Secure Shell (SSH) Protocol Parameters

Created

  • 2005-06-02

Last Updated

  • 2026-09-08

Available Formats

Message Numbers

Registration Procedure(s)

  • Standards Action

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers

Available Formats

Value Message ID Reference
0 Reserved
1 SSH_MSG_DISCONNECT RFC 4253
2 SSH_MSG_IGNORE RFC 4253
3 SSH_MSG_UNIMPLEMENTED RFC 4253
4 SSH_MSG_DEBUG RFC 4253
5 SSH_MSG_SERVICE_REQUEST RFC 4253
6 SSH_MSG_SERVICE_ACCEPT RFC 4253
7 SSH_MSG_EXT_INFO RFC 8308
8 SSH_MSG_NEWCOMPRESS RFC 8308
9-19 Unassigned (Transport layer generic)
20 SSH_MSG_KEXINIT RFC 4253
21 SSH_MSG_NEWKEYS RFC 4253
22-29 Unassigned (Algorithm negotiation)
30-49 Reserved (key exchange method specific) RFC 4251
50 SSH_MSG_USERAUTH_REQUEST RFC 4252
51 SSH_MSG_USERAUTH_FAILURE RFC 4252
52 SSH_MSG_USERAUTH_SUCCESS RFC 4252
53 SSH_MSG_USERAUTH_BANNER RFC 4252
54-59 Unassigned (User authentication generic)
60 SSH_MSG_USERAUTH_INFO_REQUEST RFC 4256
61 SSH_MSG_USERAUTH_INFO_RESPONSE RFC 4256
62-79 Reserved (User authentication method specific) RFC 4251
80 SSH_MSG_GLOBAL_REQUEST RFC 4254
81 SSH_MSG_REQUEST_SUCCESS RFC 4254
82 SSH_MSG_REQUEST_FAILURE RFC 4254
83-89 Unassigned (Connection protocol generic)
90 SSH_MSG_CHANNEL_OPEN RFC 4254
91 SSH_MSG_CHANNEL_OPEN_CONFIRMATION RFC 4254
92 SSH_MSG_CHANNEL_OPEN_FAILURE RFC 4254
93 SSH_MSG_CHANNEL_WINDOW_ADJUST RFC 4254
94 SSH_MSG_CHANNEL_DATA RFC 4254
95 SSH_MSG_CHANNEL_EXTENDED_DATA RFC 4254
96 SSH_MSG_CHANNEL_EOF RFC 4254
97 SSH_MSG_CHANNEL_CLOSE RFC 4254
98 SSH_MSG_CHANNEL_REQUEST RFC 4254
99 SSH_MSG_CHANNEL_SUCCESS RFC 4254
100 SSH_MSG_CHANNEL_FAILURE RFC 4254
101-127 Unassigned (Channel related messages)
128-191 Reserved (for client protocols)
192-255 Reserved for Private Use (local extensions)

Disconnection Messages Reason Codes and Descriptions

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

SSH_MSG_DISCONNECT 'description' and 'reason code' values

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Range Registration Procedures
0x00000001-0xFDFFFFFF Expert Review
0xFE000000-0xFFFFFFFF Reserved for Private Use
Reason Code Symbolic Name Reference
0x00000000 Reserved
0x00000001 SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT RFC 4253
0x00000002 SSH_DISCONNECT_PROTOCOL_ERROR RFC 4253
0x00000003 SSH_DISCONNECT_KEY_EXCHANGE_FAILED RFC 4253
0x00000004 SSH_DISCONNECT_RESERVED RFC 4253
0x00000005 SSH_DISCONNECT_MAC_ERROR RFC 4253
0x00000006 SSH_DISCONNECT_COMPRESSION_ERROR RFC 4253
0x00000007 SSH_DISCONNECT_SERVICE_NOT_AVAILABLE RFC 4253
0x00000008 SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED RFC 4253
0x00000009 SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE RFC 4253
0x0000000A SSH_DISCONNECT_CONNECTION_LOST RFC 4253
0x0000000B SSH_DISCONNECT_BY_APPLICATION RFC 4253
0x0000000C SSH_DISCONNECT_TOO_MANY_CONNECTIONS RFC 4253
0x0000000D SSH_DISCONNECT_AUTH_CANCELLED_BY_USER RFC 4253
0x0000000E SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE RFC 4253
0x0000000F SSH_DISCONNECT_ILLEGAL_USER_NAME RFC 4253
0x00000010-0xFDFFFFFF Unassigned
0xFE000000-0xFFFFFFFF Reserved for Private Use

Channel Connection Failure Reason Codes and Descriptions

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

'reason code' values and 'description' values

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Range Registration Procedures
0x00000001-0xFDFFFFFF Expert Review
0xFE000000-0xFFFFFFFF Reserved for Private Use
Reason Code Symbolic Name Reference
0x00000000 Reserved
0x00000001 SSH_OPEN_ADMINISTRATIVELY_PROHIBITED RFC 4254
0x00000002 SSH_OPEN_CONNECT_FAILED RFC 4254
0x00000003 SSH_OPEN_UNKNOWN_CHANNEL_TYPE RFC 4254
0x00000004 SSH_OPEN_RESOURCE_SHORTAGE RFC 4254
0x00000005-0xFDFFFFFF Unassigned
0xFE000000-0xFFFFFFFF Reserved for Private Use

Extended Channel Data Transfer data_type_code and Data

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

'data_type_code' values and 'data' values

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Range Registration Procedures
0x00000001-0xFDFFFFFF Expert Review
0xFE000000-0xFFFFFFFF Reserved for Private Use
data_type_code Symbolic Name Reference
0x00000000 Reserved
0x00000001 SSH_EXTENDED_DATA_STDERR RFC 4254
0x00000002-0xFDFFFFFF Unassigned
0xFE000000-0xFFFFFFFF Reserved for Private Use

Pseudo-Terminal Encoded Terminal Modes

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

opcode and argument values which make up the "encoded terminal modes" values

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Opcode Argument Description Reference Note
0 TTY_OP_END Indicates end of options. RFC 4250
1 VINTR Interrupt character; 255 if none. Similarly for the other characters. Not all of these characters are supported on all systems. RFC 4254 Section 8
2 VQUIT The quit character (sends SIGQUIT signal on POSIX systems). RFC 4254 Section 8
3 VERASE Erase the character to left of the cursor. RFC 4254 Section 8
4 VKILL Kill the current input line. RFC 4254 Section 8
5 VEOF End-of-file character (sends EOF from the terminal). RFC 4254 Section 8
6 VEOL End-of-line character in addition to carriage return and/or linefeed. RFC 4254 Section 8
7 VEOL2 Additional end-of-line character. RFC 4254 Section 8
8 VSTART Continues paused output (normally control-Q). RFC 4254 Section 8
9 VSTOP Pauses output (normally control-S). RFC 4254 Section 8
10 VSUSP Suspends the current program. RFC 4254 Section 8
11 VDSUSP Another suspend character. RFC 4254 Section 8
12 VREPRINT Reprints the current input line. RFC 4254 Section 8
13 VWERASE Erases a word left of cursor. RFC 4254 Section 8
14 VLNEXT Enter the next character typed literally, even if it is a special character RFC 4254 Section 8
15 VFLUSH Character to flush output. RFC 4254 Section 8
16 VSWTCH Switch to a different shell layer. RFC 4254 Section 8
17 VSTATUS Prints system status line (load, command, pid, etc). RFC 4254 Section 8
18 VDISCARD Toggles the flushing of terminal output. RFC 4254 Section 8
19-29 Unassigned
30 IGNPAR The ignore parity flag. The parameter SHOULD be 0 if this flag is FALSE, and 1 if it is TRUE. RFC 4254 Section 8
31 PARMRK Mark parity and framing errors. RFC 4254 Section 8
32 INPCK Enable checking of parity errors. RFC 4254 Section 8
33 ISTRIP Strip 8th bit off characters. RFC 4254 Section 8
34 INLCR Map NL into CR on input. RFC 4254 Section 8
35 IGNCR Ignore CR on input. RFC 4254 Section 8
36 ICRNL Map CR to NL on input. RFC 4254 Section 8
37 IUCLC Translate uppercase characters to lowercase. RFC 4254 Section 8
38 IXON Enable output flow control. RFC 4254 Section 8
39 IXANY Any char will restart after stop. RFC 4254 Section 8
40 IXOFF Enable input flow control. RFC 4254 Section 8
41 IMAXBEL Ring bell on input queue full. RFC 4254 Section 8
42 IUTF8 Terminal input and output is assumed to be encoded in UTF-8. RFC 8160
43-49 Unassigned
50 ISIG Enable signals INTR, QUIT, [D]SUSP. RFC 4254 Section 8
51 ICANON Canonicalize input lines. RFC 4254 Section 8
52 XCASE Enable input and output of uppercase characters by preceding their lowercase equivalents with "\". RFC 4254 Section 8
53 ECHO Enable echoing. RFC 4254 Section 8
54 ECHOE Visually erase chars. RFC 4254 Section 8
55 ECHOK Kill character discards current line. RFC 4254 Section 8
56 ECHONL Echo NL even if ECHO is off. RFC 4254 Section 8
57 NOFLSH Don't flush after interrupt. RFC 4254 Section 8
58 TOSTOP Stop background jobs from output. RFC 4254 Section 8
59 IEXTEN Enable extensions. RFC 4254 Section 8
60 ECHOCTL Echo control characters as ^(Char). RFC 4254 Section 8
61 ECHOKE Visual erase for line kill. RFC 4254 Section 8
62 PENDIN Retype pending input. RFC 4254 Section 8
63-69 Unassigned
70 OPOST Enable output processing. RFC 4254 Section 8
71 OLCUC Convert lowercase to uppercase. RFC 4254 Section 8
72 ONLCR Map NL to CR-NL. RFC 4254 Section 8
73 OCRNL Translate carriage return to newline (output). RFC 4254 Section 8
74 ONOCR Translate newline to carriage return-newline (output). RFC 4254 Section 8
75 ONLRET Newline performs a carriage return (output). RFC 4254 Section 8
76-89 Unassigned
90 CS7 7 bit mode. RFC 4254 Section 8
91 CS8 8 bit mode. RFC 4254 Section 8
92 PARENB Parity enable. RFC 4254 Section 8
93 PARODD Odd parity, else even. RFC 4254 Section 8
94-127 Unassigned
128 TTY_OP_ISPEED Specifies the input baud rate in bits per second. RFC 4254 Section 8
129 TTY_OP_OSPEED Specifies the output baud rate in bits per second. RFC 4254 Section 8
130-255 Unassigned

Service Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Service Name Reference
ssh-userauth RFC 4252
ssh-connection RFC 4254

Authentication Method Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Method Name Reference Note
publickey RFC 4252 Section 7
password RFC 4252 Section 8
hostbased RFC 4252 Section 9
none RFC 4252 Section 5.2
keyboard-interactive RFC 4256
gssapi-with-mic RFC 4462
gssapi-keyex RFC 4462
gssapi RFC 4462
external-keyx RFC 4462

Connection Protocol Channel Types

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Channel Type Reference Note
session RFC 4254 Section 6.1
x11 RFC 4254 Section 6.3.2
forwarded-tcpip RFC 4254 Section 7.2
direct-tcpip RFC 4254 Section 7.2
agent-connect RFC 9987 Section 7.3

Connection Protocol Global Request Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Request Type Reference Note
tcpip-forward RFC 4254 Section 7.1
cancel-tcpip-forward RFC 4254 Section 7.1

Connection Protocol Channel Request Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Request Type Reference Note
pty-req RFC 4254 Section 6.2
x11-req RFC 4254 Section 6.3.1
env RFC 4254 Section 6.4
shell RFC 4254 Section 6.5
exec RFC 4254 Section 6.5
subsystem RFC 4254 Section 6.5
window-change RFC 4254 Section 6.7
xon-xoff RFC 4254 Section 6.8
signal RFC 4254 Section 6.9
exit-status RFC 4254 Section 6.10
exit-signal RFC 4254 Section 6.10
break RFC 4335
agent-req RFC 9987 Section 7.2

Signal Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Signal Reference
ABRT RFC 4254
ALRM RFC 4254
FPE RFC 4254
HUP RFC 4254
ILL RFC 4254
INT RFC 4254
KILL RFC 4254
PIPE RFC 4254
QUIT RFC 4254
SEGV RFC 4254
TERM RFC 4254
USR1 RFC 4254
USR2 RFC 4254

Connection Protocol Subsystem Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Subsystem Name Reference
publickey RFC 4819
snmp RFC 5592
netconf RFC 6242
rpki-rtr RFC 6810

Key Exchange Method Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9142: Key Exchange (KEX) Method Updates and Recommendations for Secure Shell (SSH)
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

*All values beginning with the specified string and not containing "@".

Note

“OK to Implement” guidance entries for registrations that pre-date RFC 9142 are found in Table 12 in Section 4 of RFC 9142.

Note

When this registry is modified, the YANG module "iana-ssh-key-exchange-algs" YANG Parameters must be updated as defined in RFC 9644.

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Method Name Reference Note OK to Implement
diffie-hellman-group-exchange-sha1 RFC 4419; RFC 8270 Section 4.1 SHOULD NOT
diffie-hellman-group-exchange-sha256 RFC 4419; RFC 8270 Section 4.2 MAY
diffie-hellman-group1-sha1 RFC 4253 Section 8.1 SHOULD NOT
diffie-hellman-group14-sha1 RFC 4253 Section 8.2 MAY
diffie-hellman-group14-sha256 RFC 8268 MUST
diffie-hellman-group15-sha512 RFC 8268 MAY
diffie-hellman-group16-sha512 RFC 8268 SHOULD
diffie-hellman-group17-sha512 RFC 8268 MAY
diffie-hellman-group18-sha512 RFC 8268 MAY
ecdh-sha2-* RFC 5656 MAY
ecmqv-sha2 RFC 5656 MAY
gss-group1-sha1-* RFC 4462; RFC 8732 SHOULD NOT
gss-group14-sha1-* RFC 4462; RFC 8732 SHOULD NOT
gss-gex-sha1-* RFC 4462; RFC 8732 SHOULD NOT
gss- RFC 4462 Section 2.6 reserved
rsa1024-sha1 RFC 4432 MUST NOT
rsa2048-sha256 RFC 4432 MAY
ext-info-s RFC 8308 Section 2 SHOULD
ext-info-c RFC 8308 Section 2 SHOULD
gss-group14-sha256-* RFC 8732 SHOULD
gss-group15-sha512-* RFC 8732 MAY
gss-group16-sha512-* RFC 8732 MAY
gss-group17-sha512-* RFC 8732 MAY
gss-group18-sha512-* RFC 8732 MAY
gss-nistp256-sha256-* RFC 8732 SHOULD
gss-nistp384-sha384-* RFC 8732 SHOULD
gss-nistp521-sha512-* RFC 8732 SHOULD
gss-curve25519-sha256-* RFC 8732 SHOULD
gss-curve448-sha512-* RFC 8732 MAY
curve25519-sha256 RFC 8731 SHOULD
curve448-sha512 RFC 8731 MAY
ecdh-sha2-nistp256 RFC 5656 SHOULD
ecdh-sha2-nistp384 RFC 5656 SHOULD
ecdh-sha2-nistp521 RFC 5656 SHOULD
sntrup761x25519-sha512 RFC 9941 SHOULD
mlkem768nistp256-sha256 RFC 10042 SHOULD
mlkem1024nistp384-sha384 RFC 10042 SHOULD
mlkem768x25519-sha256 RFC 10042 SHOULD
mlkem512-sha256 draft-harrison-mlkem-ssh-01 MAY
mlkem768-sha256 draft-harrison-mlkem-ssh-01 MAY
mlkem1024-sha384 draft-harrison-mlkem-ssh-01 MAY

Encryption Algorithm Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

When this registry is modified, the YANG module "iana-ssh-encryption-algs" YANG Parameters must be updated as defined in RFC 9644.

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Encryption Algorithm Name Reference Note
3des-cbc RFC 4253 Section 6.3
blowfish-cbc RFC 4253 Section 6.3
twofish256-cbc RFC 4253 Section 6.3
twofish-cbc RFC 4253 Section 6.3
twofish192-cbc RFC 4253 Section 6.3
twofish128-cbc RFC 4253 Section 6.3
aes256-cbc RFC 4253 Section 6.3
aes192-cbc RFC 4253 Section 6.3
aes128-cbc RFC 4253 Section 6.3
serpent256-cbc RFC 4253 Section 6.3
serpent192-cbc RFC 4253 Section 6.3
serpent128-cbc RFC 4253 Section 6.3
arcfour RFC 8758 HISTORIC
idea-cbc RFC 4253 Section 6.3
cast128-cbc RFC 4253 Section 6.3
none RFC 4253 Section 6.3
des-cbc FIPS-46-3 HISTORIC, See page 4
arcfour128 RFC 8758 HISTORIC
arcfour256 RFC 8758 HISTORIC
aes128-ctr RFC 4344
aes192-ctr RFC 4344
aes256-ctr RFC 4344
3des-ctr RFC 4344
blowfish-ctr RFC 4344
twofish128-ctr RFC 4344
twofish192-ctr RFC 4344
twofish256-ctr RFC 4344
serpent128-ctr RFC 4344
serpent192-ctr RFC 4344
serpent256-ctr RFC 4344
idea-ctr RFC 4344
cast128-ctr RFC 4344
AEAD_AES_128_GCM RFC 5647 Section 6.1
AEAD_AES_256_GCM RFC 5647 Section 6.2
chacha20-poly1305 draft-josefsson-ssh-chacha20-poly1305-openssh-01

MAC Algorithm Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

When this registry is modified, the YANG module "iana-ssh-mac-algs" YANG Parameters must be updated as defined in RFC 9644.

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

MAC Algorithm Name Reference Note
hmac-sha1 RFC 4253 Section 6.4
hmac-sha1-96 RFC 4253 Section 6.4
hmac-md5 RFC 4253 Section 6.4
hmac-md5-96 RFC 4253 Section 6.4
none RFC 4253 Section 6.4
AEAD_AES_128_GCM RFC 5647 Section 6.1
AEAD_AES_256_GCM RFC 5647 Section 6.2
hmac-sha2-256 RFC 6668 Section 2
hmac-sha2-512 RFC 6668 Section 2

Public Key Algorithm Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

*All values beginning with the specified string and not containing "@".

Note

When this registry is modified, the YANG module "iana-ssh-public-key-algs" YANG Parameters must be updated as defined in RFC 9644.

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Public Key Algorithm Name Public Key Format Reference Note
ssh-dss ssh-dss RFC 4253 Section 6.6
ssh-rsa ssh-rsa RFC 4253 Section 6.6
rsa-sha2-256 ssh-rsa RFC 8332 Section 3
rsa-sha2-512 ssh-rsa RFC 8332 Section 3
spki-sign-rsa spki-sign-rsa RFC 4253 Section 6.6
spki-sign-dss spki-sign-dss RFC 4253 Section 6.6
pgp-sign-rsa pgp-sign-rsa RFC 4253 Section 6.6
pgp-sign-dss pgp-sign-dss RFC 4253 Section 6.6
null null RFC 4462 Section 5
ecdsa-sha2-* ecdsa-sha2-* RFC 5656
x509v3-ssh-dss x509v3-ssh-dss RFC 6187
x509v3-ssh-rsa x509v3-ssh-rsa RFC 6187
x509v3-rsa2048-sha256 x509v3-rsa2048-sha256 RFC 6187
x509v3-ecdsa-sha2-* x509v3-ecdsa-sha2-* RFC 6187
ssh-ed25519 ssh-ed25519 RFC 8709
ssh-ed448 ssh-ed448 RFC 8709
ssh-mldsa-44 ssh-mldsa-44 draft-sfluhrer-ssh-mldsa-08
ssh-mldsa-65 ssh-mldsa-65 draft-sfluhrer-ssh-mldsa-08
ssh-mldsa-87 ssh-mldsa-87 draft-sfluhrer-ssh-mldsa-08
ssh-mldsa44-ed25519 ssh-mldsa44-ed25519 draft-ietf-sshm-composite-sigs-00
ssh-mldsa87-p384 ssh-mldsa87-p384 draft-ietf-sshm-composite-sigs-00

Compression Algorithm Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4250: The Secure Shell (SSH) Protocol Assigned Numbers
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Compression Algorithm Name Reference Note
none RFC 4253 Section 6.2
zlib RFC 4253 Section 6.2

SSH Public-Key File Header Tags

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4716: The Secure Shell (SSH) Public Key File Format
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Tags beginning with x- Reserved for Private Use

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Header Tag Reference Note
subject RFC 4716 Section 3.3.1
comment RFC 4716 Section 3.3.2

Publickey Subsystem Request Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4819: Secure Shell Public Key Subsystem
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Request Name Reference
version RFC 4819
add RFC 4819
remove RFC 4819
list RFC 4819
listattributes RFC 4819

Publickey Subsystem Response Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4819: Secure Shell Public Key Subsystem
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Response Name Reference
version RFC 4819
status RFC 4819
publickey RFC 4819
attribute RFC 4819

Publickey Subsystem Attributes

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 4819: Secure Shell Public Key Subsystem
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Attribute Name Reference
comment RFC 4819
comment-language RFC 4819
command-override RFC 4819
subsystem RFC 4819
x11 RFC 4819
shell RFC 4819
exec RFC 4819
agent RFC 4819
env RFC 4819
from RFC 4819
port-forward RFC 4819
reverse-forward RFC 4819

Publickey Subsystem Status Codes

Reference

  • RFC 4819: Secure Shell Public Key Subsystem

Available Formats

Range Registration Procedures
0-191 Standards Action
192-255 Reserved for Private Use
Value Status Code Reference
0 SSH_PUBLICKEY_SUCCESS RFC 4819
1 SSH_PUBLICKEY_ACCESS_DENIED RFC 4819
2 SSH_PUBLICKEY_STORAGE_EXCEEDED RFC 4819
3 SSH_PUBLICKEY_VERSION_NOT_SUPPORTED RFC 4819
4 SSH_PUBLICKEY_KEY_NOT_FOUND RFC 4819
5 SSH_PUBLICKEY_KEY_NOT_SUPPORTED RFC 4819
6 SSH_PUBLICKEY_KEY_ALREADY_PRESENT RFC 4819
7 SSH_PUBLICKEY_GENERAL_FAILURE RFC 4819
8 SSH_PUBLICKEY_REQUEST_NOT_SUPPORTED RFC 4819
9 SSH_PUBLICKEY_ATTRIBUTE_NOT_SUPPORTED RFC 4819
10-191 Standards Action
192-255 Reserved

Extension Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Peter Yee, Markus Stenberg

Reference

  • RFC 8308: Extension Negotiation in the Secure Shell (SSH) Protocol
  • RFC 9519: Update to the IANA SSH Protocol Parameters Registry Requirements

Note

Names in the Extension Names table MUST follow the Conventions for Names defined in RFC 4250, Section 4.6.1.

Note

Registration requests should be sent to the mailing list described in RFC 9519. If approved, designated experts should notify IANA within three weeks. For assistance, please contact iana@iana.org.

Available Formats

Extension Name Reference Note
server-sig-algs RFC 8308 Section 3.1
delay-compression RFC 8308 Section 3.2
no-flow-control RFC 8308 Section 3.3
elevation RFC 8308 Section 3.4
agent-forward RFC 9987 Section 7.1

SSH Agent Protocol Message Type Numbers

Expert(s)

  • Damien Miller, Markus Friedl

Reference

  • RFC 9987: Secure Shell (SSH) Agent Protocol

Available Formats

Range Registration Procedures
0-239 Expert Review
240-255 Private Use
Number Identifier Reference
0 Reserved RFC 9987, Section 8.1.1
1 Reserved RFC 9987, Section 8.1.1
2 Reserved RFC 9987, Section 8.1.1
3 Reserved RFC 9987, Section 8.1.1
4 Reserved RFC 9987, Section 8.1.1
5 SSH_AGENT_FAILURE RFC 9987, Section 5.1, 8.1
6 SSH_AGENT_SUCCESS RFC 9987, Section 5.1, 8.1
7 Reserved RFC 9987, Section 8.1.1
8 Reserved RFC 9987, Section 8.1.1
9 Reserved RFC 9987, Section 8.1.1
10 Reserved RFC 9987, Section 8.1.1
11 SSH_AGENTC_REQUEST_IDENTITIES RFC 9987, Section 5.5, 8.1
12 SSH_AGENT_IDENTITIES_ANSWER RFC 9987, Section 5.5, 8.1
13 SSH_AGENTC_SIGN_REQUEST RFC 9987, Section 5.6, 8.1
14 SSH_AGENT_SIGN_RESPONSE RFC 9987, Section 5.6, 8.1
15 Reserved RFC 9987, Section 8.1.1
16 Reserved RFC 9987, Section 8.1.1
17 SSH_AGENTC_ADD_IDENTITY RFC 9987, Section 5.2, 8.1
18 SSH_AGENTC_REMOVE_IDENTITY RFC 9987, Section 5.4, 8.1
19 SSH_AGENTC_REMOVE_ALL_IDENTITIES RFC 9987, Section 5.4, 8.1
20 SSH_AGENTC_ADD_SMARTCARD_KEY RFC 9987, Section 5.2.6, 8.1
21 SSH_AGENTC_REMOVE_SMARTCARD_KEY RFC 9987, Section 5.4, 8.1
22 SSH_AGENTC_LOCK RFC 9987, Section 5.7, 8.1
23 SSH_AGENTC_UNLOCK RFC 9987, Section 5.7, 8.1
24 Reserved RFC 9987, Section 8.1.1
25 SSH_AGENTC_ADD_ID_CONSTRAINED RFC 9987, Section 5.2, 8.1
26 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED RFC 9987, Section 5.2.6, 8.1
27 SSH_AGENTC_EXTENSION RFC 9987, Section 5.8, 8.1
28 SSH_AGENT_EXTENSION_FAILURE RFC 9987, Section 5.8, 8.1
29 SSH_AGENT_EXTENSION_RESPONSE RFC 9987, Section 5.8, 8.1
30-239 Unassigned
240-255 Reserved for Private Use RFC 9987, Section 8.1

SSH Agent Key Constraint Numbers

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Damien Miller, Markus Friedl

Reference

  • RFC 9987: Secure Shell (SSH) Agent Protocol

Available Formats

Number Identifier Reference
0 Reserved RFC 9987, Section 8.2
1 SSH_AGENT_CONSTRAIN_LIFETIME RFC 9987, Section 8.2
2 SSH_AGENT_CONSTRAIN_CONFIRM RFC 9987, Section 8.2
3-254 Unassigned
255 SSH_AGENT_CONSTRAIN_EXTENSION RFC 9987, Section 8.2

SSH Agent Key Constraint Extension Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Damien Miller, Markus Friedl

Reference

  • RFC 9987: Secure Shell (SSH) Agent Protocol
Number Identifier Reference
No registrations at this time.

SSH Agent Signature Flags

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Damien Miller, Markus Friedl

Reference

  • RFC 9987: Secure Shell (SSH) Agent Protocol

Available Formats

Number Identifier Reference
0x01 Reserved RFC 9987, Section 8.3
0x02 SSH_AGENT_RSA_SHA2_256 RFC 9987, Section 8.3
0x04 SSH_AGENT_RSA_SHA2_512 RFC 9987, Section 8.3

SSH Agent Extension Request Names

Registration Procedure(s)

  • Expert Review

Expert(s)

  • Damien Miller, Markus Friedl

Reference

  • RFC 9987: Secure Shell (SSH) Agent Protocol

Available Formats

Extension Name Reference
query RFC 9987, Section 5.8.1