draft-ietf-secsh-publickey-subsystem-02.txt   draft-ietf-secsh-publickey-subsystem-03.txt 
Secure Shell Working Group J. Galbraith Secure Shell Working Group J. Galbraith
Internet-Draft J. Van Dyke Internet-Draft J. Van Dyke
Expires: September 18, 2005 B. McClure Expires: February 25, 2006 B. McClure
VanDyke Software VanDyke Software
J. Bright J. Bright
Silicon Circus Silicon Circus
March 17, 2005 August 24, 2005
Secure Shell Public-Key Subsystem Secure Shell Public-Key Subsystem
draft-ietf-secsh-publickey-subsystem-02.txt draft-ietf-secsh-publickey-subsystem-03.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
SECSH defines an authentication mechanism that is based on public SECSH defines an authentication mechanism that is based on public
keys, but does not define any mechanism for key distribution. No keys, but does not define any mechanism for key distribution. No
common key management solution exists in current implementations. common key management solution exists in current implementations.
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The public-key subsystem provides a server-independent mechanism for The public-key subsystem provides a server-independent mechanism for
clients to add public keys, remove public keys, and list the current clients to add public keys, remove public keys, and list the current
public keys known by the server. Rights to manage public keys are public keys known by the server. Rights to manage public keys are
specific and limited to the authenticated user. specific and limited to the authenticated user.
A public key may also be associated with various restrictions, A public key may also be associated with various restrictions,
including a mandatory command or subsystem. including a mandatory command or subsystem.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Public-Key Subsystem Overview . . . . . . . . . . . . . . . . 5 2. Public-Key Subsystem Overview . . . . . . . . . . . . . . . . 4
2.1 Opening the Public-Key Subsystem . . . . . . . . . . . . . 5 2.1. Opening the Public-Key Subsystem . . . . . . . . . . . . . 4
2.2 Requests . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2. Requests and Responses . . . . . . . . . . . . . . . . . . 5
2.3 Responses . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3. The Status Message . . . . . . . . . . . . . . . . . . . . 5
2.3.1 The Status Response . . . . . . . . . . . . . . . . . 6 2.3.1. Status Codes . . . . . . . . . . . . . . . . . . . . . 5
3. Public-Key Subsystem Operations . . . . . . . . . . . . . . . 8 2.4. The Version Packet . . . . . . . . . . . . . . . . . . . . 6
3.1 Version Packet . . . . . . . . . . . . . . . . . . . . . . 8 3. Public-Key Subsystem Operations . . . . . . . . . . . . . . . 7
3.2 Adding a public key . . . . . . . . . . . . . . . . . . . 8 3.1. Adding a public key . . . . . . . . . . . . . . . . . . . 7
3.3 Removing a public key . . . . . . . . . . . . . . . . . . 11 3.2. Removing a public key . . . . . . . . . . . . . . . . . . 10
3.4 Listing public keys . . . . . . . . . . . . . . . . . . . 11 3.3. Listing public keys . . . . . . . . . . . . . . . . . . . 10
3.5 Listing server capabilities . . . . . . . . . . . . . . . 11 3.4. Listing server capabilities . . . . . . . . . . . . . . . 10
4. Security Considerations . . . . . . . . . . . . . . . . . . . 13 4. Security Considerations . . . . . . . . . . . . . . . . . . . 12
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
5.1 Registrations . . . . . . . . . . . . . . . . . . . . . . 14 5.1. Registrations . . . . . . . . . . . . . . . . . . . . . . 13
5.2 Names . . . . . . . . . . . . . . . . . . . . . . . . . . 14 5.2. Names . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2.1 Conventions for Names . . . . . . . . . . . . . . . . 14 5.2.1. Conventions for Names . . . . . . . . . . . . . . . . 13
5.2.2 Future Assignments of Names . . . . . . . . . . . . . 14 5.2.2. Future Assignments of Names . . . . . . . . . . . . . 13
5.3 Request names . . . . . . . . . . . . . . . . . . . . . . 15 5.3. Request names . . . . . . . . . . . . . . . . . . . . . . 14
5.4 Response names . . . . . . . . . . . . . . . . . . . . . . 15 5.4. Response names . . . . . . . . . . . . . . . . . . . . . . 14
5.5 Attribute names . . . . . . . . . . . . . . . . . . . . . 15 5.5. Attribute names . . . . . . . . . . . . . . . . . . . . . 14
5.6 Status codes . . . . . . . . . . . . . . . . . . . . . . . 16 5.6. Status codes . . . . . . . . . . . . . . . . . . . . . . . 15
5.6.1 Conventions . . . . . . . . . . . . . . . . . . . . . 16 5.6.1. Conventions . . . . . . . . . . . . . . . . . . . . . 15
5.6.2 Initial Assignments . . . . . . . . . . . . . . . . . 16 5.6.2. Initial Assignments . . . . . . . . . . . . . . . . . 15
5.6.3 Future Assignments . . . . . . . . . . . . . . . . . . 16 5.6.3. Future Assignments . . . . . . . . . . . . . . . . . . 15
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1 Normative References . . . . . . . . . . . . . . . . . . . 17 6.1. Normative References . . . . . . . . . . . . . . . . . . . 16
6.2 Informative References . . . . . . . . . . . . . . . . . . 17 6.2. Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 17 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
Intellectual Property and Copyright Statements . . . . . . . . 19 Intellectual Property and Copyright Statements . . . . . . . . . . 18
1. Introduction 1. Introduction
SECSH is a protocol for secure remote login and other secure network SECSH is a protocol for secure remote login and other secure network
services over an insecure network. SECSH defines an authentication services over an insecure network. SECSH defines an authentication
mechanism that is based on public keys, but does not define any mechanism that is based on public keys, but does not define any
mechanism for key distribution. Common practice is to authenticate mechanism for key distribution. Common practice is to authenticate
once with password authentication and transfer the public key to the once with password authentication and transfer the public key to the
server. However, to date no two implementations use the same server. However, to date no two implementations use the same
mechanism to configure a public key for use. mechanism to configure a public key for use.
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specific and limited to those of the authenticated user. specific and limited to those of the authenticated user.
The operations to add, remove and list the authenticated user's The operations to add, remove and list the authenticated user's
public keys are performed as request packets sent to the server. The public keys are performed as request packets sent to the server. The
server sends response packets that indicate success or failure as server sends response packets that indicate success or failure as
well as provide specific response data. well as provide specific response data.
The format of public-key blobs are detailed in the SSH Transport The format of public-key blobs are detailed in the SSH Transport
Protocol document [2]. Protocol document [2].
2.1 Opening the Public-Key Subsystem 2.1. Opening the Public-Key Subsystem
The public-key subsystem is opened when the clients sends a The public-key subsystem is started by a client sending an
SSH_MSG_CHANNEL_REQUEST over an existing session. SSH_MSG_CHANNEL_REQUEST over an existing session's channel.
The details of how a session is opened are described in the SSH The details of how a session is opened are described in the SSH
Connection Protocol document [4] in the section "Opening a Session". Connection Protocol document [4] in the section "Opening a Session".
To open the public-key subsystem, the client sends: To open the public-key subsystem, the client sends:
byte SSH_MSG_CHANNEL_REQUEST byte SSH_MSG_CHANNEL_REQUEST
uint32 recipient channel uint32 recipient channel
string "subsystem" string "subsystem"
boolean want reply boolean want reply
string "publickey" string "publickey"
Client implementations SHOULD reject this request; it is normally Client implementations SHOULD reject this request; it is normally
only sent by the client. sent only by the client.
If want reply is TRUE, the server MUST respond with If want reply is TRUE, the server MUST respond with
SSH_MSG_CHANNEL_SUCCESS if the public-key subsystem was successfully SSH_MSG_CHANNEL_SUCCESS if the public-key subsystem was successfully
started or SSH_MSG_CHANNEL_FAILURE if the server failed to start or started or SSH_MSG_CHANNEL_FAILURE if the server failed to start or
does not support the public-key subsystem. does not support the public-key subsystem.
The server SHOULD respond with SSH_MSG_CHANNEL_FAILURE if the user The server SHOULD respond with SSH_MSG_CHANNEL_FAILURE if the user is
authenticated with a restricted public key that does not allow access not allowed access to the publickey subsystem (for example because
to the publickey subsystem. the user authenticated with a restricted public key).
It is RECOMMENDED that clients request and check the reply for this It is RECOMMENDED that clients request and check the reply for this
request. request.
2.2 Requests 2.2. Requests and Responses
All public-key subsystem requests are sent in the following form: All public-key subsystem requests and responses are sent in the
following form:
uint32 length uint32 length
string request-name string name
... request specific data follows ... request/response 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: The length field describes the length of the name field and the
request/response-specific data, but does not include the length of
the length field itself. The client MUST receive acknowledgement of
each request prior to sending a new request.
uint32 length The version packet, as well as all requests and responses described
string response-name in Section 3 are a description of the 'name' field and the data part
... response specific data follows of the packet.
2.3.1 The Status Response 2.3. The Status Message
A request is acknowledged by sending a status packet. If there is 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 in response to the request, the status packet is sent after all
data has been sent. data has been sent.
string "status" string "status"
uint32 status code uint32 status code
string description [RFC-2279] string description [RFC-2279]
string language tag [RFC-1766] string language tag [RFC-1766]
A status message MUST be sent for any unrecognized packets and the A status message MUST be sent for any unrecognized packets and the
request SHOULD NOT close the subsystem. request SHOULD NOT close the subsystem.
2.3.1.1 Status Codes 2.3.1. Status Codes
The status code gives the status in a more machine-readable format The status code gives the status in a more machine-readable format
(suitable for localization), and can have the following values: (suitable for localization), and can have the following values:
SSH_PUBLICKEY_SUCCESS 0 SSH_PUBLICKEY_SUCCESS 0
SSH_PUBLICKEY_ACCESS_DENIED 1 SSH_PUBLICKEY_ACCESS_DENIED 1
SSH_PUBLICKEY_STORAGE_EXCEEDED 2 SSH_PUBLICKEY_STORAGE_EXCEEDED 2
SSH_PUBLICKEY_VERSION_NOT_SUPPORTED 3 SSH_PUBLICKEY_VERSION_NOT_SUPPORTED 3
SSH_PUBLICKEY_KEY_NOT_FOUND 4 SSH_PUBLICKEY_KEY_NOT_FOUND 4
SSH_PUBLICKEY_KEY_NOT_SUPPORTED 5 SSH_PUBLICKEY_KEY_NOT_SUPPORTED 5
SSH_PUBLICKEY_KEY_ALREADY_PRESENT 6 SSH_PUBLICKEY_KEY_ALREADY_PRESENT 6
SSH_PUBLICKEY_GENERAL_FAILURE 7 SSH_PUBLICKEY_GENERAL_FAILURE 7
SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED 8 SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED 8
SSH_PUBLICKEY_ATTRIBUTE_NOT_SUPPORTED 9
If a request completed successfully, the server MUST send the status
code SSH_PUBLICKEY_SUCCESS. The meaning of the failure codes is as
implied by their names.
3. Public-Key Subsystem Operations 2.4. The Version Packet
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 Both sides MUST start by sending a version packet that indicates the
version of the protocol they are using. version of the protocol they are using.
string "version" string "version"
uint32 protocol-version-number uint32 protocol-version-number
The version of the protocol described by this document is version 2. The version of the protocol described by this document is version 2.
Both sides send the highest version that they implement. The lower Both sides send the highest version that they implement. The lower
of the version numbers is the version of the protocol to use. If 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 either side can't support the lower version, it should close the
subsystem and notify the other side by sending an subsystem and notify the other side by sending an
SSH_MSG_CHANNEL_CLOSE message. Before closing the subsystem, a SSH_MSG_CHANNEL_CLOSE message. Before closing the subsystem, a
status message with the status SSH_PUBLICKEY_VERSION_NOT_SUPPORTED status message with the status SSH_PUBLICKEY_VERSION_NOT_SUPPORTED
SHOULD be sent. SHOULD be sent. Note that normally, status messages are only sent by
the server in response to requests from the client. This is the only
occasion on which the client sends a status message.
Both sides MUST wait to receive this version before continuing. The Both sides MUST wait to receive this version before continuing. The
"version" packet MUST NOT be sent again after this initial exchange. "version" packet MUST NOT be sent again after this initial exchange.
The SSH_PUBLICKEY_VERSION_NOT_SUPPORTED status code must not be sent
in response to any other request.
3.2 Adding a public key 3. Public-Key Subsystem Operations
The public-key subsystem currently defines four operations: add,
remove, list, and listattributes.
3.1. Adding a public key
If the client wishes to add a public key, the client sends: If the client wishes to add a public key, the client sends:
string "add" string "add"
string public-key algorithm name string public-key algorithm name
string public-key blob string public-key blob
boolean overwrite boolean overwrite
uint32 attribute-count uint32 attribute-count
string attrib-name string attrib-name
string attrib-value string attrib-value
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public-key authentications. If the overwrite field is false and the public-key authentications. If the overwrite field is false and the
specified key already exists, the server MUST return specified key already exists, the server MUST return
SSH_PUBLICKEY_KEY_ALREADY_PRESENT. If the server returns this, the SSH_PUBLICKEY_KEY_ALREADY_PRESENT. If the server returns this, the
client SHOULD provide an option to the user to overwrite the key. If 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 the overwrite field is true and the specified key already exists but
cannot be overwritten, the server MUST return cannot be overwritten, the server MUST return
SSH_PUBLICKEY_ACCESS_DENIED SSH_PUBLICKEY_ACCESS_DENIED
Attribute names are defined following the same scheme laid out for Attribute names are defined following the same scheme laid out for
algorithm names in [1]. If the server does not implement a mandatory 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, it MUST fail the add, with the status code
attribute, storage of the attribute is not sufficient, but requires SSH_PUBLICKEY_ATTRIBUTE_NOT_SUPPORTED. For the purposes of a
that the server understand and implement the intent of the attribute. 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: The following attributes are currently defined:
"comment" "comment"
The value of the comment attribute contains user-specified text about The value of the comment attribute contains user-specified text about
the public key. The server SHOULD make every effort to preserve this the public key. The server SHOULD make every effort to preserve this
value and return it with the key during any subsequent list value and return it with the key during any subsequent list
operation. The server MUST NOT attempt to interpret or act upon the operation. The server MUST NOT attempt to interpret or act upon the
content of the comment field in any way. The comment attribute must content of the comment field in any way. The comment attribute must
be specified in UTF-8 format [6]. be specified in UTF-8 format [6].
The comment field is useful so the user can identify the key without The comment field is useful so the user can identify the key without
resorting to comparing its fingerprint. This attribute SHOULD NOT be resorting to comparing its fingerprint. This attribute SHOULD NOT be
mandatory. mandatory.
"comment-language" "comment-language"
If this attribute is specified, it MUST immediately follow a If this attribute is specified, it MUST immediately follow a
"comment" attribute and specifies the language for that attribute "comment" attribute and specifies the language for that attribute
[5]. The client MAY specify more than comment if it additionally [5]. The client MAY specify more than one comment if it additionally
specifies a different language for each of those comments. The specifies a different language for each of those comments. The
server SHOULD attempt to store each comment, together with that server SHOULD attempt to store each comment, together with that
comment's lanuage attribute. This attribute SHOULD NOT be mandatory. comment's lanuage attribute. This attribute SHOULD NOT be mandatory.
"command-override" "command-override"
"command-override" specifies a command to be executed when this key "command-override" specifies a command to be executed when this key
is in use. The command should be executed by the server when it 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 receives an "exec" or "shell" request from the client, in place of
the command or shell which would otherwise have been executed as a the command or shell which would otherwise have been executed as a
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result of that request. If the command string is empty, both "exec" result of that request. If the command string is empty, both "exec"
and "shell" requests should be denied. If no "command-override" and "shell" requests should be denied. If no "command-override"
attribute is specified, all "exec" and "shell" requests should be attribute is specified, all "exec" and "shell" requests should be
permitted (as long as they satisfy other security or authorisation permitted (as long as they satisfy other security or authorisation
checks the server may perform). This attribute SHOULD be mandatory. checks the server may perform). This attribute SHOULD be mandatory.
"subsystem" "subsystem"
"subsystem" specifies a comma-separated list of subsystems that may "subsystem" specifies a comma-separated list of subsystems that may
be started (using a "subsystem" request) when this key is in use. be started (using a "subsystem" request) when this key is in use.
This attribute SHOULD be mandatory. If the value is empty, no This attribute SHOULD be mandatory. If the value is empty, no
subsystems may be started. subsystems may be started. If the "subsystem" attribute is not
specified, no restrictions are placed on which subsystems may be
started when authenticated using this key.
"x11" "x11"
"x11" specifies that X11 forwarding may not be performed when this "x11" specifies that X11 forwarding may not be performed when this
key is in use. The attribute-value field SHOULD be empty for this key is in use. The attribute-value field SHOULD be empty for this
attribute. This attribute SHOULD be mandatory. attribute. This attribute SHOULD be mandatory.
"shell" "shell"
"shell" specifies that session channel "shell" requests should be "shell" specifies that session channel "shell" requests should be
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"env" specifies that session channel "env" requests should be denied "env" specifies that session channel "env" requests should be denied
when this key is in use. The attribute-value field SHOULD be empty when this key is in use. The attribute-value field SHOULD be empty
for this attribute. This attribute SHOULD be mandatory. for this attribute. This attribute SHOULD be mandatory.
"from" "from"
"from" specifies a comma-separated list of hosts from which the key "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 may be used. If a host not in this list attempts to use this key for
authorisation purposes, the authorisation attempt MUST be denied. authorisation purposes, the authorisation attempt MUST be denied.
The server SHOULD make a log entry regarding this. The server SHOULD make a log entry regarding this. The server MAY
provide a method for administrators to disallow the appearance of a
host in this list.
"port-forward" "port-forward"
"port-forward" specifies that no "direct-tcpip" requests should be "port-forward" specifies that no "direct-tcpip" requests should be
accepted, except to those hosts specified in the comma-separated list accepted, except to those hosts specified in the comma-separated list
supplied as a value to this attribute. If the value of this supplied as a value to this attribute. If the value of this
attribute is empty, all "direct-tcpip" requests should be refused attribute is empty, all "direct-tcpip" requests should be refused
when using this key. This attribute SHOULD be mandatory. when using this key. This attribute SHOULD be mandatory.
"reverse-forward" "reverse-forward"
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"reverse-forward" specifies that no "tcpip-forward" requests should "reverse-forward" specifies that no "tcpip-forward" requests should
be accepted, accept for the port numbers in the comma-separated list be accepted, accept for the port numbers in the comma-separated list
supplied as a value to this attribute. If the value of this supplied as a value to this attribute. If the value of this
attribute is empty, all "tcpip-forward" requests should be refused attribute is empty, all "tcpip-forward" requests should be refused
when using this key. This attribute SHOULD be mandatory. when using this key. This attribute SHOULD be mandatory.
In addition to the attributes specified by the client, the server MAY In addition to the attributes specified by the client, the server MAY
provide a method for administrators to compulsorily enforce certain provide a method for administrators to compulsorily enforce certain
attributes. attributes.
3.3 Removing a public key 3.2. Removing a public key
If the client wishes to remove a public key, the client sends: If the client wishes to remove a public key, the client sends:
string "remove" string "remove"
string public-key algorithm name string public-key algorithm name
string public-key blob string public-key blob
The server MUST attempt to remove the public key for the user from 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 the appropriate location, so that the public key cannot be used for
subsequent authentications. subsequent authentications.
3.4 Listing public keys 3.3. Listing public keys
If the client wishes to list the known public keys, the client sends: If the client wishes to list the known public keys, the client sends:
string "list" string "list"
The server will respond with zero or more of the following responses: The server will respond with zero or more of the following responses:
string "publickey" string "publickey"
string public-key algorithm name string public-key algorithm name
string public-key blob string public-key blob
uint32 attribute-count uint32 attribute-count
string attrib-name string attrib-name
string attrib-value string attrib-value
repeated attribute-count times repeated attribute-count times
Following the last "publickey" response, a status packet MUST be Following the last "publickey" response, a status packet MUST be
sent. sent.
An implementation MAY choose not to support this request. An implementation MAY choose not to support this request.
3.5 Listing server capabilities 3.4. Listing server capabilities
If the client wishes to know which key attributes the server If the client wishes to know which key attributes the server
supports, it sends: supports, it sends:
string "listattributes" string "listattributes"
The server will respond with zero or more of the following responses: The server will respond with zero or more of the following responses:
string "attribute" string "attribute"
string attribute name string attribute name
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Implementation errors in the server could cause clients to authorise Implementation errors in the server could cause clients to authorise
keys for access they were not intended to have, or to apply fewer keys for access they were not intended to have, or to apply fewer
restrictions than were intended. restrictions than were intended.
5. IANA Considerations 5. IANA Considerations
This section contains conventions used in naming the namespaces, the This section contains conventions used in naming the namespaces, the
initial state of the registry, and instructions for future initial state of the registry, and instructions for future
assignments. assignments.
5.1 Registrations 5.1. Registrations
Consistent with section 7 of [1], this document makes the following Consistent with section 7 of [1], this document makes the following
registration: registration:
The subsystem name "publickey". The subsystem name "publickey".
5.2 Names 5.2. Names
In the following sections, the values for the name spaces are In the following sections, the values for the name spaces are
textual. The conventions and instructions to the IANA for future textual. The conventions and instructions to the IANA for future
assignments are given in this section. The initial assignments are assignments are given in this section. The initial assignments are
given in their respective sections. given in their respective sections.
5.2.1 Conventions for Names 5.2.1. Conventions for Names
All names registered by the IANA in the following sections MUST be All names registered by the IANA in the following sections MUST be
printable US-ASCII strings, and MUST NOT contain the characters printable US-ASCII strings, and MUST NOT contain the characters at-
at-sign ("@"), comma (","), or whitespace or control characters sign ("@"), comma (","), or whitespace or control characters (ASCII
(ASCII codes 32 or less). Names are case-sensitive, and MUST NOT be codes 32 or less). Names are case-sensitive, and MUST NOT be longer
longer than 64 characters. than 64 characters.
A provision is made here for locally extensible names. The IANA will 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. 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 Names with the at-sign in them will have the format of
"name@domainname" (without the double quotes) where the part "name@domainname" (without the double quotes) where the part
preceeding the at-sign is the name. The format of the part preceding 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 the at-sign is not specified, however these names MUST be printable
US-ASCII strings, and MUST NOT contain the comma character (","), or US-ASCII strings, and MUST NOT contain the comma character (","), or
whitespace, or control characters (ASCII codes 32 or less). The part whitespace, or control characters (ASCII codes 32 or less). The part
following the at-sign MUST be a valid, fully qualified internet following the at-sign MUST be a valid, fully qualified internet
domain name [8] controlled by the person or organization defining the domain name [8] controlled by the person or organization defining the
name. Names are case-sensitive, and MUST NOT be longer than 64 name. Names are case-sensitive, and MUST NOT be longer than 64
characters. It is up to each domain how it manages its local characters. It is up to each domain how it manages its local
namespace. It has been noted that these names resemble STD 11 [7] namespace. It has been noted that these names resemble STD 11 [7]
email addresses. This is purely coincidental and actually has email addresses. This is purely coincidental and actually has
nothing to do with STD 11 [7]. An example of a locally defined name nothing to do with STD 11 [7]. An example of a locally defined name
is "ourcipher-cbc@example.com" (without the double quotes). is "ourcipher-cbc@example.com" (without the double quotes).
5.2.2 Future Assignments of Names 5.2.2. Future Assignments of Names
Requests for assignments of new Names MUST be done through the IETF Requests for assignments of new Names MUST be done through the IETF
CONSENSUS method as described in [9]. CONSENSUS method as described in [9].
5.3 Request names 5.3. Request names
The following table lists the initial assignments of Request names The following table lists the initial assignments of Request names
Request Name Request Name
------------- -------------
version version
add add
remove remove
list list
listattributes listattributes
5.4 Response names 5.4. Response names
The following table lists the initial assignments of Response names The following table lists the initial assignments of Response names
Response Name Response Name
-------------- --------------
version version
status status
publickey publickey
attribute attribute
5.5 Attribute names 5.5. Attribute names
Attributes are used to define properties or restrictions for public Attributes are used to define properties or restrictions for public
keys. The following table lists the initial assignments of Response keys. The following table lists the initial assignments of Response
names names
Attribute Name Attribute Name
--------------- ---------------
comment comment
comment-language comment-language
command-override command-override
subsystem subsystem
x11 x11
shell shell
exec exec
agent agent
env env
from from
port-forward port-forward
reverse-forward reverse-forward
5.6 Status codes 5.6. Status codes
The status code is a byte value, describing the status of a request. The status code is a byte value, describing the status of a request.
5.6.1 Conventions 5.6.1. Conventions
Status responses have status codes in the range 0 to 255. These 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 numbers are allocated as follows. Of these, the range 192 to 255 is
reserved for use by local, private extensions. reserved for use by local, private extensions.
5.6.2 Initial Assignments 5.6.2. Initial Assignments
The following table identifies the initial assignments of the status The following table identifies the initial assignments of the status
code values. code values.
Status code Value Reference Status code Value Reference
------------ ----- --------- ------------ ----- ---------
SSH_PUBLICKEY_SUCCESS 0 SSH_PUBLICKEY_SUCCESS 0
SSH_PUBLICKEY_ACCESS_DENIED 1 SSH_PUBLICKEY_ACCESS_DENIED 1
SSH_PUBLICKEY_STORAGE_EXCEEDED 2 SSH_PUBLICKEY_STORAGE_EXCEEDED 2
SSH_PUBLICKEY_VERSION_NOT_SUPPORTED 3 SSH_PUBLICKEY_VERSION_NOT_SUPPORTED 3
SSH_PUBLICKEY_KEY_NOT_FOUND 4 SSH_PUBLICKEY_KEY_NOT_FOUND 4
SSH_PUBLICKEY_KEY_NOT_SUPPORTED 5 SSH_PUBLICKEY_KEY_NOT_SUPPORTED 5
SSH_PUBLICKEY_KEY_ALREADY_PRESENT 6 SSH_PUBLICKEY_KEY_ALREADY_PRESENT 6
SSH_PUBLICKEY_GENERAL_FAILURE 7 SSH_PUBLICKEY_GENERAL_FAILURE 7
SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED 8 SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED 8
SSH_PUBLICKEY_ATTRIBUTE_NOT_SUPPORTED 9
5.6.3 Future Assignments 5.6.3. Future Assignments
Requests for assignments of new message numbers in the range of 0 to 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 191 MUST be done through the STANDARDS ACTION method as described in
[9]. [9].
The IANA will not control the message numbers range of 192 through The IANA will not control the message numbers range of 192 through
255. This range will be left for PRIVATE USE. 255. This range will be left for PRIVATE USE.
6. References 6. References
6.1 Normative References 6.1. Normative References
[1] Lonvick, C., "SSH Protocol Architecture", [1] Ylonen, T. and C. Lonvick, "SSH Protocol Architecture",
Internet-Draft draft-ietf-secsh-architecture-22, March 2005. draft-ietf-secsh-architecture-22 (work in progress), March 2005.
[2] Lonvick, C., "SSH Transport Layer Protocol", [2] Lonvick, C., "SSH Transport Layer Protocol",
Internet-Draft draft-ietf-secsh-transport-24, March 2005. draft-ietf-secsh-transport-24 (work in progress), March 2005.
[3] Lonvick, C., "SSH Authentication Protocol", [3] Lonvick, C. and T. Ylonen, "SSH Authentication Protocol",
Internet-Draft draft-ietf-secsh-userauth-27, March 2005. draft-ietf-secsh-userauth-27 (work in progress), March 2005.
[4] Lonvick, C., "SSH Connection Protocol", [4] Lonvick, C. and T. Ylonen, "SSH Connection Protocol",
Internet-Draft draft-ietf-secsh-connect-25, March 2005. draft-ietf-secsh-connect-25 (work in progress), March 2005.
[5] Alvestrand, H., "Tags for the Identification of Languages", [5] Alvestrand, H., "Tags for the Identification of Languages",
RFC 1766, March 1995. RFC 1766, March 1995.
[6] Yergeau, F., "UTF-8, a transformation format of ISO 10646", [6] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
RFC 2279, January 1998. RFC 2279, January 1998.
6.2 Informative References 6.2. Informative References
[7] Crocker, D., "Standard for the format of ARPA Internet text [7] Crocker, D., "Standard for the format of ARPA Internet text
messages", STD 11, RFC 822, August 1982. messages", STD 11, RFC 822, August 1982.
[8] Mockapetris, P., "Domain names - concepts and facilities", [8] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987. STD 13, RFC 1034, November 1987.
[9] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA [9] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
skipping to change at page 18, line 33 skipping to change at page 18, line 5
Jon Bright Jon Bright
Silicon Circus Silicon Circus
24 Jubilee Road 24 Jubilee Road
Chichester, West Sussex PO19 7XB Chichester, West Sussex PO19 7XB
UK UK
Phone: +49 172 524 0521 Phone: +49 172 524 0521
Email: jon@siliconcircus.com Email: jon@siliconcircus.com
Trademark notice
"ssh" is a registered trademark in the United States and/or other
countries.
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights 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 might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
 End of changes. 

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