Secure Shell Working Group J. Galbraith
Internet-Draft J. Van Dyke
Expires: September 18, 2005 B. McClure
VanDyke Software
J. Bright
Silicon Circus
March 17, 2005
Secure Shell Public-Key Subsystem
draft-ietf-secsh-publickey-subsystem-02.txt
Status of this Memo
This document is an Internet-Draft and is subject to all provisions
of Section 3 of RFC 3667. By submitting this Internet-Draft, each
author represents that any applicable patent or other IPR claims of
which he or she is aware have been or will be disclosed, and any of
which he or she become aware will be disclosed, in accordance with
RFC 3668.
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 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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 18, 2005.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
SECSH defines an authentication mechanism that is based on public
keys, but does not define any mechanism for key distribution. No
common key management solution exists in current implementations.
Galbraith, et al. Expires September 18, 2005 [Page 1]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
This document describes a protocol that can be used to configure
public keys in an implementation-independent fashion, allowing client
software to take on the burden of this configuration.
This protocol is intended to be used from the Secure Shell Connection
Protocol [4] as a subsystem, as described in the Section "Starting a
Shell or a Command". The subsystem name used with this protocol is
"publickey".
The public-key subsystem provides a server-independent mechanism for
clients to add public keys, remove public keys, and list the current
public keys known by the server. Rights to manage public keys are
specific and limited to the authenticated user.
A public key may also be associated with various restrictions,
including a mandatory command or subsystem.
Galbraith, et al. Expires September 18, 2005 [Page 2]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Public-Key Subsystem Overview . . . . . . . . . . . . . . . . 5
2.1 Opening the Public-Key Subsystem . . . . . . . . . . . . . 5
2.2 Requests . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Responses . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3.1 The Status Response . . . . . . . . . . . . . . . . . 6
3. Public-Key Subsystem Operations . . . . . . . . . . . . . . . 8
3.1 Version Packet . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Adding a public key . . . . . . . . . . . . . . . . . . . 8
3.3 Removing a public key . . . . . . . . . . . . . . . . . . 11
3.4 Listing public keys . . . . . . . . . . . . . . . . . . . 11
3.5 Listing server capabilities . . . . . . . . . . . . . . . 11
4. Security Considerations . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
5.1 Registrations . . . . . . . . . . . . . . . . . . . . . . 14
5.2 Names . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2.1 Conventions for Names . . . . . . . . . . . . . . . . 14
5.2.2 Future Assignments of Names . . . . . . . . . . . . . 14
5.3 Request names . . . . . . . . . . . . . . . . . . . . . . 15
5.4 Response names . . . . . . . . . . . . . . . . . . . . . . 15
5.5 Attribute names . . . . . . . . . . . . . . . . . . . . . 15
5.6 Status codes . . . . . . . . . . . . . . . . . . . . . . . 16
5.6.1 Conventions . . . . . . . . . . . . . . . . . . . . . 16
5.6.2 Initial Assignments . . . . . . . . . . . . . . . . . 16
5.6.3 Future Assignments . . . . . . . . . . . . . . . . . . 16
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1 Normative References . . . . . . . . . . . . . . . . . . . 17
6.2 Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . 19
Galbraith, et al. Expires September 18, 2005 [Page 3]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
1. Introduction
SECSH is a protocol for secure remote login and other secure network
services over an insecure network. SECSH defines an authentication
mechanism that is based on public keys, but does not define any
mechanism for key distribution. Common practice is to authenticate
once with password authentication and transfer the public key to the
server. However, to date no two implementations use the same
mechanism to configure a public key for use.
This document describes a subsystem that can be used to configure
public keys in an implementation-independent fashion. This approach
allows client software to take on the burden of this configuration.
The public-key subsystem protocol is designed for extreme simplicity
in implementation. It is not intended as a PKIX replacement.
The Secure Shell Public-Key subsystem has been designed to run on top
of the SECSH transport layer [2] and user authentication protocols
[3]. It provides a simple mechanism for the client to manage public
keys on the server.
This document should be read only after reading the SECSH
architecture [1] and SECSH connection [4] documents.
This protocol requires that the user be able to authenticate in some
fashion before it can be used. If password authentication is used,
servers SHOULD provide a configuration option to disable the use of
password authentication after the first public key is added.
Galbraith, et al. Expires September 18, 2005 [Page 4]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
2. Public-Key Subsystem Overview
The public-key subsystem provides a server-independent mechanism for
clients to add public keys, remove public keys, and list the current
public keys known by the server. The subsystem name is "publickey".
The public keys added, removed, and listed using this protocol are
specific and limited to those of the authenticated user.
The operations to add, remove and list the authenticated user's
public keys are performed as request packets sent to the server. The
server sends response packets that indicate success or failure as
well as provide specific response data.
The format of public-key blobs are detailed in the SSH Transport
Protocol document [2].
2.1 Opening the Public-Key Subsystem
The public-key subsystem is opened when the clients sends a
SSH_MSG_CHANNEL_REQUEST over an existing session.
The details of how a session is opened are described in the SSH
Connection Protocol document [4] in the section "Opening a Session".
To open the public-key subsystem, the client sends:
byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel
string "subsystem"
boolean want reply
string "publickey"
Client implementations SHOULD reject this request; it is normally
only sent by the client.
If want reply is TRUE, the server MUST respond with
SSH_MSG_CHANNEL_SUCCESS if the public-key subsystem was successfully
started or SSH_MSG_CHANNEL_FAILURE if the server failed to start or
does not support the public-key subsystem.
The server SHOULD respond with SSH_MSG_CHANNEL_FAILURE if the user
authenticated with a restricted public key that does not allow access
to the publickey subsystem.
It is RECOMMENDED that clients request and check the reply for this
request.
Galbraith, et al. Expires September 18, 2005 [Page 5]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
2.2 Requests
All public-key subsystem requests are sent in the following form:
uint32 length
string request-name
... request specific data follows
The length field describes the length of the request-name field and
the request-specific data, but not of the length field itself. The
client MUST receive acknowledgement of each request prior to sending
a new request.
All requests described in Section 3 are a description of the
'request-name' and 'data' portion of the packet.
2.3 Responses
All public-key subsystem responses are sent in the following form:
uint32 length
string response-name
... response specific data follows
2.3.1 The Status Response
A request is acknowledged by sending a status packet. If there is
data in response to the request, the status packet is sent after all
data has been sent.
string "status"
uint32 status code
string description [RFC-2279]
string language tag [RFC-1766]
A status message MUST be sent for any unrecognized packets and the
request SHOULD NOT close the subsystem.
2.3.1.1 Status Codes
The status code gives the status in a more machine-readable format
(suitable for localization), and can have the following values:
SSH_PUBLICKEY_SUCCESS 0
SSH_PUBLICKEY_ACCESS_DENIED 1
SSH_PUBLICKEY_STORAGE_EXCEEDED 2
SSH_PUBLICKEY_VERSION_NOT_SUPPORTED 3
Galbraith, et al. Expires September 18, 2005 [Page 6]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
SSH_PUBLICKEY_KEY_NOT_FOUND 4
SSH_PUBLICKEY_KEY_NOT_SUPPORTED 5
SSH_PUBLICKEY_KEY_ALREADY_PRESENT 6
SSH_PUBLICKEY_GENERAL_FAILURE 7
SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED 8
Galbraith, et al. Expires September 18, 2005 [Page 7]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
3. Public-Key Subsystem Operations
The public-key subsystem currently defines four operations: add,
remove, list, and listattributes.
3.1 Version Packet
Both sides MUST start by sending a version packet that indicates the
version of the protocol they are using.
string "version"
uint32 protocol-version-number
The version of the protocol described by this document is version 2.
Both sides send the highest version that they implement. The lower
of the version numbers is the version of the protocol to use. If
either side can't support the lower version, it should close the
subsystem and notify the other side by sending an
SSH_MSG_CHANNEL_CLOSE message. Before closing the subsystem, a
status message with the status SSH_PUBLICKEY_VERSION_NOT_SUPPORTED
SHOULD be sent.
Both sides MUST wait to receive this version before continuing. The
"version" packet MUST NOT be sent again after this initial exchange.
3.2 Adding a public key
If the client wishes to add a public key, the client sends:
string "add"
string public-key algorithm name
string public-key blob
boolean overwrite
uint32 attribute-count
string attrib-name
string attrib-value
bool mandatory
repeated attribute-count times
The server MUST attempt to store the public key for the user in the
appropriate location so the public key can be used for subsequent
public-key authentications. If the overwrite field is false and the
specified key already exists, the server MUST return
SSH_PUBLICKEY_KEY_ALREADY_PRESENT. If the server returns this, the
client SHOULD provide an option to the user to overwrite the key. If
the overwrite field is true and the specified key already exists but
cannot be overwritten, the server MUST return
Galbraith, et al. Expires September 18, 2005 [Page 8]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
SSH_PUBLICKEY_ACCESS_DENIED
Attribute names are defined following the same scheme laid out for
algorithm names in [1]. If the server does not implement a mandatory
attribute, it MUST fail the add. For the purposes of a mandatory
attribute, storage of the attribute is not sufficient, but requires
that the server understand and implement the intent of the attribute.
The following attributes are currently defined:
"comment"
The value of the comment attribute contains user-specified text about
the public key. The server SHOULD make every effort to preserve this
value and return it with the key during any subsequent list
operation. The server MUST NOT attempt to interpret or act upon the
content of the comment field in any way. The comment attribute must
be specified in UTF-8 format [6].
The comment field is useful so the user can identify the key without
resorting to comparing its fingerprint. This attribute SHOULD NOT be
mandatory.
"comment-language"
If this attribute is specified, it MUST immediately follow a
"comment" attribute and specifies the language for that attribute
[5]. The client MAY specify more than comment if it additionally
specifies a different language for each of those comments. The
server SHOULD attempt to store each comment, together with that
comment's lanuage attribute. This attribute SHOULD NOT be mandatory.
"command-override"
"command-override" specifies a command to be executed when this key
is in use. The command should be executed by the server when it
receives an "exec" or "shell" request from the client, in place of
the command or shell which would otherwise have been executed as a
result of that request. If the command string is empty, both "exec"
and "shell" requests should be denied. If no "command-override"
attribute is specified, all "exec" and "shell" requests should be
permitted (as long as they satisfy other security or authorisation
checks the server may perform). This attribute SHOULD be mandatory.
"subsystem"
"subsystem" specifies a comma-separated list of subsystems that may
be started (using a "subsystem" request) when this key is in use.
Galbraith, et al. Expires September 18, 2005 [Page 9]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
This attribute SHOULD be mandatory. If the value is empty, no
subsystems may be started.
"x11"
"x11" specifies that X11 forwarding may not be performed when this
key is in use. The attribute-value field SHOULD be empty for this
attribute. This attribute SHOULD be mandatory.
"shell"
"shell" specifies that session channel "shell" requests should be
denied when this key is in use. The attribute-value field SHOULD be
empty for this attribute. This attribute SHOULD be mandatory.
"exec"
"exec" specifies that session channel "exec" requests should be
denied when this key is in use. The attribute-value field SHOULD be
empty for this attribute. This attribute SHOULD be mandatory.
"agent"
"agent" specifies that session channel "auth-agent-req" requests
should be denied when this key is in use. The attribute-value field
SHOULD be empty for this attribute. This attribute SHOULD be
mandatory.
"env"
"env" specifies that session channel "env" requests should be denied
when this key is in use. The attribute-value field SHOULD be empty
for this attribute. This attribute SHOULD be mandatory.
"from"
"from" specifies a comma-separated list of hosts from which the key
may be used. If a host not in this list attempts to use this key for
authorisation purposes, the authorisation attempt MUST be denied.
The server SHOULD make a log entry regarding this.
"port-forward"
"port-forward" specifies that no "direct-tcpip" requests should be
accepted, except to those hosts specified in the comma-separated list
supplied as a value to this attribute. If the value of this
attribute is empty, all "direct-tcpip" requests should be refused
when using this key. This attribute SHOULD be mandatory.
Galbraith, et al. Expires September 18, 2005 [Page 10]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
"reverse-forward"
"reverse-forward" specifies that no "tcpip-forward" requests should
be accepted, accept for the port numbers in the comma-separated list
supplied as a value to this attribute. If the value of this
attribute is empty, all "tcpip-forward" requests should be refused
when using this key. This attribute SHOULD be mandatory.
In addition to the attributes specified by the client, the server MAY
provide a method for administrators to compulsorily enforce certain
attributes.
3.3 Removing a public key
If the client wishes to remove a public key, the client sends:
string "remove"
string public-key algorithm name
string public-key blob
The server MUST attempt to remove the public key for the user from
the appropriate location, so that the public key cannot be used for
subsequent authentications.
3.4 Listing public keys
If the client wishes to list the known public keys, the client sends:
string "list"
The server will respond with zero or more of the following responses:
string "publickey"
string public-key algorithm name
string public-key blob
uint32 attribute-count
string attrib-name
string attrib-value
repeated attribute-count times
Following the last "publickey" response, a status packet MUST be
sent.
An implementation MAY choose not to support this request.
3.5 Listing server capabilities
If the client wishes to know which key attributes the server
Galbraith, et al. Expires September 18, 2005 [Page 11]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
supports, it sends:
string "listattributes"
The server will respond with zero or more of the following responses:
string "attribute"
string attribute name
boolean compulsory
The "compulsory" field indicates whether this attribute will be
compulsorily applied to any added keys (irrespective of whether the
attribute has been specified by the client) due to administrative
settings on the server. If the server does not support
administrative settings of this nature, it MUST return false in the
compulsory field. An example of use of the "compulsory" attribute
would be a server with a configuration file specifying that the user
is not permitted shell access. Given this, the server would return
the "shell" attribute, with "compulsory" marked true. Whatever
attributes the user subsequently asked the server to apply to their
key, the server would also apply the "shell" attribute, rendering it
impossible for the user to use a shell.
Following the last "attribute" response, a status packet MUST be
sent.
An implementation MAY choose not to support this request.
Galbraith, et al. Expires September 18, 2005 [Page 12]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
4. Security Considerations
This protocol assumes that it is run over a secure channel and that
the endpoints of the channel have been authenticated. Thus, this
protocol assumes that it is externally protected from network-level
attacks.
This protocol provides a mechanism that allows client authentication
data to be uploaded and manipulated. It is the responsibility of the
server implementation to enforce any access controls that may be
required to limit the access allowed for any particular user (the
user being authenticated externally to this protocol, typically using
the SSH User Authentication Protocol [3]). In particular, it is
possible for users to overwrite an existing key on the server with
this protocol, whilst at the same time specifying fewer restrictions
for the new key than were previously present. Servers should take
care that when doing this, clients are not able to override presets
from the server's administrator.
This protocol requires the client to assume that the server will
correctly implement and observe attributes applied to keys.
Implementation errors in the server could cause clients to authorise
keys for access they were not intended to have, or to apply fewer
restrictions than were intended.
Galbraith, et al. Expires September 18, 2005 [Page 13]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
5. IANA Considerations
This section contains conventions used in naming the namespaces, the
initial state of the registry, and instructions for future
assignments.
5.1 Registrations
Consistent with section 7 of [1], this document makes the following
registration:
The subsystem name "publickey".
5.2 Names
In the following sections, the values for the name spaces are
textual. The conventions and instructions to the IANA for future
assignments are given in this section. The initial assignments are
given in their respective sections.
5.2.1 Conventions for Names
All names registered by the IANA in the following sections MUST be
printable US-ASCII strings, and MUST NOT contain the characters
at-sign ("@"), comma (","), or whitespace or control characters
(ASCII codes 32 or less). Names are case-sensitive, and MUST NOT be
longer than 64 characters.
A provision is made here for locally extensible names. The IANA will
not register, and will not control names with the at-sign in them.
Names with the at-sign in them will have the format of
"name@domainname" (without the double quotes) where the part
preceeding the at-sign is the name. The format of the part preceding
the at-sign is not specified, however these names MUST be printable
US-ASCII strings, and MUST NOT contain the comma character (","), or
whitespace, or control characters (ASCII codes 32 or less). The part
following the at-sign MUST be a valid, fully qualified internet
domain name [8] controlled by the person or organization defining the
name. Names are case-sensitive, and MUST NOT be longer than 64
characters. It is up to each domain how it manages its local
namespace. It has been noted that these names resemble STD 11 [7]
email addresses. This is purely coincidental and actually has
nothing to do with STD 11 [7]. An example of a locally defined name
is "ourcipher-cbc@example.com" (without the double quotes).
5.2.2 Future Assignments of Names
Requests for assignments of new Names MUST be done through the IETF
Galbraith, et al. Expires September 18, 2005 [Page 14]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
CONSENSUS method as described in [9].
5.3 Request names
The following table lists the initial assignments of Request names
Request Name
-------------
version
add
remove
list
listattributes
5.4 Response names
The following table lists the initial assignments of Response names
Response Name
--------------
version
status
publickey
attribute
5.5 Attribute names
Attributes are used to define properties or restrictions for public
keys. The following table lists the initial assignments of Response
names
Attribute Name
---------------
comment
comment-language
command-override
subsystem
x11
shell
exec
agent
env
from
port-forward
reverse-forward
Galbraith, et al. Expires September 18, 2005 [Page 15]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
5.6 Status codes
The status code is a byte value, describing the status of a request.
5.6.1 Conventions
Status responses have status codes in the range 0 to 255. These
numbers are allocated as follows. Of these, the range 192 to 255 is
reserved for use by local, private extensions.
5.6.2 Initial Assignments
The following table identifies the initial assignments of the status
code values.
Status code Value Reference
------------ ----- ---------
SSH_PUBLICKEY_SUCCESS 0
SSH_PUBLICKEY_ACCESS_DENIED 1
SSH_PUBLICKEY_STORAGE_EXCEEDED 2
SSH_PUBLICKEY_VERSION_NOT_SUPPORTED 3
SSH_PUBLICKEY_KEY_NOT_FOUND 4
SSH_PUBLICKEY_KEY_NOT_SUPPORTED 5
SSH_PUBLICKEY_KEY_ALREADY_PRESENT 6
SSH_PUBLICKEY_GENERAL_FAILURE 7
SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED 8
5.6.3 Future Assignments
Requests for assignments of new message numbers in the range of 0 to
191 MUST be done through the STANDARDS ACTION method as described in
[9].
The IANA will not control the message numbers range of 192 through
255. This range will be left for PRIVATE USE.
Galbraith, et al. Expires September 18, 2005 [Page 16]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
6. References
6.1 Normative References
[1] Lonvick, C., "SSH Protocol Architecture",
Internet-Draft draft-ietf-secsh-architecture-22, March 2005.
[2] Lonvick, C., "SSH Transport Layer Protocol",
Internet-Draft draft-ietf-secsh-transport-24, March 2005.
[3] Lonvick, C., "SSH Authentication Protocol",
Internet-Draft draft-ietf-secsh-userauth-27, March 2005.
[4] Lonvick, C., "SSH Connection Protocol",
Internet-Draft draft-ietf-secsh-connect-25, March 2005.
[5] Alvestrand, H., "Tags for the Identification of Languages",
RFC 1766, March 1995.
[6] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
RFC 2279, January 1998.
6.2 Informative References
[7] Crocker, D., "Standard for the format of ARPA Internet text
messages", STD 11, RFC 822, August 1982.
[8] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[9] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
Authors' Addresses
Joseph Galbraith
VanDyke Software
4848 Tramway Ridge Blvd
Suite 101
Albuquerque, NM 87111
US
Phone: +1 505 332 5700
Email: galb-list@vandyke.com
Galbraith, et al. Expires September 18, 2005 [Page 17]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
Jeff P. Van Dyke
VanDyke Software
4848 Tramway Ridge Blvd
Suite 101
Albuquerque, NM 87111
US
Phone: +1 505 332 5700
Email: jpv@vandyke.com
Brent McClure
VanDyke Software
4848 Tramway Ridge Blvd
Suite 101
Albuquerque, NM 87111
US
Phone: +1 505 332 5700
Email: bdm@vandyke.com
Jon Bright
Silicon Circus
24 Jubilee Road
Chichester, West Sussex PO19 7XB
UK
Phone: +49 172 524 0521
Email: jon@siliconcircus.com
Trademark notice
"ssh" is a registered trademark in the United States and/or other
countries.
Galbraith, et al. Expires September 18, 2005 [Page 18]
Internet-Draft Secure Shell Public-Key Subsystem March 2005
Intellectual Property Statement
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.
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 DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2005). 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.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
Galbraith, et al. Expires September 18, 2005 [Page 19]
