DHC Working Group Charles Monia
INTERNET DRAFT Josh Tseng
Expires: May 2005 Kevin Gibbons
Internet Draft McDATA
Corporation
Document: <draft-ietf-dhc-isnsoption-13.txt>
Category: Standards Track November 2004
The IPv4 DHCP Option for the Internet Storage Name Service
Status of this Memo
By submitting this Internet-Draft, I certify that any applicable
patent or other IPR claims of which I am aware have been disclosed,
or will be disclosed, and any of which I become aware will be
disclosed, in accordance with RFC 3668.
Internet-Drafts are working documents of the Internet Engineering
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Comments
Comments should be sent to the DHCP mailing list (dhcwg@ietf.org) or
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Monia, et-al Standards Track [Page 1]
DHCP Option Number for iSNS Revision 13 November 2004
Table of Contents
Status of this Memo...................................................1
Comments..............................................................1
Abstract..............................................................3
Conventions used in this document.....................................3
1. Introduction.......................................................3
2. iSNS Option for DHCP...............................................4
2.1 iSNS Functions Field..............................................5
2.2 Discovery Domain Access Field.....................................7
2.3 Administrative Flags Field........................................8
2.4 iSNS Server Security Bitmap.......................................9
3. Security Considerations...........................................10
4. IANA Considerations...............................................11
5. Normative References..............................................12
6. Non-Normative References..........................................12
7. Author's Addresses................................................13
8. Intellectual Property.............................................13
9. Full Copyright Statement..........................................13
10. Disclaimer of Validity...........................................13
11. Acknowledgement..................................................14
12. Expiration Notice................................................14
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Abstract
This document describes the DHCP option to allow Internet Storage
Name Service (iSNS) clients to automatically discover the location
of the iSNS server through the use of DHCP for IPv4. iSNS provides
discovery and management capabilities for Internet SCSI (iSCSI) and
Internet Fibre Channel Protocol (iFCP) storage devices in an
enterprise-scale IP storage network. iSNS provides intelligent
storage management services comparable to those found in Fibre
Channel networks, allowing a commodity IP network to function in a
similar capacity as a storage area network.
Conventions used in this document
iSNS refers to the Internet Storage Name Service framework
consisting of the storage network model and associated services.
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].
All frame formats are in big endian network byte order. RESERVED
fields SHOULD be set to zero.
This document uses the following terms:
"iSNS Client" - iSNS clients are processes resident in iSCSI and
iFCP devices that initiate transactions with the iSNS server using
the iSNS Protocol.
"iSNS Server" - The iSNS server responds to iSNS protocol query and
registration messages, and initiates asynchronous notification
messages. The iSNS server stores information registered by iSNS
clients.
"iSCSI (Internet SCSI)" - iSCSI is an encapsulation of SCSI for a
new generation of storage devices interconnected with TCP/IP.
"iFCP (Internet Fibre Channel Protocol)" - iFCP is a gateway-to-
gateway protocol designed to interconnect existing Fibre Channel
devices using TCP/IP. iFCP maps the Fibre Channel transport and
fabric services to TCP/IP.
1. Introduction
The Dynamic Host Configuration Protocol for IPv4 provides a
framework for passing configuration information to hosts. Its
usefulness extends to hosts and devices using the iSCSI and iFCP
protocols to connect to block level storage assets over a TCP/IP
network.
Monia, et-al Standards Track [Page 3]
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The iSNS Protocol provides a framework for automated discovery,
management, and configuration of iSCSI and iFCP devices on a TCP/IP
network. It provides functionality similar to that found on Fibre
Channel networks, except that iSNS works within the context of an IP
network. iSNS thereby provides the requisite storage intelligence
to IP networks that are standard on existing Fibre Channel networks.
Existing DHCP options cannot be used to find iSNS servers for the
following reasons:
a) iSNS functionality is distinctly different from other protocols
using DHCP options. Specifically, iSNS provides a significant
superset of capabilities compared to typical name resolution
protocols such as DNS. It is designed to support client devices
that allow themselves to be configured and managed from a
central iSNS server
b) iSNS requires a DHCP option format that provides more than the
location of the iSNS server. The DHCP option needs to specify
the subset of iSNS services that may be actively used by the
iSNS client.
The DHCP option number for iSNS is used by iSCSI and iFCP devices to
discover the location and role of the iSNS server. The DHCP option
number assigned for iSNS by IANA is <<TBD>>.
2. iSNS Option for DHCP
This option specifies the location of the primary and backup iSNS
servers and the iSNS services available to an iSNS client.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code = TBD | Length | iSNS Functions |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DD Access | Administrative FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| iSNS Server Security Bitmap |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| a1 | a2 | a3 | a4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| b1 | b2 | b3 | b4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . . . . |
| Additional Secondary iSNS Servers |
| . . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1 -- iSNS Server Option
The iSNS Option specifies a list of IP addresses used by iSNS
servers. The option contains the following parameters:
Monia, et-al Standards Track [Page 4]
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Length: the number of bytes that follow the Length field.
iSNS Functions: A bitmapped field defining the functions supported
by the iSNS servers. The format of this field is described
in section 2.1.
Discovery Domain Access: A bit field indicating the types of iSNS
clients that are allowed to modify Discovery Domains. The
field contents are described in section 2.2.
Administrative Flags field: Contains the administrative settings for
the iSNS servers discovered through the DHCP query. The
contents of this field are described in section 2.3.
iSNS Server Security Bitmap: Contains the iSNS server security
settings specified in section 2.4.
a1...a4: Depending on the setting of the Heartbeat bit in the
Administrative Flags field (see section 2.3), this field
contains either the IP address from which the iSNS heartbeat
originates (see [ISNS]) or the IP address of the primary
iSNS server.
b1...b4: Depending on the setting of Heartbeat bit in the
Administrative Flags field (see section 2.3), this field
contains either the IP address of the primary iSNS server or
a secondary iSNS server.
Additional Secondary iSNS Servers: Each set of four octets specifies
the IP address of a secondary iSNS server.
The Code field through IP address field a1...a4 MUST be present in
every response to the iSNS query, hence the Length field has a
minimum value of 14.
If the Heartbeat bit is set in the Administrative Flags field (see
section 2.3), then b1...b4 MUST also be present. In this case, the
minimum value of the Length field is 18.
The inclusion of Additional Secondary iSNS Servers in the response
MUST be indicated by increasing the Length field accordingly.
2.1 iSNS Functions Field
The iSNS Functions Field defines the iSNS server's operational role
(i.e., how the iSNS server is to be used). The iSNS server's role
can be as basic as providing simple discovery information, or as
significant as providing IKE/IPSec security policies and
certificates for the use of iSCSI and iFCP devices. The format of
the iSNS Functions field is shown in Figure 2:
Monia, et-al Standards Track [Page 5]
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0 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED |S|A|E|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2 -- iSNS Functions Field
Bit field Significance
--------- ------------
15 Function Fields Enabled
14 DD-Based Authorization
13 Security Policy Distribution
iSNS Functions Field definitions:
Function Fields This bit specifies the validity of the
Enabled: remaining iSNS Function fields. If set to
one, then the contents of all other iSNS
Function fields are valid. If set to zero,
then the contents of all other iSNS
Function fields MUST be ignored.
DD-based Indicates whether or not devices in a
Authorization: common Discovery Domain (DD) are implicitly
authorized to access one another. Although
Discovery Domains control the scope of
device discovery, they do not necessarily
indicate whether or not a domain member is
authorized to access discovered devices.
If this bit is set to one, then devices in
a common Discovery Domain are automatically
allowed access to each other (if
successfully authenticated). If this bit
is set to zero, then access authorization
is not implied by domain membership and
must be explicitly performed by each
device. In either case, devices not in a
common discovery domain are not allowed to
access each other.
Security Policy Indicates whether the iSNS client is to
Distribution: download and use the security policy
configuration stored in the iSNS server.
If set to one, then the policy is stored in
the iSNS server and must be used by the
iSNS client for its own security policy.
If set to zero, then the iSNS client must
obtain its security policy configuration by
other means.
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2.2 Discovery Domain Access Field
The format of the DD Access bit field is shown in Figure 3:
0 1 1 1 1 1 1
0 ... 9 0 1 2 3 4 5
+---+---+---+---+---+---+---+---+---+
| RESERVED | if| tf| is| ts| C | E |
+---+---+---+---+---+---+---+---+---+
Figure 3 -- Discovery Domain Access Field
Bit field Significance
--------- ------------
15 Enabled
14 Control Node
13 iSCSI Target
12 iSCSI Initiator
11 iFCP Target Port
10 iFCP Initiator Port
Discovery Domain Access Field Definitions:
Enabled: This bit specifies the validity of the
remaining DD Access bit fields. If this
bit is set to one, then the contents of
the remainder of the DD Access field are
valid. If this bit is set to zero, then
the contents of the remainder of this
field MUST be ignored.
Control Node: Specifies whether the iSNS server allows
Discovery Domains to be added, modified
or deleted by means of Control Nodes. If
set to one, then Control Nodes are
allowed to modify the Discovery Domain
configuration. If set to zero, then
Control Nodes are not allowed to modify
Discovery Domain configurations.
iSCSI Target, These bits determine whether the
iSCSI Initiator, respective registered iSNS client
iFCP Target Port, (determined by iSCSI Node Type or iFCP
iFCP Initiator Port Role) is allowed to add, delete, or
Port: modify Discovery Domains. If set to
one, then modification by the specified
client type is allowed. If set to zero,
then modification by the specified
client type is not allowed.
(A node may implement multiple node
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DHCP Option Number for iSNS Revision 13 November 2004
types.)
2.3 Administrative Flags Field
The format of the Administrative Flags bit field is shown in
Figure 4:
0 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED |D|M|H|E|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4 -- Administrative Flags
Bit Field Significance
--------- ------------
15 Enabled
14 Heartbeat
13 Management SCNs
12 Default Discovery Domain
Administrative Flags Field definitions:
Enabled: Specifies the validity of the remainder
of the Administrative Flags field. If
set to one, then the contents of the
remaining Administrative Flags are
valid. If set to zero, then the
remaining contents MUST be ignored,
indicating that iSNS administrative
settings are obtained through means
other than DHCP.
Heartbeat: Indicates whether the first IP address
is the multicast address to which the
iSNS heartbeat message is sent. If set
to one, then a1-a4 contains the
heartbeat multicast address and b1-b4
contains the IP address of the primary
iSNS server, followed by the IP
address(es) of any backup servers (see
Figure 1). If set to zero, then a1-a4
contains the IP address of the primary
iSNS server, followed by the IP
address(es) of any backup servers.
Management SCNs: Indicates whether control nodes are
authorized to register to receive
Management State Change Notifications
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(SCN's). Management SCN's are a special
class of State Change Notification whose
scope is the entire iSNS database. If
set to one, then control nodes are
authorized to register to receive
Management SCN's. If set to zero, then
control nodes are not authorized to
receive Management SCN's (although they
may receive normal SCN's).
Default Discovery Indicates whether a newly registered
Domain: device that is not explicitly placed
into a Discovery Domain (DD) and
Discovery Domain Set (DDS) should be
automatically placed into a default DD
and DDS. If set to one, then a default
DD shall contain all devices in the iSNS
database that have not been explicitly
placed into a DD by an iSNS client. If
set to zero, then devices not explicitly
placed into a DD are not members of any
DD.
2.4 iSNS Server Security Bitmap
The format of the iSNS server security Bitmap field is shown in
Figure 5. If valid, this field communicates to the DHCP client the
security settings that are required to communicate with the
indicated iSNS 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESERVED |T|X|P|A|M|S|E|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5 -- iSNS Server Security Bitmap
Bit Field Significance
--------- ----------------
31 Enabled
30 IKE/IPSec
29 Main Mode
28 Aggressive Mode
27 PFS
26 Transport Mode
25 Tunnel Mode
iSNS Server Security Bitmap definitions:
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Enabled This bit specifies the validity of the
remainder of the iSNS server security
bitmap. If set to one, then the contents
of the remainder of the field are valid.
If set to zero, then the contents of the
rest of the field are undefined and MUST
be ignored.
IKE/IPSec 1 = IKE/IPSec enabled; 0 = IKE/IPSec
disabled.
Main Mode 1 = Main Mode enabled; 0 = Main Mode
disabled.
Aggressive Mode 1 = Aggressive mode enabled; 0 =
Aggressive mode disabled.
PFS 1 = PFS enabled; 0 = PFS disabled.
Transport Mode 1 = Transport mode preferred; 0 = No
preference.
Tunnel Mode 1 = Tunnel mode preferred; 0 = No
preference.
If IKE/IPSec is disabled, this indicates that the Internet Key
Exchange (IKE) Protocol is not available to configure IPSec keys for
iSNS sessions to this iSNS server. It does not necessarily preclude
other key exchange methods (e.g., manual keying) from establishing
an IPSec security association for the iSNS session.
If IKE/IPsec is enabled, then for each of the bit pairs
<Main Mode, Aggressive Mode> and <Transport Mode, Tunnel Mode>,
one of the two bits MUST be set to 1 and the other bit
MUST be set to 0.
3. Security Considerations
The DHCP Authentication security option as specified in [RFC3118]
to protect the iSNS option may present a problem due to the limited
implementation and deployment of the DHCP authentication option.
The IPsec security mechanisms for iSNS itself are specified in
[iSNS] to provide confidentiality when sensitive information is
distributed via iSNS. See the Security Considerations section of
[iSNS] for details and specific requirements for implementation of
IPsec.
In addition, [iSNS] describes an authentication block that provides
message integrity for multicast or broadcast iSNS messages (i.e. for
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DHCP Option Number for iSNS Revision 13 November 2004
heartbeat/discovery messages only). See [RFC 3723] for further
discussion of security for these protocols.
If no sensitive information, as described in [iSNS], is being
distributed via iSNS, and an Entity is discovered via iSNS,
authentication and authorization are handled by the IP Storage
protocols whose endpoints are discovered via iSNS, specifically iFCP
[iFCP] and iSCSI [RFC 3720]. It is the responsibility of the
providers of these services to ensure that an inappropriately
advertised or discovered service does not compromise their security.
When no DHCP security is used, there is a risk of distribution of
false discovery information (e.g., via the iSNS DHCP option
identifying a false iSNS server that distributes the false
discovery information). The primary countermeasure for this risk
is authentication by the IP storage protocols discovered through
iSNS. When this risk is a significant concern, IPsec SAs SHOULD be
used (as specified in RFC 3723). For example, if an attacker uses
DHCP and iSNS to distribute discovery information that falsely
identifies an iSCSI endpoint, that endpoint will lack the
credentials necessary to successfully complete IKE authentication,
and hence will be prevented from falsely sending or receiving iSCSI
traffic. When this risk of false discovery information is a
significant concern and IPsec is implemented for iSNS, IPsec SAs
SHOULD also be used for iSNS traffic to prevent use of a false iSNS
server; this is more robust than relying only on the IP Storage
protocols to detect false discovery information.
When IPsec is implemented for iSNS, there is a risk of a denial of
service attack based on repeated use of false discovery information
that will cause initiation of IKE negotiation. The countermeasures
for this are administrative configuration of each iSNS Entity to
limit the peers that it is willing to communicate with (i.e., by IP
address range and/or DNS domain), and maintenance of a negative
authentication cache to avoid repeatedly contacting an iSNS Entity
that fails to authenticate. These three measures (i.e., IP address
range limits, DNS domain limits, negative authentication cache)
MUST be implemented for iSNS entities when this DHCP option is
used. An analogous argument applies to the IP storage protocols
that can be discovered via iSNS as discussed in RFC 3723.
In addition, use of the techniques described in [RFC2827] and
[RFC3833] may also be relevant to reduce denial of service attacks.
4. IANA Considerations
In accordance with the policy defined in [DHCP], IANA has assigned a
value of TBD for this option.
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There are no other IANA-assigned values defined by this
specification.
5. Normative References
[DHCP] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, Bucknell University, March 1997.
[iSNS] Tseng, J. et al., "iSNS - Internet Storage Name
Service", Internet draft (work in progress), draft-ietf-
ips-isns-12.txt, August 2002
[RFC2026] Bradner, S., "The Internet Standards Process --
Revision 3", BCP 9, RFC 2026, October 1996
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997
[RFC3118] Arbaugh, W., Droms, R., "Authentication for DHCP
Messages", RFC 3118, June 2001
[RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78,
RFC 3667, February 2004
[RFC3668] Bradner, S., "Intellectual Property Rights in IETF
Technology", BCP 79, RFC 3668, February 2004
[RFC3720] Satran, J., et al., "Internet Small Computer Systems
Interface (iSCSI)", RFC 3720, April 2004
[RFC3723] Aboba, B., et al., "Securing Block Storage Protocols
over IP", RFC 3723, April 2004
6. Non-Normative References
[iFCP] Monia, C., et al., "iFCP - A Protocol for Internet Fibre
Channel Storage Networking", Internet draft (work in
progress), draft-ietf-ips-ifcp-13.txt, May 2002
[RFC2827] Ferguson, P., et al., "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP
Source Address Spoofing", BCP 38, RFC 2827, May 2000
[RFC3833] Atkins, D., et al., "Threat Analysis of the Domain
Name System (DNS)", RFC 3833, August 2004
Monia, et-al Standards Track [Page 12]
7. Author's Addresses
Kevin Gibbons,
Charles Monia,
Josh Tseng
McDATA Corporation
3850 North First Street
San Jose, CA 95134-1702
Phone: (408) 519-3700
Email: charles.monia@mcdata.com
joshtseng@yahoo.com
kevin.gibbons@mcdata.com
8. Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in this
document or the extent to which any license under such rights might or
might not be available; nor does it represent that it has made any
independent effort to identify any such rights. Information on the
procedures with respect to rights in RFC documents can be found in BCP 78
and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any assurances
of licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such proprietary
rights by implementers or users of this specification can be obtained
from the IETF on-line IPR repository at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary rights
that may cover technology that may be required to implement this
standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
9. Full Copyright Statement
Copyright (C) The Inter
net Society July 2004. This document is subject to
the rights, licenses and restrictions contained in BCP 78, and except as
set forth therein, the authors retain all their rights.
10. Disclaimer of Validity
This document and the information contained herein are provided on an "AS
IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS
SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL
Monia, et-al Standards Track [Page 13]
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NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.
Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months and
may be upated, 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 a "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
11. Acknowledgement
Funding for the RFC Editor function is currently provided by the Internet
Society.
12. Expiration Notice
This Internet-Draft expires in May 2005.
Monia, et-al Standards Track [Page 14]
