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RFC 4250

The Secure Shell (SSH) Protocol Assigned Numbers

Pages: 20
Proposed Standard
Updated by:  82689142

Top   ToC   RFC4250 - Page 1
Network Working Group                                        S. Lehtinen
Request for Comments: 4250              SSH Communications Security Corp
Category: Standards Track                                C. Lonvick, Ed.
                                                     Cisco Systems, Inc.
                                                            January 2006


            The Secure Shell (SSH) Protocol Assigned Numbers

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

This document defines the instructions to the IANA and the initial state of the IANA assigned numbers for the Secure Shell (SSH) protocol. It is intended only for the initialization of the IANA registries referenced in the set of SSH documents.

Table of Contents

1. Introduction ....................................................2 2. Contributors ....................................................3 3. Conventions Used in This Document ...............................3 3.1. RFC 2119 Keywords ..........................................3 3.2. RFC 2434 Keywords ..........................................3 3.3. Protocol Fields and Values .................................4 4. IANA Considerations .............................................5 4.1. Message Numbers ............................................5 4.1.1. Conventions .........................................5 4.1.2. Initial Assignments .................................6 4.1.3. Future Assignments ..................................6 4.2. Disconnection Messages Reason Codes and Descriptions .......7 4.2.1. Conventions .........................................7 4.2.2. Initial Assignments .................................7 4.2.3. Future Assignments ..................................8 4.3. Channel Connection Failure Reason Codes and Descriptions ...8 4.3.1. Conventions .........................................8 4.3.2. Initial Assignments .................................8
Top   ToC   RFC4250 - Page 2
           4.3.3. Future Assignments ..................................8
           4.3.4. Notes about the PRIVATE USE Range ...................9
      4.4. Extended Channel Data Transfer data_type_code and Data .....9
           4.4.1. Conventions .........................................9
           4.4.2. Initial Assignments ................................10
           4.4.3. Future Assignments .................................10
      4.5. Pseudo-Terminal Encoded Terminal Modes ....................10
           4.5.1. Conventions ........................................10
           4.5.2. Initial Assignments ................................10
           4.5.3. Future Assignments .................................12
      4.6. Names .....................................................12
           4.6.1. Conventions for Names ..............................13
           4.6.2. Future Assignments of Names ........................13
      4.7. Service Names .............................................13
      4.8. Authentication Method Names ...............................14
      4.9. Connection Protocol Assigned Names ........................14
           4.9.1. Connection Protocol Channel Types ..................14
           4.9.2. Connection Protocol Global Request Names ...........14
           4.9.3. Connection Protocol Channel Request Names ..........15
           4.9.4. Initial Assignment of Signal Names .................15
           4.9.5. Connection Protocol Subsystem Names ................15
      4.10. Key Exchange Method Names ................................16
      4.11. Assigned Algorithm Names .................................16
           4.11.1. Encryption Algorithm Names ........................16
           4.11.2. MAC Algorithm Names ...............................17
           4.11.3. Public Key Algorithm Names ........................17
           4.11.4. Compression Algorithm Names .......................17
   5. Security Considerations ........................................17
   6. References .....................................................18
      6.1. Normative References ......................................18
      6.2. Informative References ....................................18
   Authors' Addresses ................................................19
   Trademark Notice ..................................................19

1. Introduction

This document does not define any new protocols. It is intended only to create the initial state of the IANA databases for the SSH protocol and also contains instructions for future assignments. Except for one HISTORIC algorithm generally regarded as obsolete, this document does not define any new protocols or number ranges not already defined in: [SSH-ARCH], [SSH-TRANS], [SSH-USERAUTH], [SSH-CONNECT].
Top   ToC   RFC4250 - Page 3

2. Contributors

The major original contributors of this set of documents have been: Tatu Ylonen, Tero Kivinen, Timo J. Rinne, Sami Lehtinen (all of SSH Communications Security Corp), and Markku-Juhani O. Saarinen (University of Jyvaskyla). Darren Moffat was the original editor of this set of documents and also made very substantial contributions. Many people contributed to the development of this document over the years. People who should be acknowledged include Mats Andersson, Ben Harris, Bill Sommerfeld, Brent McClure, Niels Moller, Damien Miller, Derek Fawcus, Frank Cusack, Heikki Nousiainen, Jakob Schlyter, Jeff Van Dyke, Jeffrey Altman, Jeffrey Hutzelman, Jon Bright, Joseph Galbraith, Ken Hornstein, Markus Friedl, Martin Forssen, Nicolas Williams, Niels Provos, Perry Metzger, Peter Gutmann, Simon Josefsson, Simon Tatham, Wei Dai, Denis Bider, der Mouse, and Tadayoshi Kohno. Listing their names here does not mean that they endorse this document, but that they have contributed to it.

3. Conventions Used in This Document

3.1. RFC 2119 Keywords

All documents related to the SSH protocols shall use the keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" to describe requirements. These keywords are to be interpreted as described in [RFC2119].

3.2. RFC 2434 Keywords

The keywords "PRIVATE USE", "HIERARCHICAL ALLOCATION", "FIRST COME FIRST SERVED", "EXPERT REVIEW", "SPECIFICATION REQUIRED", "IESG APPROVAL", "IETF CONSENSUS", and "STANDARDS ACTION" that appear in this document when used to describe namespace allocation are to be interpreted as described in [RFC2434]. These designations are repeated in this document for clarity. PRIVATE USE - For private or local use only, with the type and purpose defined by the local site. No attempt is made to prevent multiple sites from using the same value in different (and incompatible) ways. There is no need for IANA to review such assignments and assignments are not generally useful for interoperability.
Top   ToC   RFC4250 - Page 4
   HIERARCHICAL ALLOCATION - Delegated managers can assign values
   provided they have been given control over that part of the name
   space.  IANA controls the higher levels of the namespace according to
   one of the other policies.

   FIRST COME FIRST SERVED - Anyone can obtain an assigned number, so
   long as they provide a point of contact and a brief description of
   what the value would be used for.  For numbers, the exact value is
   generally assigned by the IANA; with names, specific names are
   usually requested.

   EXPERT REVIEW - approval by a Designated Expert is required.

   SPECIFICATION REQUIRED - Values and their meaning must be documented
   in an RFC or other permanent and readily available reference, in
   sufficient detail so that interoperability between independent
   implementations is possible.

   IESG APPROVAL - New assignments must be approved by the IESG, but
   there is no requirement that the request be documented in an RFC
   (though the IESG has discretion to request documents or other
   supporting materials on a case-by-case basis).

   IETF CONSENSUS - New values are assigned through the IETF consensus
   process.  Specifically, new assignments are made via RFCs approved by
   the IESG.  Typically, the IESG will seek input on prospective
   assignments from appropriate persons (e.g., a relevant Working Group
   if one exists).

   STANDARDS ACTION - Values are assigned only for Standards Track RFCs
   approved by the IESG.

3.3. Protocol Fields and Values

Protocol fields and possible values to fill them are defined in this set of documents. Protocol fields will be defined in the message definitions. As an example, SSH_MSG_CHANNEL_DATA is defined as follows. byte SSH_MSG_CHANNEL_DATA uint32 recipient channel string data Throughout these documents, when the fields are referenced, they will appear within single quotes. When values to fill those fields are referenced, they will appear within double quotes. Using the above example, possible values for 'data' are "foo" and "bar".
Top   ToC   RFC4250 - Page 5

4. IANA Considerations

This entire document is the IANA considerations for the SSH protocol, as defined in [SSH-ARCH], [SSH-TRANS], [SSH-USERAUTH], [SSH-CONNECT]. This section contains conventions used in naming the namespaces, the initial state of the registry, and instructions for future assignments.

4.1. Message Numbers

The Message Number is a byte value that describes the payload of a packet.

4.1.1. Conventions

Protocol packets have message numbers in the range 1 to 255. These numbers are allocated as follows: Transport layer protocol: 1 to 19 Transport layer generic (e.g., disconnect, ignore, debug, etc.) 20 to 29 Algorithm negotiation 30 to 49 Key exchange method specific (numbers can be reused for different authentication methods) User authentication protocol: 50 to 59 User authentication generic 60 to 79 User authentication method specific (numbers can be reused for different authentication methods) Connection protocol: 80 to 89 Connection protocol generic 90 to 127 Channel related messages Reserved for client protocols: 128 to 191 Reserved Local extensions: 192 to 255 Local extensions
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4.1.2. Initial Assignments

The following table identifies the initial assignments of the Message ID values. Message ID Value Reference ----------- ----- --------- SSH_MSG_DISCONNECT 1 [SSH-TRANS] SSH_MSG_IGNORE 2 [SSH-TRANS] SSH_MSG_UNIMPLEMENTED 3 [SSH-TRANS] SSH_MSG_DEBUG 4 [SSH-TRANS] SSH_MSG_SERVICE_REQUEST 5 [SSH-TRANS] SSH_MSG_SERVICE_ACCEPT 6 [SSH-TRANS] SSH_MSG_KEXINIT 20 [SSH-TRANS] SSH_MSG_NEWKEYS 21 [SSH-TRANS] SSH_MSG_USERAUTH_REQUEST 50 [SSH-USERAUTH] SSH_MSG_USERAUTH_FAILURE 51 [SSH-USERAUTH] SSH_MSG_USERAUTH_SUCCESS 52 [SSH-USERAUTH] SSH_MSG_USERAUTH_BANNER 53 [SSH-USERAUTH] SSH_MSG_GLOBAL_REQUEST 80 [SSH-CONNECT] SSH_MSG_REQUEST_SUCCESS 81 [SSH-CONNECT] SSH_MSG_REQUEST_FAILURE 82 [SSH-CONNECT] SSH_MSG_CHANNEL_OPEN 90 [SSH-CONNECT] SSH_MSG_CHANNEL_OPEN_CONFIRMATION 91 [SSH-CONNECT] SSH_MSG_CHANNEL_OPEN_FAILURE 92 [SSH-CONNECT] SSH_MSG_CHANNEL_WINDOW_ADJUST 93 [SSH-CONNECT] SSH_MSG_CHANNEL_DATA 94 [SSH-CONNECT] SSH_MSG_CHANNEL_EXTENDED_DATA 95 [SSH-CONNECT] SSH_MSG_CHANNEL_EOF 96 [SSH-CONNECT] SSH_MSG_CHANNEL_CLOSE 97 [SSH-CONNECT] SSH_MSG_CHANNEL_REQUEST 98 [SSH-CONNECT] SSH_MSG_CHANNEL_SUCCESS 99 [SSH-CONNECT] SSH_MSG_CHANNEL_FAILURE 100 [SSH-CONNECT]

4.1.3. Future Assignments

Requests for assignments of new message numbers in the range of 1 to 29, 50 to 59, and 80 to 127 MUST be done through the STANDARDS ACTION method, as described in [RFC2434]. The meanings of message numbers in the range of 30 to 49 are specific to the key exchange method in use, and their meaning will be specified by the definition of that method.
Top   ToC   RFC4250 - Page 7
   The meanings of message numbers in the range of 60 to 79 are specific
   to the user authentication method in use, and their meaning will be
   specified by the definition of that method.

   Requests for assignments of new message numbers in the range of 128
   to 191 MUST be done through the IETF CONSENSUS method, as described
   in [RFC2434].

   The IANA will not control the message numbers in the range of 192
   through 255.  This range will be left for PRIVATE USE.

4.2. Disconnection Messages Reason Codes and Descriptions

The Disconnection Message 'reason code' is a uint32 value. The associated Disconnection Message 'description' is a human-readable message that describes the disconnect reason.

4.2.1. Conventions

Protocol packets containing the SSH_MSG_DISCONNECT message MUST have Disconnection Message 'reason code' values in the range of 0x00000001 to 0xFFFFFFFF. These are described in [SSH-TRANS].

4.2.2. Initial Assignments

The following table identifies the initial assignments of the SSH_MSG_DISCONNECT 'description' and 'reason code' values. Symbolic Name reason code ------------- ----------- SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1 SSH_DISCONNECT_PROTOCOL_ERROR 2 SSH_DISCONNECT_KEY_EXCHANGE_FAILED 3 SSH_DISCONNECT_RESERVED 4 SSH_DISCONNECT_MAC_ERROR 5 SSH_DISCONNECT_COMPRESSION_ERROR 6 SSH_DISCONNECT_SERVICE_NOT_AVAILABLE 7 SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8 SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9 SSH_DISCONNECT_CONNECTION_LOST 10 SSH_DISCONNECT_BY_APPLICATION 11 SSH_DISCONNECT_TOO_MANY_CONNECTIONS 12 SSH_DISCONNECT_AUTH_CANCELLED_BY_USER 13 SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14 SSH_DISCONNECT_ILLEGAL_USER_NAME 15
Top   ToC   RFC4250 - Page 8

4.2.3. Future Assignments

Disconnection Message 'reason code' values MUST be assigned sequentially. Requests for assignments of new Disconnection Message 'reason code' values, and their associated Disconnection Message 'description' text, in the range of 0x00000010 through 0xFDFFFFFF, MUST be done through the IETF CONSENSUS method, as described in [RFC2434]. The IANA will not assign Disconnection Message 'reason code' values in the range of 0xFE000000 through 0xFFFFFFFF. Disconnection Message 'reason code' values in that range are left for PRIVATE USE, as described in [RFC2434].

4.3. Channel Connection Failure Reason Codes and Descriptions

The Channel Connection Failure 'reason code' is a uint32 value. The associated Channel Connection Failure 'description' text is a human- readable message that describes the channel connection failure reason. This is described in [SSH-CONNECT].

4.3.1. Conventions

Protocol packets containing the SSH_MSG_CHANNEL_OPEN_FAILURE message MUST have Channel Connection Failure 'reason code' values in the range of 0x00000001 to 0xFFFFFFFF.

4.3.2. Initial Assignments

The initial assignments for the 'reason code' values and 'description' values are given in the table below. Note that the values for the 'reason code' are given in decimal format for readability, but they are actually uint32 values. Symbolic Name reason code ------------- ----------- SSH_OPEN_ADMINISTRATIVELY_PROHIBITED 1 SSH_OPEN_CONNECT_FAILED 2 SSH_OPEN_UNKNOWN_CHANNEL_TYPE 3 SSH_OPEN_RESOURCE_SHORTAGE 4

4.3.3. Future Assignments

Channel Connection Failure 'reason code' values MUST be assigned sequentially. Requests for assignments of new Channel Connection Failure 'reason code' values, and their associated Channel Connection Failure 'description string', in the range of 0x00000005 to 0xFDFFFFFF MUST be done through the IETF CONSENSUS method, as described in [RFC2434]. The IANA will not assign Channel Connection
Top   ToC   RFC4250 - Page 9
   Failure 'reason code' values in the range of 0xFE000000 to
   0xFFFFFFFF.  Channel Connection Failure 'reason code' values in that
   range are left for PRIVATE USE, as described in [RFC2434].

4.3.4. Notes about the PRIVATE USE Range

While it is understood that the IANA will have no control over the range of 0xFE000000 to 0xFFFFFFFF, this range will be split in two parts and administered by the following conventions. o The range of 0xFE000000 to 0xFEFFFFFF is to be used in conjunction with locally assigned channels. For example, if a channel is proposed with a 'channel type' of "example_session@example.com" but fails, then the server will respond with either a 'reason code' assigned by the IANA (as listed above and in the range of 0x00000001 to 0xFDFFFFFF), or with a locally assigned value in the range of 0xFE000000 to 0xFEFFFFFF. Naturally, if the server does not understand the proposed 'channel type', even if it is a locally defined 'channel type', then the 'reason code' MUST be 0x00000003, as described above. If the server does understand the 'channel type', but the channel still fails to open, then the server SHOULD respond with a locally assigned 'reason code' value that is consistent with the proposed local 'channel type'. It is assumed that practitioners will first attempt to use the IANA- assigned 'reason code' values and then document their locally assigned 'reason code' values. o There are no restrictions or suggestions for the range starting with 0xFF. No interoperability is expected for anything used in this range. Essentially, it is for experimentation.

4.4. Extended Channel Data Transfer data_type_code and Data

The Extended Channel Data Transfer 'data_type_code' is a uint32 value. The associated Extended Channel Data Transfer 'data' is a human-readable message that describes the type of data allowed to be transferred in the channel.

4.4.1. Conventions

Protocol packets containing the SSH_MSG_CHANNEL_EXTENDED_DATA message MUST have Extended Channel Data Transfer 'data_type_code' values in the range of 0x00000001 to 0xFFFFFFFF. This is described in [SSH-CONNECT].
Top   ToC   RFC4250 - Page 10

4.4.2. Initial Assignments

The initial assignments for the 'data_type_code' values and 'data' values are given in the table below. Note that the value for the 'data_type_code' is given in decimal format for readability, but the values are actually uint32 values. Symbolic name data_type_code ------------- -------------- SSH_EXTENDED_DATA_STDERR 1

4.4.3. Future Assignments

Extended Channel Data Transfer 'data_type_code' values MUST be assigned sequentially. Requests for assignments of new Extended Channel Data Transfer 'data_type_code' values, and their associated Extended Channel Data Transfer 'data' strings, in the range of 0x00000002 to 0xFDFFFFFF, MUST be done through the IETF CONSENSUS method, as described in [RFC2434]. The IANA will not assign Extended Channel Data Transfer 'data_type_code' values in the range of 0xFE000000 to 0xFFFFFFFF. Extended Channel Data Transfer 'data_type_code' values in that range are left for PRIVATE USE, as described in [RFC2434].

4.5. Pseudo-Terminal Encoded Terminal Modes

SSH_MSG_CHANNEL_REQUEST messages with a "pty-req" string MUST contain 'encoded terminal modes'. The 'encoded terminal modes' value is a byte stream of opcode-argument pairs.

4.5.1. Conventions

Protocol packets containing the SSH_MSG_CHANNEL_REQUEST message with a "pty-req" string MUST contain an 'encoded terminal modes' value. The opcode values consist of a single byte and are in the range of 1 to 255. Opcodes 1 to 159 have a uint32 argument. Opcodes 160 to 255 are not yet defined.

4.5.2. Initial Assignments

The following table identifies the initial assignments of the opcode values that are used in the 'encoded terminal modes' value.
Top   ToC   RFC4250 - Page 11
         opcode  mnemonic       description
         ------  --------       -----------
         0     TTY_OP_END  Indicates end of options.
         1     VINTR       Interrupt character; 255 if none.  Similarly
                            for the other characters.  Not all of these
                            characters are supported on all systems.
         2     VQUIT       The quit character (sends SIGQUIT signal on
                            POSIX systems).
         3     VERASE      Erase the character to left of the cursor.
         4     VKILL       Kill the current input line.
         5     VEOF        End-of-file character (sends EOF from the
                            terminal).
         6     VEOL        End-of-line character in addition to
                            carriage return and/or linefeed.
         7     VEOL2       Additional end-of-line character.
         8     VSTART      Continues paused output (normally
                            control-Q).
         9     VSTOP       Pauses output (normally control-S).
         10    VSUSP       Suspends the current program.
         11    VDSUSP      Another suspend character.
         12    VREPRINT    Reprints the current input line.
         13    VWERASE     Erases a word left of cursor.
         14    VLNEXT      Enter the next character typed literally,
                            even if it is a special character
         15    VFLUSH      Character to flush output.
         16    VSWTCH      Switch to a different shell layer.
         17    VSTATUS     Prints system status line (load, command,
                            pid, etc).
         18    VDISCARD    Toggles the flushing of terminal output.
         30    IGNPAR      The ignore parity flag.  The parameter
                            SHOULD be 0 if this flag is FALSE,
                            and 1 if it is TRUE.
         31    PARMRK      Mark parity and framing errors.
         32    INPCK       Enable checking of parity errors.
         33    ISTRIP      Strip 8th bit off characters.
         34    INLCR       Map NL into CR on input.
         35    IGNCR       Ignore CR on input.
         36    ICRNL       Map CR to NL on input.
         37    IUCLC       Translate uppercase characters to
                            lowercase.
         38    IXON        Enable output flow control.
         39    IXANY       Any char will restart after stop.
         40    IXOFF       Enable input flow control.
         41    IMAXBEL     Ring bell on input queue full.
         50    ISIG        Enable signals INTR, QUIT, [D]SUSP.
         51    ICANON      Canonicalize input lines.
Top   ToC   RFC4250 - Page 12
         52    XCASE       Enable input and output of uppercase
                            characters by preceding their lowercase
                            equivalents with "\".
         53    ECHO        Enable echoing.
         54    ECHOE       Visually erase chars.
         55    ECHOK       Kill character discards current line.
         56    ECHONL      Echo NL even if ECHO is off.
         57    NOFLSH      Don't flush after interrupt.
         58    TOSTOP      Stop background jobs from output.
         59    IEXTEN      Enable extensions.
         60    ECHOCTL     Echo control characters as ^(Char).
         61    ECHOKE      Visual erase for line kill.
         62    PENDIN      Retype pending input.
         70    OPOST       Enable output processing.
         71    OLCUC       Convert lowercase to uppercase.
         72    ONLCR       Map NL to CR-NL.
         73    OCRNL       Translate carriage return to newline
                            (output).
         74    ONOCR       Translate newline to carriage
                            return-newline (output).
         75    ONLRET      Newline performs a carriage return
                            (output).
         90    CS7         7 bit mode.
         91    CS8         8 bit mode.
         92    PARENB      Parity enable.
         93    PARODD      Odd parity, else even.

         128 TTY_OP_ISPEED  Specifies the input baud rate in
                             bits per second.
         129 TTY_OP_OSPEED  Specifies the output baud rate in
                             bits per second.

4.5.3. Future Assignments

Requests for assignments of new opcodes and their associated arguments MUST be done through the IETF CONSENSUS method, as described in [RFC2434].

4.6. 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.
Top   ToC   RFC4250 - Page 13

4.6.1. 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 (","), whitespace, control characters (ASCII codes 32 or less), or the ASCII code 127 (DEL). 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 preceding 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 (","), whitespace, control characters (ASCII codes 32 or less), or the ASCII code 127 (DEL). They MUST have only a single at-sign in them. The part following the at-sign MUST be a valid, fully qualified internet domain name [RFC1034] 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 [RFC0822] email addresses. This is purely coincidental and has nothing to do with STD 11 [RFC0822]. An example of a locally defined name is "ourcipher-cbc@example.com" (without the double quotes).

4.6.2. Future Assignments of Names

Requests for assignments of new names MUST be done through the IETF CONSENSUS method, as described in [RFC2434].

4.7. Service Names

The 'service name' is used to describe a protocol layer. The following table lists the initial assignments of the 'service name' values. Service Name Reference ------------- --------- ssh-userauth [SSH-USERAUTH] ssh-connection [SSH-CONNECT]
Top   ToC   RFC4250 - Page 14

4.8. Authentication Method Names

The Authentication Method Name is used to describe an authentication method for the "ssh-userauth" service [SSH-USERAUTH]. The following table identifies the initial assignments of the Authentication Method Names. Method Name Reference ------------ --------- publickey [SSH-USERAUTH, Section 7] password [SSH-USERAUTH, Section 8] hostbased [SSH-USERAUTH, Section 9] none [SSH-USERAUTH, Section 5.2]

4.9. Connection Protocol Assigned Names

The following table lists the initial assignments to the Connection Protocol Type and Request names.

4.9.1. Connection Protocol Channel Types

The following table lists the initial assignments of the Connection Protocol Channel Types. Channel type Reference ------------ --------- session [SSH-CONNECT, Section 6.1] x11 [SSH-CONNECT, Section 6.3.2] forwarded-tcpip [SSH-CONNECT, Section 7.2] direct-tcpip [SSH-CONNECT, Section 7.2]

4.9.2. Connection Protocol Global Request Names

The following table lists the initial assignments of the Connection Protocol Global Request Names. Request type Reference ------------ --------- tcpip-forward [SSH-CONNECT, Section 7.1] cancel-tcpip-forward [SSH-CONNECT, Section 7.1]
Top   ToC   RFC4250 - Page 15

4.9.3. Connection Protocol Channel Request Names

The following table lists the initial assignments of the Connection Protocol Channel Request Names. Request type Reference ------------ --------- pty-req [SSH-CONNECT, Section 6.2] x11-req [SSH-CONNECT, Section 6.3.1] env [SSH-CONNECT, Section 6.4] shell [SSH-CONNECT, Section 6.5] exec [SSH-CONNECT, Section 6.5] subsystem [SSH-CONNECT, Section 6.5] window-change [SSH-CONNECT, Section 6.7] xon-xoff [SSH-CONNECT, Section 6.8] signal [SSH-CONNECT, Section 6.9] exit-status [SSH-CONNECT, Section 6.10] exit-signal [SSH-CONNECT, Section 6.10]

4.9.4. Initial Assignment of Signal Names

The following table lists the initial assignments of the Signal Names. Signal Reference ------ --------- ABRT [SSH-CONNECT] ALRM [SSH-CONNECT] FPE [SSH-CONNECT] HUP [SSH-CONNECT] ILL [SSH-CONNECT] INT [SSH-CONNECT] KILL [SSH-CONNECT] PIPE [SSH-CONNECT] QUIT [SSH-CONNECT] SEGV [SSH-CONNECT] TERM [SSH-CONNECT] USR1 [SSH-CONNECT] USR2 [SSH-CONNECT]

4.9.5. Connection Protocol Subsystem Names

There are no initial assignments of the Connection Protocol Subsystem Names.
Top   ToC   RFC4250 - Page 16

4.10. Key Exchange Method Names

The name "diffie-hellman-group1-sha1" is used for a key exchange method using an Oakley group, as defined in [RFC2409]. SSH maintains its own group identifier space, which is logically distinct from Oakley [RFC2412] and IKE; however, for one additional group, the Working Group adopted the number assigned by [RFC3526], using "diffie-hellman-group14-sha1" for the name of the second defined group. Implementations should treat these names as opaque identifiers and should not assume any relationship between the groups used by SSH and the groups defined for IKE. The following table identifies the initial assignments of the key exchange methods. Method name Reference ------------ --------- diffie-hellman-group1-sha1 [SSH-TRANS, Section 8.1] diffie-hellman-group14-sha1 [SSH-TRANS, Section 8.2]

4.11. Assigned Algorithm Names

4.11.1. Encryption Algorithm Names

The following table identifies the initial assignment of the Encryption Algorithm Names. Encryption Algorithm Name Reference ------------------------- --------- 3des-cbc [SSH-TRANS, Section 6.3] blowfish-cbc [SSH-TRANS, Section 6.3] twofish256-cbc [SSH-TRANS, Section 6.3] twofish-cbc [SSH-TRANS, Section 6.3] twofish192-cbc [SSH-TRANS, Section 6.3] twofish128-cbc [SSH-TRANS, Section 6.3] aes256-cbc [SSH-TRANS, Section 6.3] aes192-cbc [SSH-TRANS, Section 6.3] aes128-cbc [SSH-TRANS, Section 6.3] serpent256-cbc [SSH-TRANS, Section 6.3] serpent192-cbc [SSH-TRANS, Section 6.3] serpent128-cbc [SSH-TRANS, Section 6.3] arcfour [SSH-TRANS, Section 6.3] idea-cbc [SSH-TRANS, Section 6.3] cast128-cbc [SSH-TRANS, Section 6.3] none [SSH-TRANS, Section 6.3] des-cbc [FIPS-46-3] HISTORIC; See page 4 of [FIPS-46-3]
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4.11.2. MAC Algorithm Names

The following table identifies the initial assignments of the MAC Algorithm Names. MAC Algorithm Name Reference ------------------ --------- hmac-sha1 [SSH-TRANS, Section 6.4] hmac-sha1-96 [SSH-TRANS, Section 6.4] hmac-md5 [SSH-TRANS, Section 6.4] hmac-md5-96 [SSH-TRANS, Section 6.4] none [SSH-TRANS, Section 6.4]

4.11.3. Public Key Algorithm Names

The following table identifies the initial assignments of the Public Key Algorithm names. Public Key Algorithm Name Reference ------------------------- --------- ssh-dss [SSH-TRANS, Section 6.6] ssh-rsa [SSH-TRANS, Section 6.6] pgp-sign-rsa [SSH-TRANS, Section 6.6] pgp-sign-dss [SSH-TRANS, Section 6.6]

4.11.4. Compression Algorithm Names

The following table identifies the initial assignments of the Compression Algorithm names. Compression Algorithm Name Reference -------------------------- --------- none [SSH-TRANS, Section 6.2] zlib [SSH-TRANS, Section 6.2]

5. Security Considerations

This protocol provides a secure encrypted channel over an insecure network. Full security considerations for this protocol are provided in [SSH-ARCH].
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6. References

6.1. Normative References

[SSH-ARCH] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Protocol Architecture", RFC 4251, January 2006. [SSH-TRANS] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Transport Layer Protocol", RFC 4253, January 2006. [SSH-USERAUTH] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Authentication Protocol", RFC 4252, January 2006. [SSH-CONNECT] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH) Connection Protocol", RFC 4254, January 2006. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2409] Harkins, D. and D. Carrel, "The Internet Key Exchange (IKE)", RFC 2409, November 1998. [RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. [RFC3526] Kivinen, T. and M. Kojo, "More Modular Exponential (MODP) Diffie-Hellman groups for Internet Key Exchange (IKE)", RFC 3526, May 2003.

6.2. Informative References

[RFC0822] Crocker, D., "Standard for the format of ARPA Internet text messages", STD 11, RFC 822, August 1982. [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987. [RFC2412] Orman, H., "The OAKLEY Key Determination Protocol", RFC 2412, November 1998. [FIPS-46-3] US National Institute of Standards and Technology, "Data Encryption Standard (DES)", Federal Information Processing Standards Publication 46-3, October 1999.
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Authors' Addresses

Sami Lehtinen SSH Communications Security Corp Valimotie 17 00380 Helsinki Finland EMail: sjl@ssh.com Chris Lonvick (editor) Cisco Systems, Inc. 12515 Research Blvd. Austin 78759 USA EMail: clonvick@cisco.com Trademark Notice "ssh" is a registered trademark in the United States and/or other countries.
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