields of the Signature
payload. If required, the Signature payload MUST be the
last payload in the message.
Sanchez, Condell [page 35]
Internet Draft Security Policy Protocol January 2002
When a policy server receives an SPP-Pol message it MUST do the
following:
1. Check for SPP access control. If enabled, read the IP address in
the Sender's field of the SPP header.
- Verify whether or not the message is allowed. If the message
is not allowed then:
o send an SPP-Pol_Ack message with the MCODE 2 or 7
o discard message and the event MAY be logged.
- If the message is allowed, continue.
2. Check timestamp field for anti-replay protection. If a replayed
message is detected:
- send an SPP-Pol_Ack message with the MCODE 3 or 7
- discard message and the event MAY be logged.
3. If the message requires signature validation:
- If a certificate record is present, the server MUST process
it, however, if the server already has a valid key for the
host or server identified in the certificate, the certificate
MAY be ignored.
- Fetch certificate or key corresponding to the IP address
found in the sender field of the SPP header.
- If a certificate or key is not available the entity MAY,
depending on configuration:
o choose to abort validation process, send SPP-Pol_Ack
message with MCODE 5 or 7, discard the message and MAY log
the event.
o send an SPP-Query message to the source of the IP address
found in the sender field of the SPP header with a CERT
Query payload. Keep SPP-Pol message until the SPP-Reply
returns. Extract certificate or key, validate it and
proceed.
- Once a validated certificate or key is available then
validate signature.
o If validation fails the message is silently discarded and
the event MAY be logged
4. If signature was not required or upon successful validation of a
signature parse the payloads.
Sanchez, Condell [page 36]
Internet Draft Security Policy Protocol January 2002
5. For hosts and security gateways:
- extract the records and create a policy entry in the cache
database. The policy MAY also be entered in the SPD, ONLY
if configuration allows.
6. For Policy Servers:
- extract the records, find corresponding policies in the
server's SPS database, merge the two sets of policies, and
create a policy entry in the cache database.
7. Send an SPP-Pol_Ack message with MCODE 1.
8.5 Policy Acknowledgement Message (SPP-Pol_Ack) Processing
When creating a SPP-Pol_Ack message, the policy server MUST do the
following:
1. Copy the Message ID value from the corresponding SPP-Pol message
into the Message ID field.
2. Set the value of the MTYPE field to 4
3. Set the MCODE value.
4. Set the QCOUNT and RCOUNT fields. All fields MUST be
set to zero (0).
5. Set the flag bits accordingly and set the RESERVED field to (0).
6. Set the IDENTITY_TYPE and IDENTITY of the Sender of the SPP
message.
7. Query or Record payloads MUST NOT be present.
8. Calculate and place the timestamp value used for anti-replay
attack protection.
9. If the Signature payload is required for message integrity and
authentication, calculate a signature over the SPP header, the
PCL, TYPE, and LENGTH fields of the Signature payload.
When a host, security gateway, or policy server receives an
SPP-Pol_Ack message the entity MUST do the following:
1. Read the Message ID field. If the value does not match the value
of an outstanding SPP-Pol message from a policy server then:
- silently discard the message and the event MAY be logged.
2. If Message ID matches then check the timestamp field for
anti-replay protection. If a replayed message is detected the
message is silently discarded and the event MAY be logged.
Sanchez, Condell [page 37]
Internet Draft Security Policy Protocol January 2002
3. If the message is original (not replayed) and the message
requires signature validation then:
- If a certificate record is present, the server MUST process
it, however, if the server already has a valid key for the
host or server identified in the certificate, the certificate
MAY be ignored.
- Fetch certificate or key corresponding to the IP address
found in the sender field of the SPP header.
- If a certificate or key is not available the entity MAY:
o choose, depending on configuration, to abort validation
process, discard the message and MAY log the event.
o send an SPP-Query message to the source of the IP address
found in the sender field of the SPP header with a CERT
Query payload. Keep SPP-Pol_ack message until the SPP-Reply
returns. Extract certificate or key, validate it and
proceed.
4. Once a validated certificate or key is available then validate
the signature.
If validation fails:
- the message is silently discarded and the event MAY be logged
If validation succeeds:
- read the MCODE field and proceed accordingly. If no errors,
clear all the state for this message and proceed.
8.6 Transfer Message (SPP-XFER) Processing
When creating an SPP-Xfer message, the policy server MUST do the
following:
1. Generate the Message ID value. This value starts at zero (0) and
MUST be incremented by (1) with every new message.
2. Set the value of the MTYPE field to 5.
3. Set the MCODE value to (0).
4. Set the RCOUNT field. The QCOUNT field MUST be set to zero (0)
since no query payloads exist.
5. Set the flag bits accordingly and set the RESERVED field to
zero (0).
6. Set the IDENTITY_TYPE and IDENTITY of the Sender of the SPP
message.
7. Construct the SPP data payloads. A single Transfer Record MUST
be present in this payload and MUST contain the master file
used to configure this policy server.
Sanchez, Condell [page 38]
Internet Draft Security Policy Protocol January 2002
8. Calculate and place the timestamp value used for anti-replay
attack protection.
9. If the Signature payload is required for message integrity and
authentication, calculate a signature over the SPP header, SPP
payloads, the PCL, TYPE, and LENGTH fields of the Signature
payload. If required, the Signature payload MUST be the last
payload in the message.
When a security gateway receives an SPP-Xfer message it MUST do the
following:
1. Check for SPP access control. If enabled, read the IP address in
the Sender's field of the SPP header.
- Verify whether or not the message is allowed. If the message
is not allowed then:
o discard message and the event MAY be logged.
- If the message is allowed, continue.
2. Check timestamp field for anti-replay protection. If a replayed
message is detected:
- discard message and the event MAY be logged.
3. If the message requires signature validation:
- If a certificate record is present, the server MUST process
it, however, if the server already has a valid key for the
host or server identified in the certificate, the certificate
MAY be ignored.
- Fetch certificate or key corresponding to the IP address
found in the sender field of the SPP header.
- If a certificate or key is not available the entity MAY,
depending on configuration:
o choose to discard the message, and MAY log the event.
o send an SPP-Query message to the source of the IP address
found in the sender field of the SPP header with a CERT
Query payload. Keep the SPP-Query message until the
SPP-Reply returns. Extract certificate or key, validate it
and proceed.
- Once a validated certificate or key is available then
validate signature.
o discard the message, and the event MAY be logged.
Sanchez, Condell [page 39]
Internet Draft Security Policy Protocol January 2002
4. If signature was not required or upon successful validation of a
signature parse the payload.
- extract the Transfer Record and save the master file that it
contains.
- Flush the contents of the SPS database, domain database, and
cache.
- Load the new information from the transferred master file into
the databases.
8.7 KeepAlive Message (SPP-KEEP_ALIVE) Processing
When creating an SPP-Keep_Alive message, the policy server MUST do the
following:
1. Generate the Message ID value. This value starts at zero (0) and
MUST be incremented by (1) with every new message.
2. Set the value of the MTYPE field to 6.
3. Set the MCODE value to zero (0).
4. Set the QCOUNT and RCOUNT fields. All fields MUST be
set to zero (0).
5. Set the flag bits accordingly and set the RESERVED field to (0).
6. Set the IDENTITY_TYPE and IDENTITY of the Sender of the SPP
message.
7. Query or Record payloads MUST NOT be present.
8. Calculate and place the timestamp value used for anti-replay
attack protection.
9. If the Signature payload is required for message integrity and
authentication, calculate a signature over the SPP header, the
PCL, TYPE, and LENGTH fields of the Signature payload.
When a host or security gateway receives an SPP-Keep_Alive message it
MUST do the following:
1. Check for SPP access control. If enabled, read the IP address in
the Sender's field of the SPP header.
- Verify whether or not the message is allowed. If the message
is not allowed then discard message and the event MAY be
logged.
2. Check timestamp field for anti-replay protection. If a replayed
message is detected discard message and the event MAY be logged.
Sanchez, Condell [page 40]
Internet Draft Security Policy Protocol January 2002
3. If the message requires signature validation then:
- If a certificate record is present, the server MUST process
it, however, if the server already has a valid key for the
host or server identified in the certificate, the certificate
MAY be ignored.
- Fetch certificate or key corresponding to the IP address
found in the sender field of the SPP header.
- If a certificate or key is not available the entity MAY
depending on configuration:
o choose to abort validation process, discard the message and
the event MAY be logged.
o send an SPP-Query message to the source of the IP address
found in the sender field of the SPP header with a CERT
Query payload. Keep SPP-Keep_Alive message until the
SPP-Reply returns. Extract certificate or key, validate it
and proceed.
- Once a validated certificate or key is available then
validate signature.
o If validation fails the message is silently discarded and
the event MAY be logged
4. If signature validation was not required or upon successful
validation of a signature, the event MAY be logged.
9. Policy Resolution
When a policy server receives a reply, it must merge its local
policy for the communication with any non-local policies contained in
the reply. The merging process creates a new policy that is the
intersection of the local and remote policies. It then uses the
merged policy as its reply to the query and caches it. The policy
resolution process is as follows.
A message (set of policies) consists of one comsec record and zero or
more SA recs that apply to the communication in the comsec record.
1. Get local and remote policies for the requested communication.
2. Verify that the remote policy answer the query. This may be
accomplished by intersecting the query with the comsec record
int the answer and verify that they have a non-nil intersection.
3. Merge the local and remote comsec records. If they don't merge
return error. If they do put merged comsec record in answer.
Sanchez, Condell [page 41]
Internet Draft Security Policy Protocol January 2002
4. Merge the two sets of policies (SA recs). The merge must:
- Find the intersection of the policies between matching endpoints.
o If the intersection is nil, then the policies do not permit
the communication and an error should be returned. It is not
necessary to continue processing other endpoints.
o If the intersection is not nil, then the intersection should
be added to the reply policy.
- Take into account ipsec action locations when determining the
endpoints to intersect.
- preserve the ordering of the policies so that the SA recs are
generated in the correct order.
5. The policy created by the intersections is the policy that should
be cached and used as a reply to the query.
Step 4 requires that the policy server must be able to determine all
the sets of endpoints described by the policy. The endpoint
information comes from two places: the source and destination
addresses in the query (which is possibly more specific than those
fields in the policies) and the location information in the
ipsec_action attribute. Section 9.1 describes a method of processing
this step in more detail.
The location information may offer the policy server some
flexibility in how it interprets endpoints for the communication. For
example, if the policy indicates a tunnel must be established with any
host or gateway in the source or destination host's domain, the policy
server can choose the endpoint within the bounds of the policy. This
choice can be made randomly, using a set policy (e.g., always choose
the outermost gateway permitted by the policy), or using additional
information the server may maintain for this purpose. For example,
the server may keep track of previous policy decisions it made and use
those as hints to which security associations may already exist. It
can then try to make decisions that will allow these security
associations to be reused.
9.1 Expansion of step 4
This section describes a method of merging two sets of policies. It
describes which policies should be merged together and how to maintain
the appropriate order of the policies. It does not describe the
merging of individual policies which involves taking the intersecting
the selectors and appliers. Other methods to implement the merge may
be used.
Start with two sets of ordered policies. One set is the remote set
of policies that has been received through an SPP exchange. The other
is a local set of policies that was found in a local policy database.
Sanchez, Condell [page 42]
Internet Draft Security Policy Protocol January 2002
1) Attempt to merge any records that may be merged and interleave
messages to preserve ordering:
for each SA rec in remote message:
Check remote src, dst, location src, and location dst
endpoints against SA recs in local message, in order. Check
against the following rules which are grouped into three
priorities. The high priority is for those policies that
match and should be merged. The low priority is for those
policies that don't merge, but care must be taken to insure
that they are ordered correctly. The final group is policies
that do not match in any way.
Attempt to match each of the unprocessed local SA recs to the
remote SA rec. Find the SA rec (or SA recs, there might be more
than one applicable match) to find the highest priority match.
If the highest priority match is a low priority match, compare
it to the remaining remote SA recs. If there is a remote SA
rec to which it has a high priority match, take the local SA
rec and goto step 3.
Otherwise, process the romote SA rec against each of the highest
matching local SA recs as specified by their priority.
High Priority Matches:
o if both the remote src and dst match the local src and dst
and either
the remote location src and dst and the local location
src and dst match
or
the local or remote location src and dst are set to
zero and the other location src and dst match the src
and dst
- take each unprocessed SA rec in the local message
before this matching one and goto 3.
- merge the two SA recs and goto 3.
o if (remote src and dst match the local location src and dst
and the remote location src and dst either match the remote
src and dst or are zero) or (local src and dst match the
remote location src and dst and the local location src and
dst either match the local src and dst or are zero), then:
- take each unprocessed SA rec in the local message
before this one and goto 3.
Sanchez, Condell [page 43]
Internet Draft Security Policy Protocol January 2002
- Take the SA rec with the location endpoints that matched
the other src and dst and send it to step 3, but return
the results here for further processing.
- merge the other SA rec with the SA rec resulting from
3 that has the same src and dst. Take this merged SA
rec and goto 3. If the sa rec that was sent to step
3 above was the local sa rec, send the remaining SA
recs that resulted from 3 to step 3, otherwise send
them to step 2.
Low Priority Matches:
o If both the remote src and dst match the local src and dst
but the remote location src and dst and the local location
src and dst do not match, then they do not merge.
- take each unprocessed SA rec in the local message
before this one and goto 3.
- On a query, order the local SA rec before the remote SA
rec. On a reply, order the remote SA rec before the local
SA rec. Maintaining query/reply order, take the local
SA rec to step 3 and the remote SA rec to step 2.
o if the remote src and local src match, but the dsts do not,
or the remote dst and local dst match and the srcs do not,
then:
- take each unprocessed SA rec in the local message
before this one and goto 3.
- On a query, order the local SA rec before the remote SA
rec. On a reply, order the remote SA rec before the local
SA rec. Maintaining query/reply order, take the local
SA rec to step 3 and the remote SA rec to step 2.
No Matches:
o if no endpoints match, then goto 2.
If there are any SA recs remaining in the local message, take each
of them to step 3.
2) Verify local policies for non end-to-end SA recs. This involves
finding policies that are being merged which involve intermediate
enforcement points and check the local policy for the intermediate
points.
The SA rec is directly from the remote message so the
communication must be verified:
Sanchez, Condell [page 44]
Internet Draft Security Policy Protocol January 2002
A) Check the src and dst and the location src and dst.
If a pair is the same as the communication endpoints,
zero, or is ambiguous, do not continue processing it.
Continue processing any that do not fit these conditions.
If neither pair continues processing, goto 3.
o look in the local database for a policy that matches
the communication described by these endpoints.
o check the comsec record to verify that it is
permitted. (If not deny entire communication).
o For each SA rec from the local policy, except a matching
SA rec, goto 3.
o If there is a matching SA rec, merge it with the remote
SA rec and goto 3. Else take the remote SA rec and
goto 3.
3) Process location fields to resolve any ambiguities that they may
describe and define any new SAs that the location fields may
specify.
If the loc fields are empty, then goto 4.
- If the location fields and local decision making over any
ambiguities indicate that a host or GW controlled by this PS
should be a LOC DST, then replace the LOC DST with the gateway's
ipaddress or DNS name.
- If the location fields and local decision making over any
ambiguities indicate that a host or GW controlled by this PS
should be a LOC SRC, then replace the LOC SRC with the gateway's
ipaddress or DNS name.
- If both the location src and location dst fields are specific
hosts or gateways (i.e. not ambiguous) and not the same as the
src and dst fields, create a new SA rec to reflect the policy
between the location src and dst.
o create the new SA rec.
- Take the original SA rec and any that have been added by this
process and goto 4.
4) Create a reply message and signals to enforcement points as needed.
If this is a query:
Add the SA rec to the answer.
Sanchez, Condell [page 45]
Internet Draft Security Policy Protocol January 2002
If this is a reply:
If SA rec dst is for GW controlled by this PS:
- If no signal message exists for this GW, yet, create one
with a comsec record formed from the information in the
previous SA rec (in the order that has been established).
- Add the SA rec to the signal for this GW.
- Add SA rec to answer.
If SA rec src is for GW controlled by this PS:
- If no signal message exists for this GW, yet, create one
with a comsec record formed from the information in the
previous SA rec (in the order that has been established).
- Add the SA rec to the signal for this GW.
If neither endpoint is for GW controlled by this PS:
- Add SA rec to answer.
10. IANA Considerations
This document contains many "magic numbers" to be maintained by the
IANA. This section explains the criteria to be used by the IANA to
assign numbers beyond the ones defined in this document.
10.1 Message Type
The MTYPE field of the SPP Header (section 3.1) defines message
exchange types for SPP. Requests for assignment of new message type
values 7-250 must be accompanied by a reference to a standards-track
or Informational RFC which describes the new message type and how it
should be processed. Values 251-255 are for private use.
10.2 Message Code
The MCODE field of the SPP Header (section 3.1) defines the acceptable
return codes for an SPP message. Requests for assignment of new
message code values 12-250 must be accompanied by a description of the
conditions under which the code is returned. Values 251-255 are for
private use.
10.3 Identity Type
The Identity Type field of the SPP Header (section 3.1) defines the
acceptable formats for identifying the sender of an SPP message.
Requests for assignment of new identity types 4-250 must be
accompanied by a description of the format of the corresponding SENDER
IDENTITY field in the header. Values 251-255 are for private use.
Sanchez, Condell [page 46]
Internet Draft Security Policy Protocol January 2002
10.4 Payload Class
The first octect of each payload header (section 3.2) defines the type
of payload that follows it. Requests for assignment of new message
type values 4-250 must be accompanied by a reference to a
standards-track or Informational RFC which describes the format of the
payload's header and data. Values 251-255 are for private use.
10.5 Query Type
The query type (section 3.2.1) defines how the payload data will be
interpreted and answered. Requests for assignment of new query type
values 4-65000 must be accompanied by a reference to a standards-track
or Informational RFC which describes the format of the data and how it
should be used. Values 65001-65535 are for private use.
10.6 Record Type
The record type (section 3.2.2) defines how the payload data will be
interpreted. Requests for assignment of new record type values
4-65000 must be accompanied by a reference to a standards-track or
Informational RFC which describes the format of the data and how it
should be used. Values 65001-65535 are for private use.
10.7 Signature Type
The signature type (section 3.2.3) defines the signature algorithm
used to sign the SPP message. Requests for assignment of new
signature type values 3-250 must be accompanied by a reference to a
standards-track or Informational RFC or a reference to published
cryptographic literature which describes this algorithm. Values
251-255 are for private use.
10.8 Certificate Type
The Cert Type field of the Certificate query and record (section 3.1)
defines the type of certificate requested or included in the payload.
Requests for assignment of new certificate types 8-250 must be
accompanied by a description of certificate and its encoding. Values
251-255 are for private use.
10.9 Certificate Identity Type
The Identity Type and Authority Type fields of the certificate query
(section 4.3) define the acceptable formats for identifying the host
and its certificate authority for which a certificate is requested.
Requests for assignment of new certificate identity types 5-250 must
be accompanied by a description of the format of the corresponding
IDENTITY and CERTIFICATE AUTHORITY fields in the payload. Values
251-255 are for private use.
Sanchez, Condell [page 47]
Internet Draft Security Policy Protocol January 2002
10.10 Attribute Data Type
The Data_Type field of the attribute encoding (section 7) defines the
type of attribute included in the data_value field. Requests for
assignment of new attribute data types 30-49 and 52-3200 must be
accompanied by a description of the X bit indicating if it is in TLV
or TV format, a detailed description of the Data_Value field
corresponding to the attribute type, and in which record and query
data fields the type may be used. Values 3200-32767 are for private
use.
10.11 User Name Type
The Name_Type field of the user name attribute (section A.16) defines
the data in the Name field of the attribute. Requests for assignment
of new user name types 2-250 must be accompanied by a description of
the corresponding Name field. Values 251-255 are for private use.
10.12 System Name Type
The Name_Type field of the system name attribute (section A.17)
defines the data in the Name field of the attribute. Requests for
assignment of new system name types 9-249 must be accompanied by a
description of the corresponding Name field. Values 251-255 are for
private use.
10.13 IPsec Action Attribute
The assigned values of Lifetime_Type, Cipher_Alg, Int_Alg_Esp,
Int_Alg_Ah, and Ipcomp_Alg use the values of their associated fields
in [Piper98] and are updated when the IANA updates their values in
[Piper98].
The Loc_Type field of the IPsec action attribute (section A.30)
defines the type of location address in the Loc_Src and Loc_Dst
fields. Requests for assignment of new location types 5-250 must be
accompanied by a description of the corresponding Loc_Src and Loc_Dst
field. Values 251-255 are for private use.
The Loc_Src and Loc_Dst fields of the IPsec action attribute (section
A.30) may define a general location type. Requests for assignment of
new general location values 5-250 must be accompanied by a description
of the general location type. Values 251-255 are for private use.
10.14 IKE Action Attribute
The assigned values of Group Description, Group_Type, Auth_Method,
PRF, Lifetime_Type, Cipher_Alg, and Hash_Alg use the values of their
associated fields in [Harkins98] and are updated when the IANA updates
their values in [Harkins98].
Sanchez, Condell [page 48]
Internet Draft Security Policy Protocol January 2002
The Mode field of the IKE action attribute (section A.31) defines the
IKE Mode. Requests for assignment of new Modes 3-250 must only be
done when new modes are added to the IKE protocol. Values 251-255 are
for private use.
11. Security Considerations
All SPP messages MUST be authenticated to prove which policy server
sent the message and that it hasn't been modified en-route. The
authentication MAY be provided using the signature payload provided
by SPP or some other mechanism such as IPsec.
However, since the policy data may change during SPP exchanges, the
messages cannot maintain a signature from every policy server that is
involved in the policy exchange. SPP depends on a chain-of-trust for
end-to-end authentication. Messages between policy servers are
authenticated and contain policy server records, which claim
authorization over a node, and certificates, which include signed
proof that the server is authoritative the node. The receiving server
can use this information to create a chain of servers involved in the
policy exchange from itself to the server authoritative over the
destination of the query. This chain of authorized servers is used to
prove that only servers that have authorization to be involved in the
communication were involved. Section 8.3 for details on how the chain
is created and verified.
Policy information may be considered sensitive, since examining
policies may expose expoitable weaknesses in the policies. The
distribution of policies may be limited to reduce this risk. Policy
distribution MAY be limited to those nodes that need to know the
information. Limiting distribution any further negates the purpose of
the protocol so is not allowed for proper use of SPP.
Additional protections, such as privacy protection, may be desired
by some domains. This can be achieved by encrypting SPP data.
Encrypting SPP messages is out of scope of this document and may
be discussed elsewhere.
SPP uses timestamps to protect against replay attacks. This requires
that nodes have adequately synchronized time-of-day clocks. It is
necessary to choose an appropriately sized window of time in which
timestamps may be accepted. If the window is too small, valid
messages may be discarded. On the other hand, if the window is too
large it may leave the server open to replay attacks.
Sanchez, Condell [page 49]
Internet Draft Security Policy Protocol January 2002
Acknowledgments
The authors thank Charles Lynn, Steve Kent and John Zao for their
participation in requirements discussions for the Security Policy
System. Our gratitude to Charlie Lynn, Matt Fredette, Alden Jackson,
Dave Mankins, Marla Shepard and Pam Helinek for the contributions to
this document. We thank Joel Levin and Mary Hendrix (INS Corp.) for
reviewing this document. We thank Isidro Castineyra for his
contributions to the early parts of this work.
References
[Bra97] Bradner, S., "Key Words for use in RFCs to indicate
Requirement Levels", RFC2119, March 1997.
[Kent98] S. Kent, R. Atkinson, "Security Architecture for the
Internet Protocol", RFC 2401, November 1998.
[KA98b] S. Kent, R. Atkinson, "IP Encapsulating Security
Payload (ESP)", RFC 2406, November 1998.
[isakmp] D. Maughan, M. Schertler, M. Schneider, J. Turner, "Internet
Security Association and Key Management Protocol (ISAKMP)",
RFC 2408, November 1998.
[RFC1035] Mockapetris, P., "Domain Names - Implementation and
Specification", RFC 1035, November 1987.
[RFC1305] Mills, D., "Network Time Protocol (Version 3):
Specification, Implementation and Analysis", RFC 1305, March
1992.
[RGSC00] F. Reichmeyer , D. Grossman, J. Strassner, M. Condell,
"A Common Terminology for Policy Management" Internet Draft
draft-reichmeyer-polterm-terminology-00.txt, March 2000.
[PKIXP1] R. Housley, W. Ford, W. Polk, D. Solo, "Internet Public
Key Infrastructure: X.509 Certificate and CRL Profile".
RFC 2459, January 1999.
[Harkins98] D. Harkins, D. Carrel, "The Internet Key Exchange (IKE)",
RFC 2409, November 1998.
[Piper98] D. Piper, "The Internet IP Security Domain of
Interpretation for ISAKMP", RFC 2407, November 1998.
[SPS] M. Richardson, A. Keromytis, L. Sanchez, "IPsec Policy
Discovery Protocol Requirements", Internet Draft,
draft-richardson-ipsp-requirements-00.txt, October 1999.
[SPSL] M. Condell, C. Lynn, J. Zao "Security Policy Specification
Language", Internet Draft draft-ietf-ipsp-spsl-00.txt,
March 2000
Sanchez, Condell [page 50]
Internet Draft Security Policy Protocol January 2002
APPENDIX A
DATA_TYPE Definitions
The encoding of each selector and SA attribute is decribed here.
Each attribute is described using the following set of data:
X The value of the X bit in the attribute encoding.
DATA_TYPE The value of the DATA_TYPE field in the attribute
encoding.
LENGTH The length of the data to use if X = 0.
list 'yes' indicates the attribute may be used as a list
as described below.
DATA_VALUE Encoding of the DATA_VALUE field in the attribute
encoding.
Attributes generally encode "any" in one of two ways. If using
the TLV format (X = 0) then the length is set to 0 to indicate any.
If the TV format (X = 1) is used, then the value is set to 0;
Attributes that may be expressed as lists provide the DATA_VALUE
encoding for one element of the list. Multiple list elements may be
expressed by concatenating multiple list elements. The LENGTH of
attribute is the number of elements present times the length of one
list element. Therefore, when reading an attribute that can be
expressed as a list, the number of list elements may be determined by
dividing the length by the size of a single list element.
The remainder of this appendix describes the values and encoding for
each selector and SA attribute specified in section 7.
A.1 IPV4_ADDR
X 0
DATA_TYPE 1
LENGTH 4 if an IP address is present,
0 if no IP address is present.
list No
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ADDRESS
An IPV4 address
Sanchez, Condell [page 51]
Internet Draft Security Policy Protocol January 2002
A.2 IPV6_ADDR
X 0
DATA_TYPE 2
LENGTH 16 if an IP address is present,
0 if no IP address is present.
list No
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| ADDRESS |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ADDRESS
An IPV6 address
A.3 SRC_IPV4_ADDR
X 0
DATA_TYPE 3
LENGTH 4 times the number of addresses in the list.
A length of 0 indicates any address.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRC ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SRC ADDRESS
An IPV4 address representing the source host of a
communication
A.4 SRC_IPV4_ADDR_SUBNET
X 0
DATA_TYPE 4
LENGTH 8 times the number of subnets in the list.
A length of 0 indicates any subnet.
list Yes
DATA_VALUE
Sanchez, Condell [page 52]
Internet Draft Security Policy Protocol January 2002
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUBNET ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUBNET MASK |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SUBNET ADDRESS
An IPV4 address representing the source subnet of a
communication
SUBNET MASK
An IPV4 address representing the source subnet mask of a
communication
A.5 SRC_IPV4_ADDR_RANGE
X 0
DATA_TYPE 5
LENGTH 8 times the number of address ranges in the list.
A length of 0 indicates any address.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LOWER BOUND SRC ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UPPER BOUND SRC ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
LOWER BOUND SRC ADDRESS
An IPV4 address representing the includsive lower-bound
of a range of source addresses of a communication.
UPPER BOUND SRC ADDRESS
An IPV4 address representing the includsive upper-bound
of a range of source addresses of a communication.
A.6 DST_IPV4_ADDR
X 0
DATA_TYPE 6
LENGTH 4 times the number of addresses in the list.
A length of 0 indicates any address.
list Yes
DATA_VALUE
Sanchez, Condell [page 53]
Internet Draft Security Policy Protocol January 2002
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DST ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DST ADDRESS
An IPV4 address representing the destination host of a
communication
A.7 DST_IPV4_ADDR_SUBNET
X 0
DATA_TYPE 7
LENGTH 8 times the number of subnets in the list.
A length of 0 indicates any subnet.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUBNET ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUBNET MASK |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SUBNET ADDRESS
An IPV4 address representing the destination subnet of a
communication
SUBNET MASK
An IPV4 address representing the destination subnet mask
of a communication
A.8 DST_IPV4_ADDR_RANGE
X 0
DATA_TYPE 8
LENGTH 8 times the number of address ranges in the list.
A length of 0 indicates any address.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LOWER BOUND DST ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UPPER BOUND DST ADDRESS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sanchez, Condell [page 54]
Internet Draft Security Policy Protocol January 2002
LOWER BOUND DST ADDRESS
An IPV4 address representing the includsive lower-bound
of a range of destination addresses of a communication.
UPPER BOUND DST ADDRESS
An IPV4 address representing the includsive upper-bound
of a range of destination addresses of a communication.
A.9 SRC_IPV6_ADDR
X 0
DATA_TYPE 9
LENGTH 16 times the number of addresses in the list.
A length of 0 indicates any address.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SRC |
| ADDRESS |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SRC ADDRESS
An IPV6 address representing the source host of a
communication
A.10 SRC_IPV6_ADDR_SUBNET
X 0
DATA_TYPE 10
LENGTH 32 times the number of subnets in the list.
A length of 0 indicates any subnet.
list Yes
DATA_VALUE
Sanchez, Condell [page 55]
Internet Draft Security Policy Protocol January 2002
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SUBNET |
| ADDRESS |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SUBNET |
| MASK |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SUBNET ADDRESS
An IPV6 address representing the source subnet of a
communication
SUBNET MASK
An IPV6 address representing the source subnet mask of a
communication
A.11 SRC_IPV6_ADDR_RANGE
X 0
DATA_TYPE 11
LENGTH 32 times the number of address ranges in the list.
A length of 0 indicates any address.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| LOWER BOUND |
| SRC ADDRESS |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| UPPER BOUND |
| SRC ADDRESS |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
LOWER BOUND SRC ADDRESS
An IPV6 address representing the includsive lower-bound
of a range of source addresses of a communication.
Sanchez, Condell [page 56]
Internet Draft Security Policy Protocol January 2002
UPPER BOUND SRC ADDRESS
An IPV6 address representing the includsive upper-bound
of a range of source addresses of a communication.
A.12 DST_IPV6_ADDR
X 0
DATA_TYPE 12
LENGTH 16 times the number of addresses in the list.
A length of 0 indicates any address.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| DST |
| ADDRESS |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DST ADDRESS
An IPV6 address representing the destination host of a
communication
A.13 DST_IPV6_ADDR_SUBNET
X 0
DATA_TYPE 13
LENGTH 32 times the number of subnets in the list.
A length of 0 indicates any subnet.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SUBNET |
| ADDRESS |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| SUBNET |
| MASK |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sanchez, Condell [page 57]
Internet Draft Security Policy Protocol January 2002
SUBNET ADDRESS
An IPV6 address representing the destination subnet of a
communication
SUBNET MASK
An IPV6 address representing the destination subnet mask
of a communication
A.14 DST_IPV6_ADDR_RANGE
X 0
DATA_TYPE 14
LENGTH 32 times the number of address ranges in the list.
A length of 0 indicates any address.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| LOWER BOUND |
| DST ADDRESS |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| UPPER BOUND |
| DST ADDRESS |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
LOWER BOUND DST ADDRESS
An IPV6 address representing the includsive lower-bound
of a range of destination addresses of a communication.
UPPER BOUND DST ADDRESS
An IPV6 address representing the includsive upper-bound
of a range of destination addresses of a communication.
A.15 DIRECTION
X 1
DATA_TYPE 15
LENGTH TV attribute, no length
list No
DATA_VALUE
Sanchez, Condell [page 58]
Internet Draft Security Policy Protocol January 2002
1 2 3
6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DIRECTION |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DIRECTION
In/Outbound 0
Inbound 1
Outbound 2
Direction is with respect to the senders interface.
A.16 USER_NAME
X 0
DATA_TYPE 16
LENGTH 1 plus the length of NAME
A length of 0 indicates any name.
list No
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TYPE | NAME ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
NAME_TYPE
822_EMAIL 0
DIST_NAME 1
values 2-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
NAME
Name of type NAME_TYPE:
NAME_TYPE Description of NAME
822_EMAIL A fully-qualified user name string
(e.g. "jdoe@example.com") as defined in
RFC 822. The string must not contain
any terminators
DIST_NAME A fully-qualified distinguished name string
(e.g. "CN=John Doe, O=Example, Inc, C=US ")
as defined in RFC 1779. The string must not
contain any terminators
Sanchez, Condell [page 59]
Internet Draft Security Policy Protocol January 2002
A.17 SYSTEM_NAME
X 0
DATA_TYPE 17
LENGTH 1 plus the length of NAME
A length of 0 indicates any name.
list No
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NAME_TYPE | NAME ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
NAME_TYPE
DNS_NAME 0
DIST_NAME 1
822_NAME 2
X400_ADDR 3
DIR_NAME 4
EDI_PARTY_NAME 5
URI 6
IPADDR 7
REGID 8
OTHER 250
values 9-249 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
NAME
Name of type NAME_TYPE. Strings must not contain any
terminators.
NAME_TYPE Description of NAME
DNS_NAME A DNS name string (e.g. "host.example.com")
as defined in RFC 1034.
DIST_NAME A fully-qualified distinguished name string
(e.g. "CN=John Doe, O=Example Inc, C=US ")
as defined in RFC 1779.
822_EMAIL A fully-qualified user name string
(e.g. "jdoe@example.com") as defined in
RFC 822.
X400_ADDR A textual representation of an X.400 OR
address string
(e.g. "/CN=John Doe/O=Example Inc/C=US/")
as defined in RFC 2156.
Sanchez, Condell [page 60]
Internet Draft Security Policy Protocol January 2002
DIR_NAME A relative distinguished name string
(e.g. "OU=Engineering + CN=John Doe,
O=Example Inc, C=US ") as defined in RFC 1779.
EDI_PARTY_NAME An electronic data interchange name string.
URI A uniform resource identifier string
(e.g. "ftp://ftp.example.com/pub/doc.html")
as defined in RFC 2396.
IPADDR A 32-bit or 128-bit IP address. Note that
this is NOT the string representation of
the IP address.
REGID A registered ID is represented by a string
representation of the dotted integer
representation of an object ID (OID)
(e.g. "4.5.8.2.1").
OTHER This is an object identifier followed by
object specific information. The OID is
represented as above, however, its end is
indicated by a colon ":" which is followed
by the object specified information.
(e.g. "4.5.8.2.1:" 98 "jdoe")
A.18 XPORT_PROTOCOL
X 0
DATA_TYPE 18
LENGTH 1 plus length of pdata
A length of 0 indicates any address.
list No (see below)
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PTYPE | PDATA ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PTYPE Describes the rest of the data:
ANY 0
OPAQUE 1
LIST 2
RANGE 3
PDATA
Not used if PTYPE is ANY or OPAQUE.
LIST
indicates a list whose elements look like the following:
Sanchez, Condell [page 61]
Internet Draft Security Policy Protocol January 2002
0
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| PROTOCOL |
+-+-+-+-+-+-+-+-+
The length of pdata to be used as part of the LENGTH
field is 1 times the number of elements in the list.
RANGE
indicates a range of protocol values whose inclusive
lower-bound is LOWER, and inclusive upper-bound is UPPER.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LOWER | UPPER |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The length of pdata to be used as part of the LENGTH
field is 2.
A.19 SRC_PORT
X 0
DATA_TYPE 19
LENGTH 2 times the number of ports in the list.
A length of 0 indicates any port.
list Yes
DATA_VALUE
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PORT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PORT
Port that the communication must be initiated with. This
may be a list of ports.
A.20 SRC_PORT_DYNAMIC
X 0
DATA_TYPE 20
LENGTH 4 plus 2 times the number of ports in the list.
A length of 4 indicates any port.
list See Below
DATA_VALUE
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DYNAMIC LOWER BOUND | DYNAMIC UPPER BOUND |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PORT | ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The use of this attribute indicates that dynamic port allocation
is permitted. Communications that are intitiated with any of the
ports indicated, may then dynamically allocate any of the ports
listed within the LOWER and UPPER BOUNDS, inclusive.
DYNAMIC LOWER BOUND
Lower bound of the range of ports that may be dynamically
allocated. If this and DYNAMIC UPPER BOUND are both 0,
then any port may be dynamically allocated.
DYNAMIC UPPER BOUND
Upper bound of the range of ports that may be dynamically
allocated. If this and DYNAMIC LOWER BOUND are both 0,
then any port may be dynamically allocated.
PORT
Port that the communication must be initiated with. This
may be a list of ports.
A.21 DST_PORT
X 0
DATA_TYPE 21
LENGTH 2 times the number of ports in the list.
A length of 0 indicates any port.
list Yes
DATA_VALUE
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PORT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PORT
Port that the communication must be initiated with. This
may be a list of ports.
A.22 DST_PORT_DYNAMIC
X 0
DATA_TYPE 22
LENGTH 4 plus 2 times the number of ports in the list.
A length of 4 indicates any port.
list See Below
DATA_VALUE
Sanchez, Condell [page 63]
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DYNAMIC LOWER BOUND | DYNAMIC UPPER BOUND |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PORT | ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The use of this attribute indicates that dynamic port allocation
is permitted. Communications that are intitiated with any of the
ports indicated, may then dynamically allocate any of the ports
listed within the LOWER and UPPER BOUNDS, inclusive.
DYNAMIC LOWER BOUND
Lower bound of the range of ports that may be dynamically
allocated. If this and DYNAMIC UPPER BOUND are both 0,
then any port may be dynamically allocated.
DYNAMIC UPPER BOUND
Upper bound of the range of ports that may be dynamically
allocated. If this and DYNAMIC LOWER BOUND are both 0,
then any port may be dynamically allocated.
PORT
Port that the communication must be initiated with. This
may be a list of ports.
A.23 SEC_LABELS
X 0
DATA_TYPE 23
LENGTH Variable.
list No
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SECURITY LABEL ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SECURITY LABEL
Bit representation of the security label for the IP
security option field.
A.24 V6CLASS
X 1
DATA_TYPE 24
LENGTH TV attribute, no length
list No
DATA_VALUE
Sanchez, Condell [page 64]
Internet Draft Security Policy Protocol January 2002
1 2 3
6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PADDING | CLASS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PADDING
set to 0
CLASS
class value
A.25 V6FLOW
X 0
DATA_TYPE 25
LENGTH 4
list No
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PADDING | FLOW |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PADDING
set to 0
FLOW
set to flow value
A.26 V4TOS
X 1
DATA_TYPE 26
LENGTH TV attribute, no length
list No
DATA_VALUE
1 2 3
6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PADDING | TOS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PADDING
set to 0
Sanchez, Condell [page 65]
Internet Draft Security Policy Protocol January 2002
TOS
type of service value
A.27 ACTION
X 1
DATA_TYPE 27
LENGTH TV attribute, no length
list No
DATA_VALUE
1 2 3
6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACTION |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ACTION
Deny 0
Permit 1
A.28 SRC_PORT_RANGE
X 0
DATA_TYPE 28
LENGTH 4 times the number of port ranges in the list.
A length of 0 indicates any port.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PORT LOWER BOUND | PORT UPPER BOUND |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PORT LOWER BOUND
Inclusive lower-bound of a range of port numbers that the
communication must be initiated with.
PORT UPPER BOUND
Inclusive upper-bound of a range of port numbers that the
communication must be initiated with.
Sanchez, Condell [page 66]
Internet Draft Security Policy Protocol January 2002
A.29 DST_PORT_RANGE
X 0
DATA_TYPE 29
LENGTH 4 times the number of port ranges in the list.
A length of 0 indicates any port.
list Yes
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PORT LOWER BOUND | PORT UPPER BOUND |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PORT LOWER BOUND
Inclusive lower-bound of a range of port numbers that the
communication must be initiated with.
PORT UPPER BOUND
Inclusive upper-bound of a range of port numbers that the
communication must be initiated with.
A.30 IPSEC_ACTION
X 0
DATA_TYPE 50
LENGTH Variable
list Yes
DATA_VALUE
Sanchez, Condell [page 67]
Internet Draft Security Policy Protocol January 2002
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -----
| ESP | RESERVED | LIFETIME_TYPE | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| LIFETIME | Fixed
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Length
| AH | IPCOMP | LIFETIME_TYPE | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| LIFETIME | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -----
| N_OF_CIPHERS | CIPHER_ALG | CIPHER_KEYLENGTH
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ROUNDS | ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| N_OF_INT_ESP | INT_ALG_ESP | ESP_INT_KEYLENGTH ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| N_OF_INT_AH | INT_ALG_AH | INT_KEYLENGTH ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| N_OF_IPCOMP | IPCOMP_ALG ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| N_OF_LOCATIONS|E|P| LOC_TYPE | LOCATION...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
ESP
This octet indicates if ESP is to be used and in what
mode. NOT REQUIRED means that ESP is not necessary but if used
it MUST be negotiated based on the parameters defined
below. TUNNEL_MODE or TRANSP_MODE means that ESP MUST be
negotiatiated in this mode. ANY_MODE means that ESP MUST be
negotited and that any mode (Tunnel or transport) will
suffice. NOT ALLOWED means that ESP SHOULD NOT be negotiated
and it MUST NOT be part of this SA.
NOT_REQUIRED 0
TUNNEL_MODE 1
TRANSP_MODE 2
TUNNEL_MODE_OPT 3
TRANSP_MODE_OPT 4
ANY_MODE 5
NOT ALLOWED 6
LIFETIME_TYPE
This 2 octet field indicates type of lifetime.
RESERVED 0
SECONDS 1
KILOBYTES 2
These values are assigned in section 4.5 of [Piper98] and
are updated when those assigned values change.
Sanchez, Condell [page 68]
Internet Draft Security Policy Protocol January 2002
RESERVED
This 1 octet field primarily used for alignment purposes. Its
value is always 0.
LIFETIME
This 4 octet field indicates the SA lifetime. For a given
"Lifetime_Type" the value of the "Lifetime" attribute
defines the actual length of the SA life--either a number of
seconds, or a number of kilobytes protected. 0 is not used.
AH
This octet indicates if AH is to be used and in what mode. NOT
REQUIRED means that AH is not necessary but if used it MUST be
negotiated based on the parameters defined below. TUNNEL_MODE or
TRANSP_MODE means that AH MUST be negotiatiated in this
mode. ANY_MODE means that AH MUST be negotited and that any
mode (Tunnel or transport) will suffice. NOT
ALLOWED means that AH SHOULD NOT be negotiated and it MUST
not be part of this SA.
NOT_REQUIRED 0
TUNNEL_MODE 1
TRANSP_MODE 2
TUNNEL_MODE_OPT 3
TRANSP_MODE_OPT 4
ANY_MODE 5
NOT ALLOWED 6
IPCOMP
This field indicates if IP Compression is to be used. NOT
REQUIRED means that IPCOMP is not necessary but if used it MUST
be negotiated based on the parameters defined below. REQUIRED
means that IPCOMP MUST be negotiated as part of this SA. NOT
ALLOWED means that IPCOMP MUST NOT be part of this SA.
NOT_REQUIRED 0
REQUIRED 1
NOT ALLOWED 2
N_OF_CIPHERS
This octet indicates the number of CIPHER_ALG fields in octets
that will follow this field and that could be used during an
IKE phase 2 negotiation. If the value of the ESP
field is (04)hex this field MUST be set to 0.
Sanchez, Condell [page 69]
Internet Draft Security Policy Protocol January 2002
CIPHER_ALG
This octet indicates which ciphers should be used for the IKE
phase 2 negotiation. If the ANY identifier is used, it MUST be
the only identifier in the list, and its meaning does not
include the NULL cipher. If the value of the N_OF_CIPHERS
field is 0 the CIPHER_ALG, the CIPHER_KEYLENTH and the ROUNDS
fields are ignored.
ANY 0
NULL 1
RFC1829_IV64 2
DES 3
DES3 4
RC5 5
IDEA 6
CAST 7
BLOWFISH 8
3IDEA 9
RFC1829_IV32 10
RC4 11
These values are assigned in section 4.4.4 of [Piper98], with
the exception of 0 being defined as ANY, and are updated when
those assigned values change.
CIPHER_KEYLENGTH
The first octet corresponds to the minimum value and the
second octet corresponds to the maximum value. If no range
exist the first octet indicates the keylength. The second
octet contains a value of (00)hex.
ROUNDS
The first octet corresponds to the minimum value and the
second octet corresponds to the maximum value. If no range
exist the first octet indicates the rounds. The second
octet contains a value of (00)hex.
N_OF_INT_ESP
This octet indicates the number of INTEGRITY_ALG fields in
octets that will follow this field and that could be used
during an IKE phase 1 negotiation. If this field is 0 no
authentication/integrity is used with ESP.
INT_ALG_ESP
This octet indicates which algorithm should be used for the
IKE phase 2 negotiation. If the ANY identifier is used, it
MUST be the only identifier in the list. If the value of the
N_OF_INT_ESP field is 0 this INT_ALG_ESP and ESP_INT_KEYLENGTH
are ignored.
Sanchez, Condell [page 70]
Internet Draft Security Policy Protocol January 2002
ANY 0
HMAC_MD5 1
HMAC_SHA1 2
DES_MAC 3
KPDK 4
These values are assigned in section 4.5 of [Piper98], with
the exception of 0 being defined as ANY, and are updated when
those assigned values change.
ESP_INT_KEYLENGTH
The first octet corresponds to the minimum value and the
second octet corresponds to the maximum value. If no range
exist the first octet indicates the keylength. The second
octet contains a value of (00)hex.
N_OF_INT_AH
This octet indicates the number of INTEGRITY_ALG fields in
octets that will follow this field and that could be used
during an IKE phase 1 negotiation. If the value of the AH
field is (04)hex this field MUST be set to 0.
INT_ALG_AH
This octet indicates which algorithm should be used for the
IKE phase 2 negotiation. If the value of the N_OF_INT_AH
field is 0 the INT_ALG_AH and the INT_KEYLENGTH fields are
ignored.
ANY 0
HMAC_MD5 1
HMAC_SHA1 2
DES_MAC 3
KPDK 4
These values are assigned in section 4.5 of [Piper98], with
the exception of 0 being defined as ANY, and are updated when
those assigned values change.
INT_ KEYLENGTH
The first octet corresponds to the minimum value and the
second octet corresponds to the maximum value. If no range
exist the first octet indicates the keylength. The second
octet contains a value of (00)hex.
Sanchez, Condell [page 71]
Internet Draft Security Policy Protocol January 2002
N_OF_IPCOMP
This octet indicates the number of IPCOMP_ALG fields in octets
that will follow this field and that could be used during an
IKE phase 2 negotiation. If the value of the IPCOMP
field is (04)hex this field MUST be set to 0.
IPCOMP_ALG
This octet indicates which algorithm should be used for the
IKE phase 2 negotiation. If the ANY identifier is used, it
MUST be the only identifier in the list. If the value of the
N_OF_IPCOMP field is 0 this field is ignored.
ANY 0
OUI 1
DEFLATE 2
LZS 3
These values are assigned in section 4.4.5 of [Piper98], with
the exception of 0 being defined as ANY, and are updated when
those assigned values change.
N_OF_LOCATIONS
This octet indicates the number of E/P/LOC_TYPE fields
that will follow this field.
E
This bit indicates whether this location represents a
source or destination location. E = 0 indicates a source
location and E = 1 indications a destination location.
P
This bit indicates whether the location is for the AH or ESP
SA. P = 0 indicates the location is for the AH SA while
P = 1 indicates the location is for the ESP SA.
LOC_TYPE
This 6-bit field indicates the contents of the LOCATION
field. If this field is 0 then the LOCATION will be omitted.
NONE 0
IPv4 address 1
IPv6 address 2
DNS Name 3
General 4
values 5-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
Sanchez, Condell [page 72]
Internet Draft Security Policy Protocol January 2002
LOCATION
Variable length field depending on LOC_TYPE.
IF LOC_TYPE is (04) then this field is 1 octet in length an it
may only take the following values:
ANY 0
DEST 1
HOST 2
LOCAL-SG 3
REMOTE-SG 4
values 5-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
If multiple locations are indicated that specify the same end-point
for the same SA (i.e. E and P bits are the same), it indicates that
they are possible alternatives for the end-point.
A.31 IKE_ACTION
X 0
DATA_TYPE 51
LENGTH Variable
list No
DATA_VALUE
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MODE |P|GR| RESERVED | FIELD SIZE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PRF | LIFETIME_TYPE |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LIFETIME |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| N_OF_AUTH | AUTH_METHOD ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| N_OF_CIPHERS | CIPHER_ALG | KEYLENGTH...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| N_OF_HASH | HASH_ALG ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GROUP...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sanchez, Condell [page 73]
Internet Draft Security Policy Protocol January 2002
MODE
This octet indicates the IKE mode of operation.
MAIN 0
AGRESSIVE 1
QUICK 2
values 3-250 are reserved to IANA. Values 251-255 are for
private use among mutually consenting parties.
P
Indicates if PFS is to be used for the SA negotiation.
FALSE 0
TRUE 1
GR
Indicates if a group description or group type fields are
included in this IKE action.
NO GROUP 0
GROUP_DESCRIPTION 1
GROUP_TYPE 2
See the GROUP field below for more information.
RESERVED
Reserved for future use. Set to zero.
FIELD SIZE
The field size, in bits, of a Diffie-Hellman Group
PRF
There are currently no pseudo-random functions defined.
These values are assigned in Appendix A of [Harkins98]
and are updated when those assigned values change.
LIFETIME_TYPE
This 2 octet field indicates type of lifetime.
seconds 1
kilobytes 2
These values are assigned in Appendix A of [Harkins98]
and are updated when those assigned values change.
Sanchez, Condell [page 74]
Internet Draft Security Policy Protocol January 2002
LIFETIME
This 4 octet field indicates the SA lifetime. For a given
"Lifetime_Type" the value of the "Lifetime" attribute defines
the actual length of the SA life-- either a number of seconds,
or a number of kilobytes protected.
N_OF_AUTH
This octet indicates the number of AUTH_METHOD fields in octets
that will follow this field and that could be used during an
IKE phase 1 negotiation.
AUTH_METHOD
This octet indicates which authentication methods should be
used. The number of auth_methods that could be used is N_OF_AUTH
pre-shared key 1
DSS signatures 2
RSA signatures 3
Encryption with RSA 4
Revised encryption with RSA 5
These values are assigned in Appendix A of [Harkins98]
and are updated when those assigned values change.
N_OF_CIPHERS
This octet indicates the number of CIPHER_ALG fields in octets
that will follow this field and that could be used during an
IKE phase 1 negotiation.
KEYLENGTH
The first octet corresponds to the minimum value and the
second octet corresponds to the maximum value. If no range
exist the first octet indicates the keylength. The second
octet contains a value of (00)hex.
CIPHER_ALG
This octet indicates which ciphers should be used for the IKE
phase 1 negotiation. For IKE phase 2 negotiations this field is
ignored. The number of ciphers that could be used is
N_OF_CIPHERS
ANY 0
DES 1
IDEA 2
BLOWFISH 3
RC5 4
DES3 5
CAST 6
Sanchez, Condell [page 75]
Internet Draft Security Policy Protocol January 2002
These values are assigned in Appendix A of [Harkins98], with
the exception of 0 being defined as ANY, and are updated when
those assigned values change.
N_OF_HASH
This octet indicates the number of HASH_ALG fields in octets
that will follow this field and that could be used during an
IKE phase 1 negotiation.
HASH_ALG
This octet indicates which algorithm should be used for the
IKE phase 1 negotiation. For IKE phase 2 negotiations this
field is ignored.
ANY 0
MD5 1
SHA1 2
TIGER 3
These values are assigned in Appendix A of [Harkins98], with
the exception of 0 being defined as ANY, and are updated when
those assigned values change.
GROUP
This field describes the group to be used during ISAKMP
negotiation. It is only present if GR is 1 or 2. If GR
is 1 it takes the form of the GROUP_DESCRIPTION field below.
If it is 2, it takes the form of the GROUP_DEFINITION field
below.
GROUP DESCRIPTION
1 2 3
6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ACTION |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This 2 octet field indicates which group should be used during
the ISAKMP phase 1 or phase 2 negotiation.
Not Used 0
default 768-bit MODP group 1
alternate 1024-bit MODP group 2
EC2N group on GP[2^155] 3
EC2N group on GP[2^185] 4
These values are assigned in Appendix A of [Harkins98]
and are updated when those assigned values change.
Sanchez, Condell [page 76]
Internet Draft Security Policy Protocol January 2002
GROUP DEFINITION
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GROUP TYPE | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PRIME LENGTH | PRIME
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GENERATOR 1 LENGTH | GENERATOR 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GENERATOR 2 LENGTH | GENERATOR 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CURVE A LENGTH | CURVE A
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CURVE B LENGTH | CURVE B
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GROUP LENGTH | GROUP
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
GROUP TYPE
This 2 octet field indicates which group type should be used
during the ISAKMP phase 1 or phase 2 negotiation.
Not Used 0
MODP 1
ECP 2
EC2N 3
These values are assigned in Appendix A of [Harkins98]
and are updated when those assigned values change.
RESERVED
Reserved for future use. Set to zero.
PRIME LENGTH
GENERATOR 1 LENGTH
GENERATOR 2 LENGTH
CURVE A LENGTH
CURVE B LENGTH
GROUP LENGTH
Length of their respective fields in bytes. If their
respective field does not exist, the length is set to zero.
PRIME
GENERATOR 1
GENERATOR 2
CURVE A
CURVE B
GROUP
Sanchez, Condell [page 77]
Internet Draft Security Policy Protocol January 2002
The group prime/irreducible polynomial, group generator one,
group generator two, group curve A, group curve B, and group
order, respectively. These are defined in [Harkins98].
APPENDIX B
An SPP Example
This appendix provides a detailed example of SPP in use.
admin. boundary admin. boundary
----------------- ---------------------------
| | | admin. boundary|
| | | ---------------|
| Q1 | Q2 | Q3 | ||
| H1 ---- SG1 ---- (Internet) --- SG2 ---- | SG3 --- H2 ||
| R3 | | R2 | | R1 | | ||
| PS1 | | PS2 | PS3 ||
| | | ---------------|
----------------- ---------------------------
ESP Tunnel
|=======================|
ESP Tunnel
|========================================|
ESP Transport
|================================================|
|==| = security association required by policy
---- = connectivity (or if so labeled, administrative boundary)
Hx = host x
SGx = security gateway x
PSx = policy server x
Qx = query x
Rx = reply x
The following entities have these policies for a communication
between H1 and H2 for UDP port 79:
H1: requires an ESP Transport SA with H2
PS1: requires an ESP Tunnel SA between SG1 and SG2
PS2: requires an ESP Tunnel SA between SG1 and SG2
PS3: requires an ESP Tunnel SA between H1 and SG3
H2: requires an ESP Transport SA with H1
PS1, PS2, PS3 also have policies allowing ESP to pass through
their respective Security Gateways.
1. The policy client at H1 is asked for a policy for a communication:
H1 to H2 using UDP port 79.
Sanchez, Condell [page 78]
Internet Draft Security Policy Protocol January 2002
2. H1's policy client does not have an answer so it creates an SPP
query, Q1:
SPP Header [Query, Sender H1, qcount 1, rcount 2]
Query Payload [comsec]:
src H1, dst H2, UDP, 79
Record Payload [comsec]:
src H1, dst H2, UDP, 79, permit
Record Payload [SA rec]:
src H1, dst H2, UDP, 79, permit, ESP transport H1->H2
Signature Payload
H1 sends Q1 to PS1, its configured policy server.
3. PS1 receives the query and verifies the signature. Its domain
database indicates that it is not authoritative over H2 so it
checks its cache to see if it has a cached answer. For this
example, it does not, so it creates a new SPP query, Q2, with
the query and records formed by merging the local policy with
the policy from Q1:
SPP Header [Query, Sender PS1, qcount 1, rcount 3]
Query Payload [comsec]:
src H1, dst H2, UDP, 79
Record Payload [comsec]:
src H1, dst H2, UDP, 79, permit
Record Payload [SA rec]:
src SG1, dst SG2, UDP, 79, permit, ESP tunnel SG1->SG2
Record Payload [SA rec]:
src H1, dst H2, UDP, 79, permit, ESP transport H1->H2
Signature Payload
PS1 sends Q2 to H2.
4. SG2 intercepts Q2 and passes it to PS2.
5. PS2 receives the query and verifies the signature. Its domain
database indicates that it is not authoritative over H2 so it
checks its cache to see if it has a cached answer. For this
example, it does not, so it creates a new SPP query, Q3, with
the query and records formed by merging the local policy with
the policy from Q2:
SPP Header [Query, Sender PS1, qcount 1, rcount 3]
Query Payload [comsec]:
src H1, dst H2, UDP, 79
Record Payload [comsec]:
src H1, dst H2, UDP, 79, permit
Record Payload [SA rec]:
src SG1, dst SG2, UDP, 79, permit, ESP tunnel SG1->SG2
Record Payload [SA rec]:
src H1, dst H2, UDP, 79, permit, ESP transport H1->H2
Signature Payload
PS2 sends Q3 to H2.
6. SG3 intercepts Q3 and passes it to PS3.
Sanchez, Condell [page 79]
Internet Draft Security Policy Protocol January 2002
7. PS3 receives the query and verifies the signature. Its domain
database indicates that it is authoritative over H2 so it
will send a reply. It checks its cache to see if it has a cached
answer. For this example, it does have one cached from previous
information sent to it by H2. PS3 merges the cached policy with
the policy it received from Q3. The merge indicates that a signal
and a reply will be needed. PS3 caches the merged policy.
PS3 creates a reply with the query payload from Q3, the merged
policy and policy server and cert records:
SPP Header [Reply, Sender PS3, qcount 1, rcount 6]
Query Payload [comsec]:
src H1, dst H2, UDP, 79
Record Payload [comsec]:
src H1, dst H2, UDP, 79, permit
Record Payload [SA rec]:
src SG1, dst SG2, UDP, 79, permit, ESP tunnel SG1->SG2
Record Payload [SA rec]:
src H1, dst SG3, UDP, 79, permit, ESP tunnel H1->SG3
Record Payload [SA rec]:
src H1, dst H2, UDP, 79, permit, ESP transport H1->H2
Record Payload [policy server]:
policy server PS3, node H2
Record Payload [cert]:
cert for PS3
Signature Payload
PS3 sends R1 to PS2.
PS3 creates a signal with a comsec record derived from knowing the
traffic that will pass through SG3 and, the part of the merged
policy that terminates at SG3:
SPP Header [Pol, Sender PS3, qcount 0, rcount 2]
Record Payload [comsec]:
src H1, dst H2, ESP, OPAQUE, permit
Record Payload [SA rec]:
src H1, dst SG3, UDP, 79, permit, ESP tunnel H1->SG3
Signature Payload
PS3 sends the signal to SG3.
8. SG3 receives the signal and verifies the signature. SG3 creates
an Ack message to indicate that it has received the policy message:
SPP Header [Pol-Ack, Sender SG3, qcount 0, rcount 0]
Signature Payload
SG3 sends the signal to PS3.
9. PS3 receives the Pol-Ack and verifies the signature. PS3 removes
the corresponding policy message from its retry queue.
Sanchez, Condell [page 80]
Internet Draft Security Policy Protocol January 2002
10. Meanwhile, PS2 receives the reply R1 and verifies the signature and
the chain-of-trust to verify the policy came from a server
authoritative for H2. It matches an outstanding query message, so it
will send a reply. PS2 merges the policy received in R1 with its
local policy and the policy information it received from Q2. The
merge indicates that a signal and a reply will be needed. PS2
caches the merged policy.
PS2 creates a reply with the query payload from R1, the merged
policy and policy server and cert records:
SPP Header [Reply, Sender PS2, qcount 1, rcount 8]
Query Payload [comsec]:
src H1, dst H2, UDP, 79
Record Payload [comsec]:
src H1, dst H2, UDP, 79, permit
Record Payload [SA rec]:
src SG1, dst SG2, UDP, 79, permit, ESP tunnel SG1->SG2
Record Payload [SA rec]:
src H1, dst SG3, UDP, 79, permit, ESP tunnel H1->SG3
Record Payload [SA rec]:
src H1, dst H2, UDP, 79, permit, ESP transport H1->H2
Record Payload [policy server]:
policy server PS3, node H2
Record Payload [cert]:
cert for PS3
Record Payload [policy server]:
policy server PS2, node PS3
Record Payload [cert]:
cert for PS2
Signature Payload
PS2 sends R2 to PS1.
PS2 creates a signal with a comsec record derived from knowing the
traffic that will pass through SG2 and, the part of the merged
policy that terminates at SG2:
SPP Header [Pol, Sender PS2, qcount 0, rcount 2]
Record Payload [comsec]:
src H1, dst SG3, ESP, OPAQUE, permit
Record Payload [SA rec]:
src SG1, dst SG2, UDP, 79, permit, ESP tunnel SG1->SG2
Signature Payload
PS2 sends the signal to SG2.
11. SG2 receives the signal and verifies the signature. SG2 creates
an Ack message to indicate that it has received the policy message:
SPP Header [Pol-Ack, Sender SG2, qcount 0, rcount 0]
Signature Payload
SG2 sends the signal to PS2.
12. PS2 receives the Pol-Ack and verifies the signature. PS2 removes
the corresponding policy message from its retry queue.
Sanchez, Condell [page 81]
Internet Draft Security Policy Protocol January 2002
11. Meanwhile, PS1 receives the reply R2 and verifies the signature and
the chain-of-trust to verify the policy came from a server
authoritative for H2. R2 matches an outstanding query message, so it
will send a reply. PS1 merges the policy received in R2 with its
local policy and the policy information it received from Q1. The
merge indicates that a signal and a reply will be needed. PS1
caches the merged policy.
PS1 creates a reply with the query payload from R2 and the merged
policy. Policy server and cert records are not necessary since PS1
is authoritative for H1:
SPP Header [Reply, Sender PS1, qcount 1, rcount 3]
Query Payload [comsec]:
src H1, dst H2, UDP, 79
Record Payload [comsec]:
src H1, dst H2, UDP, 79, permit
Record Payload [SA rec]:
src H1, dst SG3, UDP, 79, permit, ESP tunnel H1->SG3
Record Payload [SA rec]:
src H1, dst H2, UDP, 79, permit, ESP transport H1->H2
Signature Payload
PS1 sends R3 to H1.
PS1 creates a signal with a comsec record derived from knowing the
traffic that will pass through SG1 and, the part of the merged
policy that terminates at SG1:
SPP Header [Pol, Sender PS1, qcount 0, rcount 2]
Record Payload [comsec]:
src H1, dst SG3, ESP, OPAQUE, permit
Record Payload [SA rec]:
src SG1, dst SG2, UDP, 79, permit, ESP tunnel SG1->SG2
Signature Payload
PS1 sends the signal to SG1.
12. SG1 receives the signal and verifies the signature. SG1 creates
an Ack message to indicate that it has received the policy message:
SPP Header [Pol-Ack, Sender SG1, qcount 0, rcount 0]
Signature Payload
SG1 sends the signal to PS1.
13. PS1 receives the Pol-Ack and verifies the signature. PS1 removes
the corresponding policy message from its retry queue.
14. Meanwhile, H1 receives the reply R3 and verifies the signature.
The client can now use the policy as it is needed.
Sanchez, Condell [page 82]
Internet Draft Security Policy Protocol January 2002
Appendix C
Decorrelation
It is not possible for a Policy Server to use policies as they are
written in the SPS master file, since those policies are likely to be
correlated. Two policies are correlated if there is a non-nil
intersection between the values of each of their selectors. Caching
correlated policies can lead to incorrect policy implementation based
on those cached policies, as the following example shows.
H1 --- SG1 --------- SG2 --- H2
| | \__ H3
| |
PS1 PS2
PS2 contains the following policies in its master file:
src dst proto direction action
1) * H2 * inbound permit
2) * * * inbound deny
These two policies are correlated since all the selectors (src, dst,
proto, and direction) overlap. The following SPP exchanges occur:
1) PS1 requests policy for H3.
2) PS2 returns policy #2 to PS1 which then caches policy #2.
3) PS1 now looks up the policy for H2 and discovers that it already
has a matching policy (policy #2) and uses that.
This is clearly wrong, since policy #2 indicates that the
communication to H2 should be denied, though PS2's policy actually
indicates that it should be allowed.
The solution is to remove the ambiguities that may exist in
the master file. The policies of the master file MUST be decorrelated
before they are entered into the Local Policy Database. That is, the
policies must be rewritten so that for every pair of policies there
exists a selector for which there is a nil intersection between the
values in both of the policies.
The policies in the above example could be decorrelated as follows:
src dst proto direction action
1') * H2 * inbound permit
2') * not H2 * inbound deny
Now the exchange is a bit different:
1) PS1 requests policy for H3.
2) PS2 returns policy #2' to PS1 which then caches policy #2'.
3) PS1 now looks up the policy for H2, doesn't have a matching
policy, so it requests a policy for H2.
4) PS2 returns policy #1' to PS1 which then caches policy #1',
which is the correct policy for H2.
Sanchez, Condell [page 83]
Internet Draft Security Policy Protocol January 2002
All SPAs and SPRs, therefore, MUST decorrelate their master
files before using those policies for SPP. Once the policies are
decorrelated, there is no longer any ordering requirement on the
policies, since only one policy will match any requested
communication. The next section describes decorrelation in more
detail and presents an algorithm that may be used to implement
decorrelation.
C.1 Decorrelation Algorithm
The basic decorrelation algorithm takes each policy in a correlated
set of policies and divides it up into a set of policies using a tree
structure. Those of the resulting policies that are decorrelated with
the decorrelated set of policies are then added to that decorrelated
set.
The basic algorithm does not guarantee an optimal set of decorrelated
policies. That is, the policies may be broken up into smaller sets
than is necessary, though they will still provide all the necessary
policy information. Some extensions to the basic algorithm are
described later to improve this and improve the performance of the
algorithm.
C A set of ordered, correlated policies
Ci The ith policy in C.
U The set of decorrelated policies being built from C
Ui The ith policy in U.
A policy P may be expressed as a mapping of selector values to
actions:
Pi = Si1 x Si2 x ... x Sik -> Ai
1) Put C1 in set U as U1
For each policy Cj (j > 1) in C
2) If Cj is decorrelated with every policy in U, then add it to U.
3) If Cj is correlated with one or more policies in U, create a tree
rooted at the policy Cj that partitions Cj into a set of decorrelated
policies. The algorithm starts with a root node where no selectors
have yet been chosen.
A) Choose a selector in Cj, Scjn, that has not yet been chosen when
traversing the tree from the root to this node. If there are no
selectors not yet used, continue to the next unfinished branch
until all branches have been completed. When the tree is
completed, go to step D.
T is the set of policies in U that are correlated with the policy
to this node.
Sanchez, Condell [page 84]
Internet Draft Security Policy Protocol January 2002
The policy at this node is the policy formed by the selector
values of each of the branches between the root and this node.
Any selector values that are not yet represented by branches
assume the corresponding selector value in Cj, since the values
in Cj represent the maximum value for each selector.
B) Add a branch to the tree for each value of the selector Scjn that
appears in any of the policies in T. (If the value is a superset
of the value of Scjn in Cj, then use the value in Cj, since that
value represents the universal set.) Also add a branch for the
compliment of the union of all the values of the selector Scjn
in T. When taking the compliment, remember that the universal
set is the value of Scjn in Cj. A branch need not be created
for the nil set.
C) Repeat A and B until the tree is completed.
D) The policy to each leaf now represents a policy that is a subset
of Cj. The policies at the leaves completely partition Cj in
such a way that each policy is either completely overridden by
a policy in U, or is decorrelated with the policies in U.
Add all the decorrelated policies at the leaves of the tree to U.
5) Get next Cj and goto 2.
6) When all policies in C have been processed, then U will contain an
decorrelated version of C.
There are several optimizations that can be made to this algorithm.
A few of them are presented here.
It is possible to optimize, or at least improve, the amount of
branching that occurs by carefully choosing the order of the selectors
used for the next branch. For example, if a selector Scjn can be
chosen so that all the values for that selector in T are equal to or a
superset of the value of Scjn in Cj, then only a single branch need to
be created (since the compliment will be nil).
Branches of the tree do not have to proceed with the entire
decorrelation algorithm. For example, if a node represents a policy
that is decorrelated with all the policies in U, then there is no
reason to continue decorrelating that branch. Also, if a branch is
completely overridden by a policy in U, then there is no reason to
continue decorrelating the branch.
An additional optimization is to check to see if a branch is
overridden by one of the CORRELATED policies in set C that has already
been decorrelated. That is, if the branch is part of decorrelating
Cj, then check to see if it was overridden by a policy Cm, m < j.
This is a valid check, since all the policies Cm are already expressed
in U.
Sanchez, Condell [page 85]
Internet Draft Security Policy Protocol January 2002
Along with checking if a policy is already decorrelated in step 2,
check if Cj is overridden by any policy in U. If it is, skip it since
it is not relevant. A policy x is overridden by another policy y if
every selector in x is equal to or a subset of the corresponding
selector in policy y. Appendix A shows an example of applying the
algorithm to a set of correlated policies.
C.2 Decorrelation Example
This appendix section demonstrates the decorrelation algorithm and the
optimizations presented on a sample set of policies. We start with
the following set of correlated policies, set C:
src dst prot sport dport user sec level
C1 199.93/16 199.100.2/24 TCP * 22 lsanchez sec
C2 199.93/16 199.100.2/24 TCP * * lsanchez conf
C3 199.93/16 199.100.2/24 UDP * * lsanchez *
C4 199.93/16 199.100.2/24 UDP * 52 * *
C5 199.93/16 199.100.2/24 * * * * *
C6 * * * * * * *
C.2.1 policy C1
We start with policy C1:
src dst prot sport dport user sec level
C1: 199.93/16 199.100.2/24 TCP * 22 lsanchez sec
By step 1 of the algorithm, C1 is put directly into set U as policy
U1.
The current decorrelated policy set U is:
U1 199.93/16 199.100.2/24 TCP * 22 lsanchez sec
C.2.2 policy C2
Next, we look at policy C2:
src dst prot sport dport user sec level
C2: 199.93/16 199.100.2/24 TCP * * lsanchez conf
C2 is decorrelated with the policies already in U (U1) because the
security levels do not overlap. By step 2, C2 is added to U as U2.
The current decorrelated policy set U is:
U1 199.93/16 199.100.2/24 TCP * 22 lsanchez sec
U2 199.93/16 199.100.2/24 TCP * * lsanchez conf
C.2.3 policy C3
Next, we look at policy C3:
src dst prot sport dport user sec level
C3: 199.93/16 199.100.2/24 UDP * * lsanchez *
Sanchez, Condell [page 86]
Internet Draft Security Policy Protocol January 2002
C3 is decorrelated with the policies already in U (U1 and U2) because
it uses UDP while both policies in U use TCP. By step 2, C3 is added
to U as U3.
The current decorrelated policy set U is:
U1 199.93/16 199.100.2/24 TCP * 22 lsanchez sec
U2 199.93/16 199.100.2/24 TCP * * lsanchez conf
U3 199.93/16 199.100.2/24 UDP * * lsanchez *
C.2.4 policy C4
Next, we look at policy C4:
src dst prot sport dport user sec level
C4: 199.93/16 199.100.2/24 UDP * 52 * *
T = {U3} o
/ \
~lsanchez / \ (user) lsanchez
Policy C4 is correlated with policy U3 in U, so T = {U3}. First we
choose to decorrelate the user selector. The policy in T as the value
"lsanchez" for this selector, so we create a branch for "lsanchez" and
its compliment.
The lsanchez branch:
199.93/16 199.100.2/24 UDP * 52 lsanchez *
is overriden by the policy U3.
The compliment branch:
199.93/16 199.100.2/24 UDP * 52 ~lsanchez *
is decorrelated with T since ~lsanchez does not overlap any policies
in T. Since this branch is decorrelated, it is added to set U.
The current decorrelated policy set U is:
U1 199.93/16 199.100.2/24 TCP * 22 lsanchez sec
U2 199.93/16 199.100.2/24 TCP * * lsanchez conf
U3 199.93/16 199.100.2/24 UDP * * lsanchez *
U4 199.93/16 199.100.2/24 UDP * 52 ~lsanchez *
C.2.5 policy C5
Next, we look at policy C5:
src dst prot sport dport user sec level
C5: 199.93/16 199.100.2/24 * * * * *
Sanchez, Condell [page 87]
Internet Draft Security Policy Protocol January 2002
T = U o
_______/|\_______
~UDP,~TCP / | \ (prot) UDP
| o T=U3,U4
| TCP |\_________
| | \
| | lsanchez | (user) ~lsanchez
T=U1,U2 o o T = U4
/ \ (user) / \
~lsanchez / \ lsanchez ~52 / \ (dport) 52
|
T=U1,U2 o
_________/|\_________
~sec,~conf / | \ (sec label) conf
| sec
|
T = U1 o
/ \
~22 / \ (dport) 22
Policy C5 is correlated with all the policies currently in U, so
T = U. First we choose to decorrelate the protocol selector. The
policies in $T$ have the values ``UDP'' and ``TCP'' for this selector,
so we create a branch for each of them and a branch for the complement
of their union.
We can stop processing the complement branch:
199.93/16 199.100.2/24 ~UDP,~TCP * * * *
since it is decorrelated with T. This policy will be added to
the decorrelated set.
The "UDP" and "TCP" branches still require more processing since they
are both still correlated with policies in U. We will start by
processing the "UDP" branch. The policy through this branch is
correlated with policies U3 and U4, so T = {U3, U4}. We choose to
decorrelate on the user selector. The policies in T have "lsanchez"
and "~lsanchez" as their values for this selector so we create
branches for "lsanchez" and "~lsanchez." The compliment branch is
redundant to these branches.
We can stop processing the "lsanchez" branch:
199.93/16 199.100.2/24 UDP * * lsanchez *
since it is overridden by policy U3.
The "~lsanchez" branch, however, requires more processing since it is
correlated with policy U4 (T = {U4}). We choose to decorrelate on the
dport selector. The policy in T has "52" as its value for this
selector so we create a "52" branch and a branch for its compliment
"~52".
Sanchez, Condell [page 88]
Internet Draft Security Policy Protocol January 2002
We can stop processing the complement branch:
199.93/16 199.100.2/24 UDP * ~52 ~lsanchez *
since it is decorrelated with T. This policy will be added to
the decorrelated set.
We can also stop processing the "52" branch:
199.93/16 199.100.2/24 UDP * 52 ~lsanchez *
since it is overridden by U4.
Now we need to go back and process the "TCP" branch. The policy
through this branch is correlated with policies U1 and U2, so T = {U1,
U2}. We choose to decorrelate on the user selector. The policies in
T have "lsanchez" as their values for this selector so we create
branches for "lsanchez" and its compliment, "~lsanchez."
We can stop processing the complement branch:
199.93/16 199.100.2/24 TCP * * ~lsanchez *
since it is decorrelated with T. This policy will be added to
the decorrelated set.
The "~lsanchez" branch, however, requires more processing since it is
correlated with both policies in T. We choose to decorrelate on the
sec label selector. The policies in T have "sec" and "conf" as their
values for this selector so we create branches "sec", "conf", and the
complement of their union, "~sec,~conf"
We can stop processing the complement branch:
199.93/16 199.100.2/24 TCP * * lsanchez ~sec,~conf
since it is decorrelated with T. This policy will be added to
the decorrelated set.
We can stop processing the "conf" branch:
199.93/16 199.100.2/24 TCP * * lsanchez conf
since it is overridden by policy U2.
The "sec" branch, however, requires more processing since it is
correlated with policy U1 (T = U1). We choose to decorrelate on the
dport selector. The policy in T has "22" as its value for this
selector so we create a "22" branch and a "~22" branch for its
compliment.
We can stop processing the complement branch:
199.93/16 199.100.2/24 TCP * ~22 lsanchez sec
since it is decorrelated with T. This policy will be added to
the decorrelated set.
We can stop processing the "22" branch:
199.93/16 199.100.2/24 TCP * 22 lsanchez sec
since it is overridden by policy U1.
Sanchez, Condell [page 89]
Internet Draft Security Policy Protocol January 2002
The decorrelated policy set after decorrelating C5 is:
U1 199.93/16 199.100.2/24 TCP * 22 lsanchez sec
U2 199.93/16 199.100.2/24 TCP * * lsanchez conf
U3 199.93/16 199.100.2/24 UDP * * lsanchez *
U4 199.93/16 199.100.2/24 UDP * 52 ~lsanchez *
U5 199.93/16 199.100.2/24 ~UDP,~TCP * * * *
U6 199.93/16 199.100.2/24 UDP * ~52 ~lsanchez *
U7 199.93/16 199.100.2/24 TCP * * ~lsanchez *
U8 199.93/16 199.100.2/24 TCP * * lsanchez ~sec,~conf
U9 199.93/16 199.100.2/24 TCP * ~22 lsanchez sec
C.2.6 policy C6
Finally, we look at policy C6:
src dst prot sport dport user sec level
C6: * * * * * * *
T = U o
/|
~199.93/16 / | (src) 199.93/16
T = U o
/|
~199.100.2/24 / | (dst) 199.100.2/24
Policy C6 is correlated with all the policies currently in U, so
T = U. First we choose to decorrelate the src selector. The
policies in $T$ have the value "199.93/16" for this selector,
so we create a branch for "199.93/16" and one for its compliment,
"~199.93/16".
We can stop processing the complement branch:
~199.93/16 * * * * * *
since it is decorrelated with all the policies in T. This policy will
be added to the decorrelated set.
The "199.93/16" branch, however, requires more processing since it is
correlated with all the policies in T. We choose to decorrelate on the
dst selector. The policies in T have "199.100.2/24" as their value
for this selector so we create a "199.100.2/24" branch and a
"~199.100.2/24" branch for its compliment.
We can stop processing the complement branch:
199.93/16 ~199.100.2/24 * * * * *
since it is decorrelated with all the policies in T. This policy will
be added to the decorrelated set.
We can stop processing the "199.100.2/24" branch:
199.93/16 199.100.2/24 * * * * *
since it is overridden by policy C5.
Sanchez, Condell [page 90]
Internet Draft Security Policy Protocol January 2002
The full decorrelated version of C is:
U1 199.93/16 199.100.2/24 TCP * 22 lsanchez sec
U2 199.93/16 199.100.2/24 TCP * * lsanchez conf
U3 199.93/16 199.100.2/24 UDP * * lsanchez *
U4 199.93/16 199.100.2/24 UDP * 52 ~lsanchez *
U5 199.93/16 199.100.2/24 ~UDP,~TCP * * * *
U6 199.93/16 199.100.2/24 UDP * ~52 ~lsanchez *
U7 199.93/16 199.100.2/24 TCP * * ~lsanchez *
U8 199.93/16 199.100.2/24 TCP * * lsanchez ~sec,~conf
U9 199.93/16 199.100.2/24 TCP * ~22 lsanchez sec
U10 199.93/16 ~199.100.2/24 * * * * *
U11 ~199.93/16 * * * * * *
Sanchez, Condell [page 91]
Internet Draft Security Policy Protocol January 2002
Disclaimer
The views and specification here are those of the authors and are
not necessarily those of their employers. The authors and their
employers specifically disclaim responsibility for any problems
arising from correct or incorrect implementation or use of this
specification.
Copyright (C) The Internet Society (2000). All
Rights Reserved.
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Author Information
Luis A. Sanchez Matthew N. Condell
Megisto Systems BBN Technologies
10 Moulton Street
Cambridge, MA 02138
USA USA
Email: lsanchez@megisto.com Email: mcondell@bbn.com
Telephone: Telephone: +1 (617) 873-6203
Sanchez, Condell [page 92]