NETCONF Working Group M. Badra
Internet-Draft DU
Obsoletes: 5539 (if approved) February 13, 2012
Intended status: Standards Track
Expires: August 16, 2012
NETCONF Over Transport Layer Security (TLS)
draft-badra-netconf-rfc5539bis-01
Abstract
The Network Configuration Protocol (NETCONF) provides mechanisms to
install, manipulate, and delete the configuration of network devices.
This document describes how to use the Transport Layer Security (TLS)
protocol to secure NETCONF exchanges. This document obsoletes RFC
5539.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 16, 2012.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
Badra Expires August 16, 2012 [Page 1]
Internet-Draft NETCONF over TLS February 2012
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions Used in This Document . . . . . . . . . . . . 3
2. NETCONF over TLS . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Connection Initiation . . . . . . . . . . . . . . . . . . 3
2.2. Connection Closure . . . . . . . . . . . . . . . . . . . . 4
3. Endpoint Authentication, Identification and Authorization . . 5
3.1. Server Identity . . . . . . . . . . . . . . . . . . . . . 5
3.2. Client Identity . . . . . . . . . . . . . . . . . . . . . 6
3.2.1. Deriving NETCONF Usernames From NETCONF Client
Certificates . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 16
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
7. Contributor's Address . . . . . . . . . . . . . . . . . . . . 18
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1. Normative References . . . . . . . . . . . . . . . . . . . 18
8.2. Informative References . . . . . . . . . . . . . . . . . . 19
Appendix A. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 19
A.1. From -00 to -01 . . . . . . . . . . . . . . . . . . . . . 19
A.2. From RFC5539 to draft-badra-netconf-rfc5539bis-00 . . . . 19
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 20
Badra Expires August 16, 2012 [Page 2]
Internet-Draft NETCONF over TLS February 2012
1. Introduction
The NETCONF protocol [RFC6241] defines a mechanism through which a
network device can be managed. NETCONF is connection-oriented,
requiring a persistent connection between peers. This connection
must provide integrity, confidentiality, peer authentication, and
reliable, sequenced data delivery.
This document defines "NETCONF over TLS", which includes support for
certificate and pre-shared key (PSK)-based authentication and key
derivation, utilizing the protected ciphersuite negotiation, mutual
authentication, and key management capabilities of the TLS (Transport
Layer Security) protocol, described in [RFC5246].
1.1. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. NETCONF over TLS
Since TLS is application-protocol-independent, NETCONF can operate on
top of the TLS protocol transparently. This document defines how
NETCONF can be used within a TLS session.
2.1. Connection Initiation
The peer acting as the NETCONF client MUST also act as the TLS
client. It MUST connect to the server that passively listens for the
incoming TLS connection on the TCP port 6513. It MUST therefore send
the TLS ClientHello message to begin the TLS handshake. Once the TLS
handshake has finished, the client and the server MAY begin to
exchange NETCONF data. In particular, the client will send complete
XML documents to the server containing <rpc> elements, and the server
will respond with complete XML documents containing <rpc-reply>
elements. The client MAY indicate interest in receiving event
notifications from a server by creating a subscription to receive
event notifications [RFC5277]. In this case, the server replies to
indicate whether the subscription request was successful and, if it
was successful, the server begins sending the event notifications to
the client as the events occur within the system.
All NETCONF messages MUST be sent as TLS "application data". It is
possible that multiple NETCONF messages be contained in one TLS
record, or that a NETCONF message be transferred in multiple TLS
records.
Badra Expires August 16, 2012 [Page 3]
Internet-Draft NETCONF over TLS February 2012
The previous version [RFC5539] of this document used the same framing
sequence defined in [RFC6242], under the assumption that it could not
be found in well-formed XML documents. However, this assumption is
not correct [RFC6242]. In order to solve this problem, and at the
same time be compatible with existing implementations, this document
uses the framing protocol defined in [RFC6242] as following :
The <hello> message MUST be followed by the character sequence
]]>]]>. Upon reception of the <hello> message, the receiving peer's
TLS Transport layer conceptually passes the <hello> message to the
Messages layer. If the :base:1.1 capability is advertised by both
peers, the chunked framing mechanism defined in Section 4.2 of
[RFC6242] is used for the remainder of the NETCONF session.
Otherwise, the old end-of-message-based mechanism (see Section 4.3 of
[RFC6242]) is used.
Implementation of the protocol specified in this document MAY
implement any TLS cipher suite that provides mutual authentication
[RFC5246].
Implementations MUST support TLS 1.2 [RFC5246] and are REQUIRED to
support the mandatory-to-implement cipher suite, which is
TLS_RSA_WITH_AES_128_CBC_SHA. This document is assumed to apply to
future versions of TLS; in which case, the mandatory-to-implement
cipher suite for the implemented version MUST be supported.
2.2. Connection Closure
A TLS client MUST close the associated TLS connection if the
connection is not expected to issue any NETCONF RPC commands later.
It MUST send a TLS close_notify alert before closing the connection.
The TLS client MAY choose to not wait for the TLS server close_notify
alert and simply close the connection, thus generating an incomplete
close on the TLS server side. Once the TLS server gets a
close_notify from the TLS client, it MUST reply with a close_notify
unless it becomes aware that the connection has already been closed
by the TLS client (e.g., the closure was indicated by TCP).
When no data is received from a connection for a long time (where the
application decides what "long" means), a NETCONF peer MAY close the
connection. The NETCONF peer MUST attempt to initiate an exchange of
close_notify alerts with the other NETCONF peer before closing the
connection. The close_notify's sender that is unprepared to receive
any more data MAY close the connection after sending the close_notify
alert, thus generating an incomplete close on the close_notify's
receiver side.
Badra Expires August 16, 2012 [Page 4]
Internet-Draft NETCONF over TLS February 2012
3. Endpoint Authentication, Identification and Authorization
3.1. Server Identity
During the TLS negotiation, the client MUST carefully examine the
certificate presented by the server to determine if it meets the
client's expectations. Particularly, the client MUST check its
understanding of the server hostname against the server's identity as
presented in the server Certificate message, in order to prevent man-
in-the-middle attacks.
Matching is performed according to the rules below (following the
example of [RFC4642]):
o The client MUST use the server hostname it used to open the
connection (or the hostname specified in the TLS "server_name"
extension [RFC5246]) as the value to compare against the server
name as expressed in the server certificate. The client MUST NOT
use any form of the server hostname derived from an insecure
remote source (e.g., insecure DNS lookup). CNAME canonicalization
is not done.
o If a subjectAltName extension of type dNSName is present in the
certificate, it MUST be used as the source of the server's
identity.
o Matching is case-insensitive.
o A "*" wildcard character MAY be used as the leftmost name
component in the certificate. For example, *.example.com would
match a.example.com, foo.example.com, etc., but would not match
example.com.
o If the certificate contains multiple names (e.g., more than one
dNSName field), then a match with any one of the fields is
considered acceptable.
If the match fails, the client MUST either ask for explicit user
confirmation or terminate the connection and indicate the server's
identity is suspect.
Additionally, clients MUST verify the binding between the identity of
the servers to which they connect and the public keys presented by
those servers. Clients SHOULD implement the algorithm in Section 6
of [RFC5280] for general certificate validation, but MAY supplement
that algorithm with other validation methods that achieve equivalent
levels of verification (such as comparing the server certificate
against a local store of already-verified certificates and identity
Badra Expires August 16, 2012 [Page 5]
Internet-Draft NETCONF over TLS February 2012
bindings).
If the client has external information as to the expected identity of
the server, the hostname check MAY be omitted.
3.2. Client Identity
The server MUST verify the identity of the client to ensure that the
incoming client request is legitimate before any configuration or
state data is sent to or received from the client.
The NETCONF protocol [RFC6241] requires that the transport protocol's
authentication process MUST result in an authenticated client
identity whose permissions are known to the server. The
authenticated identity of a client is commonly referred to as the
NETCONF username.
The username provided by the TLS implementation will be made
available to the NETCONF message layer as the NETCONF username
without modification. If the username does not comply to the NETCONF
requirements on usernames [RFC6241], i.e., the username is not
representable in XML, the TLS session MUST be dropped.
Algorithms for mapping certificates or PSK identities (sent by the
client) to NETCONF usernames are described below.
3.2.1. Deriving NETCONF Usernames From NETCONF Client Certificates
The algorithm for deriving NETCONF usernames from TLS certificates is
patterned after the algorithm for deriving tmSecurityNames from TLS
certificates specified in Transport Layer Security (TLS) Transport
Model for the Simple Network Management Protocol (SNMP) [RFC6353].
The NETCONF server MUST implement the algorithms for deriving NETCONF
usernames from presented certificates that are documented in the
ietf-netconf-tls YANG module. This YANG module lets the NETCONF
security administrator configure how the NETCONF server derives
NETCONF usernames from presented certificates. It also lets
different certificate-to-username derivation algorithms be used for
different certificates.
When a NETCONF server accepts a TLS connection from a NETCONF client,
the NETCONF server attempts to derive a NETCONF username from the
certificate presented by the NETCONF client. If the NETCONF server
cannot derive a valid NETCONF username from the client's presented
certificate, then the NETCONF server MUST close the TLS connection,
and MUST NOT accept NETCONF messages over it. The NETCONF server MAY
use any of the following algorithms to produce the NETCONF username
from the certificate presented by the NETCONF client:
Badra Expires August 16, 2012 [Page 6]
Internet-Draft NETCONF over TLS February 2012
o Map a certificate directly to a specified, pre-configured, NETCONF
username;
o Extract the subjectAltName's rfc822Name from the certificate, then
use the extracted rfc822Name as the NETCONF username;
o Extract the subjectAltName's dnsName from the certificate, then
use the extracted dnsName as the NETCONF username;
o Extract the subjectAltName's iPAddress from the certificate, then
use the extracted iPAddress as the NETCONF username;
o Examine the subjectAltName's rfc822Name, dnsName, and iPAddress
fields in a pre-defined order. Return the value from the first
subjectAltName field that is examined, defined, and populated with
a non-empty value. If no subjectAltName field of a specific type
is defined, then the examination skips that field and proceeds to
examine the next field type. If a subjectAltName field is
defined, but the value is not populated, or is populated by an
empty value, then the examination skips that field and proceeds to
examine the next field type.
The NETCONF server MUST implement all of these algorithms, and allow
the deployer to choose the algorithm used. The certificate-to-
username-transforms container in the ietf-netconf-tls YANG module
specifies how a NETCONF server transforms a certificate into a
NETCONF username.
3.2.1.1. Identifying a Certificate
A client certificate has an identity: the certificate. The TLS and
corresponding protocols provide an identity. The identity shows that
"this client certificate has shown that it, indeed, is on the other
side of the connection". With a complete certificate, the
certificate receiver can be certain that for someone or something on
the other side to use that certificate successfully, it has the
associated private key.
The problem with using the entire certificates as the identity is
that they are difficult for people to use. It is generally accepted
that a fingerprint of a certificate is not likely to come up with a
collision against a fingerprint of another (different) certificate.
Thus, assuming a good hash algorithm, a fingerprint can be a safe
short-hand for identifying a certificate.
If a locally held copy of a trusted CA certificate is configured in
the transformation container, and that CA certificate was used to
validate the path to the presented certificate, then the NETCONF
Badra Expires August 16, 2012 [Page 7]
Internet-Draft NETCONF over TLS February 2012
server SHOULD use that list entry in the transformation container.
All presented certificates validated by the configured CA certificate
will be transformed to NETCONF usernames using the same
transformation algorithm.
3.2.1.2. Deriving NETCONF Usernames From PSK identities
Implementations MAY optionally support TLS Pre-Shared Key (PSK)
authentication [RFC4279]. RFC4279 describes pre-shared key
ciphersuites for TLS. During the TLS Handshake, the client indicates
which key to use by including a "PSK identity" in the TLS
ClientKeyExchange message [RFC4279]. On the server side, this PSK
identity is used to look up the key corresponding to the presented
PSK identity. If the selected pre-shared keys match and the key is
valid, then the client is authenticated and the NETCONF username
associated with the PSK identity. For details on how the PSK
identity MAY be encoded in UTF-8, see section 5.1. of RFC [RFC6241].
3.2.1.3. Remote Configuration
The ietf-netconf-tls YANG module defines objects for remotely
configuring the mapping of TLS certficates and of PSK Identities to
NETCONF usernames.
module ietf-netconf-tls {
namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-tls";
prefix "nctls";
import ietf-yang-types {
prefix yang;
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
WG Chair: Mehmet Ersue
<mailto:mehmet.ersue@nsn.com>
WG Chair: Bert Wijnen
<mailto:bertietf@bwijnen.net>
Badra Expires August 16, 2012 [Page 8]
Internet-Draft NETCONF over TLS February 2012
Editor: Mohamad Badra
<mailto:mbadra@gmail.com>";
description
"This module applies to NETCONF over TLS. It specifies how
NETCONF servers transform X.509 certificates presented by
clients into NETCONF usernames. It also specifies how NETCONF
clients transform NETCONF usernames into X.509 certificates
for presentation to NETCONF servers.
This YANG module is patterned after, and closely models, parts of
the SNMP-TLS-TM-MIB defined in RFC 6353. Much of the description
text has been copied directly from the SNMP-TLS-TM-MIB, and modified
as necessary.
Copyright (c) 2012 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD
License set forth in Section 4.c of the IETF Trust's
Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and
// remove this note
// RFC Ed.: please update the date to the date of publication
revision "2012-02-13" {
description
"Initial version";
reference
"RFC XXXX: NETCONF over Transport Layer Security (TLS)";
}
typedef tls-fingerprint-type {
type binary {
length "0..255";
}
description
"A fingerprint value that can be used to uniquely reference
other data of potentially arbitrary length.
An tls-fingerprint-type value is composed of a 1-octet hashing
Badra Expires August 16, 2012 [Page 9]
Internet-Draft NETCONF over TLS February 2012
algorithm identifier followed by the fingerprint value. The
octet value encoded is taken from the IANA TLS HashAlgorithm
Registry (RFC 5246). The remaining octets are filled using the
results of the hashing algorithm.
This typedef allows for a zero-length (blank) tls-fingerprint-type
value for use in containers where the fingerprint value MAY be
optional. YANG definitions or implementations MAY refuse to
accept a zero-length value as appropriate.";
}
//
// Objects related to deriving NETCONF usernames from X.509 certificates.
//
leaf certificate-to-username-transform-count {
type yang:gauge32;
description
"A count of the number of certificate-to-username-transforms.";
config false;
}
leaf certificate-to-username-transform-last-changed {
type yang:date-and-time;
description
"The date and time when the certificate-to-username-transforms
was last modified through any means. The value 0 means the
certificate-to-username-transforms has not been modified since
the NETCONF server was started.";
config false;
}
container certificate-to-username-transforms {
config true;
description
"This container is used by a NETCONF server to map the NETCONF
client's presented X.509 certificate to a NETCONF username.
On an incoming TLS connection, the client's presented
certificate MUST either be validated based on an established
trust anchor, or it MUST directly match a fingerprint in this
container. This container does not provide any mechanisms for
configuring the trust anchors; the transfer of any needed
trusted certificates for path validation is expected to occur
through an out-of-band transfer.
Once the certificate has been found acceptable (either by path
validation or directly matching a fingerprint in this container),
this container is consulted to determine the appropriate
Badra Expires August 16, 2012 [Page 10]
Internet-Draft NETCONF over TLS February 2012
NETCONF username to associate with the remote connection. This
is done by considering each active list entry from this container
in prioritized order according to its index value.
Each list entry's certificate-fingerprint value determines
whether the list entry is a match for the incoming connection:
1) If the list entry's certificate-fingerprint value
matches that of the presented certificate, then consider
the list entry as a successful match.
2) If the list entry's certificate-fingerprint value
matches that of a locally held copy of a trusted CA
certificate, and that CA certificate was used to
validate the path to the presented certificate, then
consider the list entry as a successful match.
This feature lets the NETCONF server derive NETCONF
usernames from all certificates signed by the trusted
CA certificate. The NETCONF server will derive all
NETCONF usernames using the same derivation algorithm.
The NETCONF server requires only a single container
entry to configure this behavior.
Once a matching list entry has been found, the NETCONF server uses
the map-type value to determine how the NETCONF username
associated with the session should be determined. See the map-
type leaf's description for details on determining the NETCONF
username value. If it is impossible to determine a NETCONF
username from the list entry's data combined with the data
presented in the certificate, then additional list entries MUST be
searched looking for another potential match. If a resulting
NETCONF username mapped from a given list entry is not compatible
with the needed requirements of a NETCONF username, then it MUST
be considered an invalid match and additional list entries MUST be
searched looking for another potential match.
If no matching and valid list entry can be found, then the NETCONF
server MUST close the connection, and MUST NOT accept NETCONF
messages over it.
Non-consecutive values of index are acceptable and implementations
should continue to the next highest numbered list entry. It is
recommended that administrators skip index values to leave room
for the insertion of future list entries (for example, use values
of 10 and 20 when creating initial list entries).
Security administrators are encouraged to make use of certificates
Badra Expires August 16, 2012 [Page 11]
Internet-Draft NETCONF over TLS February 2012
with subjectAltName fields that can be used as NETCONF usernames
so that a single root CA certificate can allow all child
certificate's subjectAltName to map directly to a NETCONF
usernames via a 1:1 transformation. However, this container is
flexible to allow for situations where existing deployed
certificate infrastructures do not provide adequate subjectAltName
values for use as NETCONF usernames.";
// Certificates MAY also be mapped to NETCONF usernames using the
// CommonName portion of the Subject field. However, the usage
// of the CommonName field is deprecated and thus this usage is
// NOT RECOMMENDED. Direct mapping from each individual
// certificate fingerprint to a NETCONF username is also possible
// but requires one entry in the container per NETCONF username and
// requires more management operations to completely configure a
// device.";
list certificate-to-username-transform {
key "index";
description
"A single list entry that specifies a mapping for an incoming
TLS certificate to a NETCONF username.";
leaf index {
type uint32 {
range "1..4294967295";
}
description
"A unique, prioritized index for the given entry. Lower
numbers indicate a higher priority.";
}
leaf certificate-fingerprint {
type tls-fingerprint-type {
length "1..255";
}
description
"A cryptographic hash of a X.509 certificate. The results of
a successful matching fingerprint to either the trusted CA in
the certificate validation path or to the certificate itself
is dictated by the map-type leaf.";
}
leaf map-type {
type enumeration {
enum specified { value 1; }
enum rfc822Name { value 2; }
enum dnsName { value 3; }
Badra Expires August 16, 2012 [Page 12]
Internet-Draft NETCONF over TLS February 2012
enum ipAddress { value 4; }
enum rfc822Name-dnsName-ipAddress { value 5; }
enum rfc822Name-ipAddress-dnsName { value 6; }
enum dnsName-ipAddress-rfc822Name { value 7; }
enum dnsName-rfc822Name-ipAddress { value 8; }
enum ipAddress-dnsName-rfc822Name { value 9; }
enum ipAddress-rfc822Name-dnsName { value 10; }
}
description
"Specifies the algorithm for deriving a NETCONF username from
a certificate. If a mapping succeeds, then it will return a
NETCONF username.
If the resulting mapped value is not compatible with the needed
requirements of a NETCONF username, then future list entries MUST
be searched for additional NETCONF username matches to look for a
mapping that succeeds.
For each enumerated value listed above, the NETCONF server
derives the NETCONF from the presented client certificate
as described:
specified
Directly specifies the NETCONF username to be used for
this certificate. The value of the NETCONF username
to use is specified in the data leaf of the list. The
data leaf MUST contain a non-zero length value or the
mapping described in this list entry MUST be considered a
failure.
rfc822Name
Maps a subjectAltName's rfc822Name to a NETCONF username.
The local part of the rfc822Name is passed unaltered but
the host-part of the name MUST be passed in lowercase.
This mapping results in a 1:1 correspondence between
equivalent subjectAltName rfc822Name values and NETCONF
username values except that the host-part of the name
MUST be passed in lowercase.
Example rfc822Name Field: FooBar@Example.COM
is mapped to NETCONF username: FooBar@example.com.
dnsName
Maps a subjectAltName's dNSName to a NETCONF username after
Badra Expires August 16, 2012 [Page 13]
Internet-Draft NETCONF over TLS February 2012
first converting it to all lowercase (RFC 5280 does not
specify converting to lowercase so this involves an extra
step). This mapping results in a 1:1 correspondence between
subjectAltName dNSName values and the NETCONF username values.
reference: RFC 5280 - Internet X.509 Public Key Infrastructure
Certificate and Certificate Revocation
List (CRL) Profile.
ipAddress
Maps a subjectAltName's iPAddress to a NETCONF username by
transforming the binary encoded address as follows:
1) for IPv4, the value is converted into a
decimal-dotted quad address (e.g., '192.0.2.1').
2) for IPv6 addresses, the value is converted into a
32-character all lowercase hexadecimal string
without any colon separators.
This mapping results in a 1:1 correspondence between
subjectAltName iPAddress values and the NETCONF username
values.
rfc822Name-dnsName-ipAddress
rfc822Name-ipAddress-dnsName
dnsName-ipAddress-rfc822Name
dnsName-rfc822Name-ipAddress
ipAddress-dnsName-rfc822Name
ipAddress-rfc822Name-dnsName
For each of these enumerations, the NETCONF server derives the
NETCONF username in a similar manner. The NETCONF server
derives the NETCONF username from the subjectAltName fields
rfc822Name, dnsName, and ipAddress, as described in sections
above. However, each of these subjectAltName fields is
examined in the order specified by the enumeration name.
The first matching subjectAltName value found in the certificate
MUST be used when deriving the NETCONF username.
For example, the rfc822Name-dnsName-ipAddress enumeration
specifies the NETCONF server first examines the rfc822Name,
then examines the dnsName, then finally examines the ipAddress.
In contrast, the ipAddress-rfc822Name-dnsName enumeration
specifies the NETCONF server first examines the ipAddress
name, then examines the rfc822Name, then finally examines
the dnsName.
Badra Expires August 16, 2012 [Page 14]
Internet-Draft NETCONF over TLS February 2012
These mappings result in a 1:1 correspondence between
subjectAltName values and NETCONF username values. The
sub-mapping algorithms produced by these combined algorithms
cannot produce conflicting results between themselves.";
} // leaf map-type
leaf data {
type string {
length "1..max";
}
description
"Auxiliary data used as optional configuration information for
a given mapping specified by the map-type leaf. Only some
mapping systems will make use of this leaf. When the NETCONF
server derives the NETCONF username from the client's presented
certificate, the value in this leaf MUST be ignored for any
mapping type that does not require data present in this leaf.";
}
} // list certificate-to-username-transform
} // container certificate-to-username-transform
container psk-map {
list psk {
key psk-identity;
leaf psk-identity {
type string;
description
"The PSK identity encoded as a UTF-8 string.";
reference
"RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer
Security (TLS)";
}
leaf user-name {
type nacm:user-name-type;
mandatory true;
description
"The NETCONF username associated with this PSK identity.";
}
leaf valid-not-before {
type yang:date-and-time;
description
"This PSK identity is not valid before the given data
and time.";
}
Badra Expires August 16, 2012 [Page 15]
Internet-Draft NETCONF over TLS February 2012
leaf valid-not-after {
type yang:date-and-time;
description
"This PSK identity is not valid before the given data
and time.";
}
leaf key {
type binary;
nacm:default-deny-all;
description
"The key associated with the PSK identity";
}
}
} // container psk-identity-to-username-transform
}
4. Security Considerations
The security considerations described throughout [RFC5246] and
[RFC6241] apply here as well.
This document in its current version does not support third-party
authentication (e.g., backend Authentication, Authorization, and
Accounting (AAA) servers) due to the fact that TLS does not specify
this way of authentication and that NETCONF depends on the transport
protocol for the authentication service. If third-party
authentication is needed, BEEP or SSH transport can be used.
An attacker might be able to inject arbitrary NETCONF messages via
some application that does not carefully check exchanged messages.
When the :base:1.1 capability is not advertised by both peers, an
attacker might be able to deliberately insert the delimiter sequence
]]>]]> in a NETCONF message to create a DoS attack. If the :base:1.1
capability is not advertised by both peers, applications and NETCONF
APIs MUST ensure that the delimiter sequence ]]>]]> never appears in
NETCONF messages; otherwise, those messages can be dropped, garbled,
or misinterpreted. More specifically, if the delimiter sequence is
found in a NETCONF message by the sender side, a robust
implementation of this document SHOULD warn the user that illegal
characters have been discovered. If the delimiter sequence is found
in a NETCONF message by the receiver side (including any XML
attribute values, XML comments, or processing instructions), a robust
implementation of this document MUST silently discard the message
without further processing and then stop the NETCONF session.
Badra Expires August 16, 2012 [Page 16]
Internet-Draft NETCONF over TLS February 2012
Finally, this document does not introduce any new security
considerations compared to [RFC6242].
5. IANA Considerations
Based on the previous version of this document, RFC 5539, IANA has
assigned a TCP port number (6513) in the "Registered Port Numbers"
range with the name "netconf-tls". This port will be the default
port for NETCONF over TLS, as defined in this document.
Registration Contact: Mohamad Badra, mbadra@gmail.com.
Transport Protocol: TCP.
Port Number: 6513
Broadcast, Multicast or Anycast: No.
Port Name: netconf-tls.
Service Name: netconf.
Reference: RFC 5539
6. Acknowledgements
A significant amount of the text in Section 3 was lifted from
[RFC4642].
The author would like to acknowledge David Harrington, Miao Fuyou,
Eric Rescorla, Juergen Schoenwaelder, Simon Josefsson, Olivier
Coupelon, Alfred Hoenes, and the NETCONF mailing list members for
their comments on the document. The author also appreciates Bert
Wijnen, Mehmet Ersue, and Dan Romascanu for their efforts on issues
resolving discussion; and Charlie Kaufman, Pasi Eronen, and Tim Polk
for the thorough review of previous versions of this document.
Badra Expires August 16, 2012 [Page 17]
Internet-Draft NETCONF over TLS February 2012
7. Contributor's Address
Ibrahim Hajjeh
Ineovation
France
EMail: ibrahim.hajjeh@ineovation.fr
Alan Luchuk
SNMP Research, Inc.
3001 Kimberlin Heights Road
Knoxville, TN 37920-9716
EMail: luchuk@snmp.com
Juergen Schoenwaelder
Jacobs University Bremen
Campus Ring 1
28725 Bremen
Germany
EMail: j.schoenwaelder@jacobs-university.de
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4279] Eronen, P. and H. Tschofenig, "Pre-Shared Key Ciphersuites
for Transport Layer Security (TLS)", RFC 4279,
December 2005.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, June 2011.
[RFC6353] Hardaker, W., "Transport Layer Security (TLS) Transport
Model for the Simple Network Management Protocol (SNMP)",
Badra Expires August 16, 2012 [Page 18]
Internet-Draft NETCONF over TLS February 2012
RFC 6353, July 2011.
8.2. Informative References
[RFC4642] Murchison, K., Vinocur, J., and C. Newman, "Using
Transport Layer Security (TLS) with Network News Transfer
Protocol (NNTP)", RFC 4642, October 2006.
[RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event
Notifications", RFC 5277, July 2008.
[RFC5539] Badra, M., "NETCONF over Transport Layer Security (TLS)",
RFC 5539, May 2009.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)",
RFC 6241, June 2011.
Appendix A. Change Log (to be removed by RFC Editor before publication)
A.1. From -00 to -01
o Move RFC5539 to informative references and remove RFC4742.
o Shorten the YANG object names;
o Extend the YANG module to support configuration of PSK;
A.2. From RFC5539 to draft-badra-netconf-rfc5539bis-00
o Added text on how the generation of a NETCONF username is done.
o Added text on how does this document fulfill the requirements in
6241 for the format of the username.
o Removed unneeded wording about client/server, and changed use of
client/server, manager/agent to SSH client/server and NETCONF
client/server.
o Added text to Security Considerations about EOM issues.
o Added option for the chunked encoding described in RFC6242.
o Added 1.1 capability to enable the chunked encoding described in
RFC6242.
Badra Expires August 16, 2012 [Page 19]
Internet-Draft NETCONF over TLS February 2012
Author's Address
Mohamad Badra
Dhofar University
Email: mbadra@gmail.com
Badra Expires August 16, 2012 [Page 20]