Annotation of src/usr.bin/ssh/ssh.1, Revision 1.199
1.1 deraadt 1: .\" -*- nroff -*-
2: .\"
3: .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
4: .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: .\" All rights reserved
6: .\"
1.59 deraadt 7: .\" As far as I am concerned, the code I have written for this software
8: .\" can be used freely for any purpose. Any derived versions of this
9: .\" software must be clearly marked as such, and if the derived work is
10: .\" incompatible with the protocol description in the RFC file, it must be
11: .\" called by a name other than "ssh" or "Secure Shell".
12: .\"
1.93 deraadt 13: .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
14: .\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
15: .\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
1.59 deraadt 16: .\"
17: .\" Redistribution and use in source and binary forms, with or without
18: .\" modification, are permitted provided that the following conditions
19: .\" are met:
20: .\" 1. Redistributions of source code must retain the above copyright
21: .\" notice, this list of conditions and the following disclaimer.
22: .\" 2. Redistributions in binary form must reproduce the above copyright
23: .\" notice, this list of conditions and the following disclaimer in the
24: .\" documentation and/or other materials provided with the distribution.
1.1 deraadt 25: .\"
1.59 deraadt 26: .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27: .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28: .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29: .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30: .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31: .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32: .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33: .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34: .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35: .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.1 deraadt 36: .\"
1.199 ! jmc 37: .\" $OpenBSD: ssh.1,v 1.198 2004/11/07 00:01:46 djm Exp $
1.2 deraadt 38: .Dd September 25, 1999
39: .Dt SSH 1
40: .Os
41: .Sh NAME
42: .Nm ssh
1.96 deraadt 43: .Nd OpenSSH SSH client (remote login program)
1.2 deraadt 44: .Sh SYNOPSIS
45: .Nm ssh
1.191 djm 46: .Op Fl 1246AaCfgkMNnqsTtVvXxY
1.108 markus 47: .Op Fl b Ar bind_address
1.51 markus 48: .Op Fl c Ar cipher_spec
1.193 jmc 49: .Bk -words
1.176 jmc 50: .Op Fl D Ar port
1.2 deraadt 51: .Op Fl e Ar escape_char
1.176 jmc 52: .Op Fl F Ar configfile
1.2 deraadt 53: .Op Fl i Ar identity_file
1.12 aaron 54: .Oo Fl L Xo
55: .Sm off
1.33 markus 56: .Ar port :
1.12 aaron 57: .Ar host :
58: .Ar hostport
59: .Sm on
60: .Xc
61: .Oc
1.168 jmc 62: .Ek
1.176 jmc 63: .Op Fl l Ar login_name
64: .Op Fl m Ar mac_spec
1.198 djm 65: .Op Fl O Ar ctl_cmd
1.176 jmc 66: .Op Fl o Ar option
1.168 jmc 67: .Bk -words
1.176 jmc 68: .Op Fl p Ar port
69: .Ek
1.12 aaron 70: .Oo Fl R Xo
71: .Sm off
1.33 markus 72: .Ar port :
1.12 aaron 73: .Ar host :
74: .Ar hostport
75: .Sm on
76: .Xc
77: .Oc
1.198 djm 78: .Op Fl S Ar ctl_path
1.176 jmc 79: .Oo Ar user Ns @ Oc Ns Ar hostname
1.2 deraadt 80: .Op Ar command
1.44 aaron 81: .Sh DESCRIPTION
1.2 deraadt 82: .Nm
1.96 deraadt 83: (SSH client) is a program for logging into a remote machine and for
1.40 aaron 84: executing commands on a remote machine.
1.176 jmc 85: It is intended to replace rlogin and rsh,
86: and provide secure encrypted communications between
1.40 aaron 87: two untrusted hosts over an insecure network.
1.176 jmc 88: X11 connections and arbitrary TCP/IP ports
89: can also be forwarded over the secure channel.
1.2 deraadt 90: .Pp
91: .Nm
1.44 aaron 92: connects and logs into the specified
1.176 jmc 93: .Ar hostname
94: (with optional
95: .Ar user
96: name).
1.1 deraadt 97: The user must prove
1.49 markus 98: his/her identity to the remote machine using one of several methods
1.176 jmc 99: depending on the protocol version used.
1.49 markus 100: .Pp
1.176 jmc 101: If
102: .Ar command
103: is specified,
104: .Ar command
105: is executed on the remote host instead of a login shell.
1.49 markus 106: .Ss SSH protocol version 1
1.195 markus 107: The first authentication method is the
108: .Em rhosts
109: or
110: .Em hosts.equiv
111: method combined with RSA-based host authentication.
112: If the machine the user logs in from is listed in
1.2 deraadt 113: .Pa /etc/hosts.equiv
1.1 deraadt 114: or
1.2 deraadt 115: .Pa /etc/shosts.equiv
1.1 deraadt 116: on the remote machine, and the user names are
1.195 markus 117: the same on both sides, or if the files
118: .Pa $HOME/.rhosts
1.1 deraadt 119: or
1.195 markus 120: .Pa $HOME/.shosts
121: exist in the user's home directory on the
122: remote machine and contain a line containing the name of the client
1.1 deraadt 123: machine and the name of the user on that machine, the user is
1.195 markus 124: considered for log in.
125: Additionally, if the server can verify the client's
1.44 aaron 126: host key (see
1.147 deraadt 127: .Pa /etc/ssh/ssh_known_hosts
1.23 markus 128: and
129: .Pa $HOME/.ssh/known_hosts
1.1 deraadt 130: in the
1.2 deraadt 131: .Sx FILES
1.176 jmc 132: section), only then is login permitted.
1.40 aaron 133: This authentication method closes security holes due to IP
134: spoofing, DNS spoofing and routing spoofing.
135: [Note to the administrator:
1.2 deraadt 136: .Pa /etc/hosts.equiv ,
1.49 markus 137: .Pa $HOME/.rhosts ,
1.1 deraadt 138: and the rlogin/rsh protocol in general, are inherently insecure and should be
139: disabled if security is desired.]
1.2 deraadt 140: .Pp
1.195 markus 141: As a second authentication method,
1.2 deraadt 142: .Nm
1.1 deraadt 143: supports RSA based authentication.
144: The scheme is based on public-key cryptography: there are cryptosystems
145: where encryption and decryption are done using separate keys, and it
146: is not possible to derive the decryption key from the encryption key.
1.40 aaron 147: RSA is one such system.
1.44 aaron 148: The idea is that each user creates a public/private
1.40 aaron 149: key pair for authentication purposes.
150: The server knows the public key, and only the user knows the private key.
1.176 jmc 151: .Pp
1.44 aaron 152: The file
1.2 deraadt 153: .Pa $HOME/.ssh/authorized_keys
1.176 jmc 154: lists the public keys that are permitted for logging in.
1.40 aaron 155: When the user logs in, the
1.2 deraadt 156: .Nm
1.1 deraadt 157: program tells the server which key pair it would like to use for
1.40 aaron 158: authentication.
1.176 jmc 159: The server checks if this key is permitted, and if so,
160: sends the user (actually the
1.2 deraadt 161: .Nm
1.1 deraadt 162: program running on behalf of the user) a challenge, a random number,
1.40 aaron 163: encrypted by the user's public key.
1.176 jmc 164: The challenge can only be decrypted using the proper private key.
165: The user's client then decrypts the challenge using the private key,
166: proving that he/she knows the private key
167: but without disclosing it to the server.
1.2 deraadt 168: .Pp
169: .Nm
1.40 aaron 170: implements the RSA authentication protocol automatically.
171: The user creates his/her RSA key pair by running
1.2 deraadt 172: .Xr ssh-keygen 1 .
1.44 aaron 173: This stores the private key in
1.49 markus 174: .Pa $HOME/.ssh/identity
1.176 jmc 175: and stores the public key in
1.49 markus 176: .Pa $HOME/.ssh/identity.pub
1.40 aaron 177: in the user's home directory.
178: The user should then copy the
1.2 deraadt 179: .Pa identity.pub
1.44 aaron 180: to
1.49 markus 181: .Pa $HOME/.ssh/authorized_keys
1.44 aaron 182: in his/her home directory on the remote machine (the
1.2 deraadt 183: .Pa authorized_keys
1.44 aaron 184: file corresponds to the conventional
1.49 markus 185: .Pa $HOME/.rhosts
1.1 deraadt 186: file, and has one key
1.40 aaron 187: per line, though the lines can be very long).
188: After this, the user can log in without giving the password.
1.2 deraadt 189: .Pp
1.1 deraadt 190: The most convenient way to use RSA authentication may be with an
1.40 aaron 191: authentication agent.
192: See
1.2 deraadt 193: .Xr ssh-agent 1
1.1 deraadt 194: for more information.
1.2 deraadt 195: .Pp
1.44 aaron 196: If other authentication methods fail,
1.2 deraadt 197: .Nm
1.40 aaron 198: prompts the user for a password.
199: The password is sent to the remote
1.1 deraadt 200: host for checking; however, since all communications are encrypted,
201: the password cannot be seen by someone listening on the network.
1.49 markus 202: .Ss SSH protocol version 2
1.176 jmc 203: When a user connects using protocol version 2,
1.145 markus 204: similar authentication methods are available.
1.107 markus 205: Using the default values for
206: .Cm PreferredAuthentications ,
1.123 markus 207: the client will try to authenticate first using the hostbased method;
1.176 jmc 208: if this method fails, public key authentication is attempted,
209: and finally if this method fails, keyboard-interactive and
1.123 markus 210: password authentication are tried.
1.49 markus 211: .Pp
212: The public key method is similar to RSA authentication described
1.107 markus 213: in the previous section and allows the RSA or DSA algorithm to be used:
1.102 itojun 214: The client uses his private key,
1.49 markus 215: .Pa $HOME/.ssh/id_dsa
1.102 itojun 216: or
217: .Pa $HOME/.ssh/id_rsa ,
1.49 markus 218: to sign the session identifier and sends the result to the server.
219: The server checks whether the matching public key is listed in
1.115 markus 220: .Pa $HOME/.ssh/authorized_keys
1.49 markus 221: and grants access if both the key is found and the signature is correct.
222: The session identifier is derived from a shared Diffie-Hellman value
223: and is only known to the client and the server.
224: .Pp
1.176 jmc 225: If public key authentication fails or is not available, a password
226: can be sent encrypted to the remote host to prove the user's identity.
1.107 markus 227: .Pp
228: Additionally,
229: .Nm
230: supports hostbased or challenge response authentication.
1.49 markus 231: .Pp
232: Protocol 2 provides additional mechanisms for confidentiality
1.189 dtucker 233: (the traffic is encrypted using AES, 3DES, Blowfish, CAST128 or Arcfour)
234: and integrity (hmac-md5, hmac-sha1, hmac-ripemd160).
1.49 markus 235: Note that protocol 1 lacks a strong mechanism for ensuring the
236: integrity of the connection.
237: .Ss Login session and remote execution
1.1 deraadt 238: When the user's identity has been accepted by the server, the server
239: either executes the given command, or logs into the machine and gives
1.40 aaron 240: the user a normal shell on the remote machine.
241: All communication with
1.1 deraadt 242: the remote command or shell will be automatically encrypted.
1.2 deraadt 243: .Pp
1.1 deraadt 244: If a pseudo-terminal has been allocated (normal login session), the
1.104 djm 245: user may use the escape characters noted below.
1.2 deraadt 246: .Pp
1.176 jmc 247: If no pseudo-tty has been allocated,
248: the session is transparent and can be used to reliably transfer binary data.
1.40 aaron 249: On most systems, setting the escape character to
1.2 deraadt 250: .Dq none
251: will also make the session transparent even if a tty is used.
252: .Pp
1.71 djm 253: The session terminates when the command or shell on the remote
1.92 markus 254: machine exits and all X11 and TCP/IP connections have been closed.
1.176 jmc 255: The exit status of the remote program is returned as the exit status of
1.2 deraadt 256: .Nm ssh .
1.104 djm 257: .Ss Escape Characters
1.176 jmc 258: When a pseudo-terminal has been requested,
259: .Nm
260: supports a number of functions through the use of an escape character.
1.104 djm 261: .Pp
262: A single tilde character can be sent as
263: .Ic ~~
1.119 stevesk 264: or by following the tilde by a character other than those described below.
1.104 djm 265: The escape character must always follow a newline to be interpreted as
266: special.
267: The escape character can be changed in configuration files using the
268: .Cm EscapeChar
1.117 itojun 269: configuration directive or on the command line by the
1.104 djm 270: .Fl e
271: option.
272: .Pp
273: The supported escapes (assuming the default
274: .Ql ~ )
275: are:
276: .Bl -tag -width Ds
277: .It Cm ~.
1.176 jmc 278: Disconnect.
1.104 djm 279: .It Cm ~^Z
1.176 jmc 280: Background
281: .Nm ssh .
1.104 djm 282: .It Cm ~#
1.176 jmc 283: List forwarded connections.
1.104 djm 284: .It Cm ~&
1.176 jmc 285: Background
286: .Nm
287: at logout when waiting for forwarded connection / X11 sessions to terminate.
1.104 djm 288: .It Cm ~?
1.176 jmc 289: Display a list of escape characters.
1.170 markus 290: .It Cm ~B
1.176 jmc 291: Send a BREAK to the remote system
292: (only useful for SSH protocol version 2 and if the peer supports it).
1.149 jakob 293: .It Cm ~C
1.186 djm 294: Open command line.
295: Currently this allows the addition of port forwardings using the
1.149 jakob 296: .Fl L
297: and
298: .Fl R
1.186 djm 299: options (see below).
1.188 jmc 300: It also allows the cancellation of existing remote port-forwardings
1.186 djm 301: using
302: .Fl KR Ar hostport .
1.187 djm 303: Basic help is available, using the
304: .Fl h
1.186 djm 305: option.
1.104 djm 306: .It Cm ~R
1.176 jmc 307: Request rekeying of the connection
308: (only useful for SSH protocol version 2 and if the peer supports it).
1.104 djm 309: .El
1.49 markus 310: .Ss X11 and TCP forwarding
1.110 deraadt 311: If the
312: .Cm ForwardX11
313: variable is set to
314: .Dq yes
1.176 jmc 315: (or see the description of the
1.110 deraadt 316: .Fl X
317: and
318: .Fl x
319: options described later)
320: and the user is using X11 (the
1.2 deraadt 321: .Ev DISPLAY
1.1 deraadt 322: environment variable is set), the connection to the X11 display is
323: automatically forwarded to the remote side in such a way that any X11
324: programs started from the shell (or command) will go through the
325: encrypted channel, and the connection to the real X server will be made
1.40 aaron 326: from the local machine.
327: The user should not manually set
1.2 deraadt 328: .Ev DISPLAY .
1.1 deraadt 329: Forwarding of X11 connections can be
330: configured on the command line or in configuration files.
1.2 deraadt 331: .Pp
332: The
1.44 aaron 333: .Ev DISPLAY
1.2 deraadt 334: value set by
335: .Nm
1.176 jmc 336: will point to the server machine, but with a display number greater than zero.
1.40 aaron 337: This is normal, and happens because
1.2 deraadt 338: .Nm
339: creates a
340: .Dq proxy
341: X server on the server machine for forwarding the
1.1 deraadt 342: connections over the encrypted channel.
1.2 deraadt 343: .Pp
344: .Nm
1.1 deraadt 345: will also automatically set up Xauthority data on the server machine.
346: For this purpose, it will generate a random authorization cookie,
347: store it in Xauthority on the server, and verify that any forwarded
348: connections carry this cookie and replace it by the real cookie when
1.40 aaron 349: the connection is opened.
350: The real authentication cookie is never
1.1 deraadt 351: sent to the server machine (and no cookies are sent in the plain).
1.2 deraadt 352: .Pp
1.163 stevesk 353: If the
354: .Cm ForwardAgent
355: variable is set to
356: .Dq yes
1.176 jmc 357: (or see the description of the
1.163 stevesk 358: .Fl A
359: and
360: .Fl a
1.168 jmc 361: options described later) and
1.163 stevesk 362: the user is using an authentication agent, the connection to the agent
363: is automatically forwarded to the remote side.
1.2 deraadt 364: .Pp
1.1 deraadt 365: Forwarding of arbitrary TCP/IP connections over the secure channel can
1.120 stevesk 366: be specified either on the command line or in a configuration file.
1.40 aaron 367: One possible application of TCP/IP forwarding is a secure connection to an
1.92 markus 368: electronic purse; another is going through firewalls.
1.49 markus 369: .Ss Server authentication
1.2 deraadt 370: .Nm
1.49 markus 371: automatically maintains and checks a database containing
1.40 aaron 372: identifications for all hosts it has ever been used with.
1.116 markus 373: Host keys are stored in
1.49 markus 374: .Pa $HOME/.ssh/known_hosts
1.40 aaron 375: in the user's home directory.
1.116 markus 376: Additionally, the file
1.147 deraadt 377: .Pa /etc/ssh/ssh_known_hosts
1.116 markus 378: is automatically checked for known hosts.
1.40 aaron 379: Any new hosts are automatically added to the user's file.
1.176 jmc 380: If a host's identification ever changes,
1.2 deraadt 381: .Nm
1.1 deraadt 382: warns about this and disables password authentication to prevent a
1.40 aaron 383: trojan horse from getting the user's password.
1.176 jmc 384: Another purpose of this mechanism is to prevent man-in-the-middle attacks
385: which could otherwise be used to circumvent the encryption.
1.40 aaron 386: The
1.2 deraadt 387: .Cm StrictHostKeyChecking
1.158 stevesk 388: option can be used to prevent logins to machines whose
1.1 deraadt 389: host key is not known or has changed.
1.194 jakob 390: .Pp
391: .Nm
392: can be configured to verify host identification using fingerprint resource
393: records (SSHFP) published in DNS.
394: The
395: .Cm VerifyHostKeyDNS
396: option can be used to control how DNS lookups are performed.
397: SSHFP resource records can be generated using
398: .Xr ssh-keygen 1 .
1.65 aaron 399: .Pp
400: The options are as follows:
1.2 deraadt 401: .Bl -tag -width Ds
1.176 jmc 402: .It Fl 1
403: Forces
404: .Nm
405: to try protocol version 1 only.
406: .It Fl 2
407: Forces
408: .Nm
409: to try protocol version 2 only.
410: .It Fl 4
411: Forces
412: .Nm
413: to use IPv4 addresses only.
414: .It Fl 6
415: Forces
416: .Nm
417: to use IPv6 addresses only.
1.54 markus 418: .It Fl A
419: Enables forwarding of the authentication agent connection.
420: This can also be specified on a per-host basis in a configuration file.
1.165 stevesk 421: .Pp
1.168 jmc 422: Agent forwarding should be enabled with caution.
423: Users with the ability to bypass file permissions on the remote host
424: (for the agent's Unix-domain socket)
425: can access the local agent through the forwarded connection.
426: An attacker cannot obtain key material from the agent,
1.165 stevesk 427: however they can perform operations on the keys that enable them to
428: authenticate using the identities loaded into the agent.
1.176 jmc 429: .It Fl a
430: Disables forwarding of the authentication agent connection.
1.108 markus 431: .It Fl b Ar bind_address
432: Specify the interface to transmit from on machines with multiple
433: interfaces or aliased addresses.
1.176 jmc 434: .It Fl C
435: Requests compression of all data (including stdin, stdout, stderr, and
436: data for forwarded X11 and TCP/IP connections).
437: The compression algorithm is the same used by
438: .Xr gzip 1 ,
439: and the
440: .Dq level
441: can be controlled by the
442: .Cm CompressionLevel
443: option for protocol version 1.
444: Compression is desirable on modem lines and other
445: slow connections, but will only slow down things on fast networks.
446: The default value can be set on a host-by-host basis in the
447: configuration files; see the
448: .Cm Compression
449: option.
1.189 dtucker 450: .It Fl c Ar cipher_spec
451: Selects the cipher specification for encrypting the session.
452: .Pp
453: Protocol version 1 allows specification of a single cipher.
454: The suported values are
455: .Dq 3des ,
456: .Dq blowfish
457: and
458: .Dq des .
1.2 deraadt 459: .Ar 3des
1.189 dtucker 460: (triple-des) is an encrypt-decrypt-encrypt triple with three different keys.
1.44 aaron 461: It is believed to be secure.
1.5 deraadt 462: .Ar blowfish
1.176 jmc 463: is a fast block cipher; it appears very secure and is much faster than
1.40 aaron 464: .Ar 3des .
1.131 stevesk 465: .Ar des
466: is only supported in the
467: .Nm
468: client for interoperability with legacy protocol 1 implementations
469: that do not support the
470: .Ar 3des
1.168 jmc 471: cipher.
472: Its use is strongly discouraged due to cryptographic weaknesses.
1.189 dtucker 473: The default is
474: .Dq 3des .
475: .Pp
476: For protocol version 2
477: .Ar cipher_spec
478: is a comma-separated list of ciphers
479: listed in order of preference.
480: The supported ciphers are
481: .Dq 3des-cbc ,
482: .Dq aes128-cbc ,
483: .Dq aes192-cbc ,
484: .Dq aes256-cbc ,
485: .Dq aes128-ctr ,
486: .Dq aes192-ctr ,
487: .Dq aes256-ctr ,
488: .Dq arcfour ,
489: .Dq blowfish-cbc ,
490: and
491: .Dq cast128-cbc .
492: The default is
493: .Bd -literal
494: ``aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,
495: aes192-cbc,aes256-cbc''
496: .Ed
1.176 jmc 497: .It Fl D Ar port
498: Specifies a local
499: .Dq dynamic
500: application-level port forwarding.
501: This works by allocating a socket to listen to
502: .Ar port
503: on the local side, and whenever a connection is made to this port, the
504: connection is forwarded over the secure channel, and the application
505: protocol is then used to determine where to connect to from the
506: remote machine.
507: Currently the SOCKS4 and SOCKS5 protocols are supported, and
508: .Nm
509: will act as a SOCKS server.
510: Only root can forward privileged ports.
511: Dynamic port forwardings can also be specified in the configuration file.
512: .It Fl e Ar ch | ^ch | none
1.2 deraadt 513: Sets the escape character for sessions with a pty (default:
514: .Ql ~ ) .
1.40 aaron 515: The escape character is only recognized at the beginning of a line.
516: The escape character followed by a dot
1.2 deraadt 517: .Pq Ql \&.
1.176 jmc 518: closes the connection;
519: followed by control-Z suspends the connection;
520: and followed by itself sends the escape character once.
1.40 aaron 521: Setting the character to
1.2 deraadt 522: .Dq none
523: disables any escapes and makes the session fully transparent.
1.176 jmc 524: .It Fl F Ar configfile
525: Specifies an alternative per-user configuration file.
526: If a configuration file is given on the command line,
527: the system-wide configuration file
528: .Pq Pa /etc/ssh/ssh_config
529: will be ignored.
530: The default for the per-user configuration file is
531: .Pa $HOME/.ssh/config .
1.2 deraadt 532: .It Fl f
533: Requests
534: .Nm
1.40 aaron 535: to go to background just before command execution.
536: This is useful if
1.2 deraadt 537: .Nm
538: is going to ask for passwords or passphrases, but the user
1.40 aaron 539: wants it in the background.
1.44 aaron 540: This implies
1.2 deraadt 541: .Fl n .
1.1 deraadt 542: The recommended way to start X11 programs at a remote site is with
1.2 deraadt 543: something like
544: .Ic ssh -f host xterm .
1.34 markus 545: .It Fl g
546: Allows remote hosts to connect to local forwarded ports.
1.176 jmc 547: .It Fl I Ar smartcard_device
548: Specifies which smartcard device to use.
549: The argument is the device
550: .Nm
551: should use to communicate with a smartcard used for storing the user's
552: private RSA key.
1.2 deraadt 553: .It Fl i Ar identity_file
1.144 stevesk 554: Selects a file from which the identity (private key) for
1.68 markus 555: RSA or DSA authentication is read.
1.144 stevesk 556: The default is
1.49 markus 557: .Pa $HOME/.ssh/identity
1.144 stevesk 558: for protocol version 1, and
559: .Pa $HOME/.ssh/id_rsa
560: and
561: .Pa $HOME/.ssh/id_dsa
562: for protocol version 2.
1.40 aaron 563: Identity files may also be specified on
564: a per-host basis in the configuration file.
565: It is possible to have multiple
1.2 deraadt 566: .Fl i
567: options (and multiple identities specified in
1.1 deraadt 568: configuration files).
1.2 deraadt 569: .It Fl k
1.179 dtucker 570: Disables forwarding (delegation) of GSSAPI credentials to the server.
1.176 jmc 571: .It Fl L Xo
572: .Sm off
573: .Ar port : host : hostport
574: .Sm on
575: .Xc
576: Specifies that the given port on the local (client) host is to be
577: forwarded to the given host and port on the remote side.
578: This works by allocating a socket to listen to
579: .Ar port
580: on the local side, and whenever a connection is made to this port, the
581: connection is forwarded over the secure channel, and a connection is
582: made to
583: .Ar host
584: port
585: .Ar hostport
586: from the remote machine.
587: Port forwardings can also be specified in the configuration file.
588: Only root can forward privileged ports.
589: IPv6 addresses can be specified with an alternative syntax:
590: .Sm off
591: .Xo
592: .Ar port No / Ar host No /
593: .Ar hostport .
594: .Xc
595: .Sm on
1.2 deraadt 596: .It Fl l Ar login_name
1.40 aaron 597: Specifies the user to log in as on the remote machine.
598: This also may be specified on a per-host basis in the configuration file.
1.190 djm 599: .It Fl M
600: Places the
601: .Nm
602: client into
603: .Dq master
604: mode for connection sharing.
605: Refer to the description of
606: .Cm ControlMaster
607: in
608: .Xr ssh_config 5
609: for details.
1.193 jmc 610: .It Fl m Ar mac_spec
611: Additionally, for protocol version 2 a comma-separated list of MAC
612: (message authentication code) algorithms can
613: be specified in order of preference.
614: See the
615: .Cm MACs
616: keyword for more information.
1.176 jmc 617: .It Fl N
618: Do not execute a remote command.
619: This is useful for just forwarding ports
620: (protocol version 2 only).
1.2 deraadt 621: .It Fl n
622: Redirects stdin from
623: .Pa /dev/null
624: (actually, prevents reading from stdin).
1.1 deraadt 625: This must be used when
1.2 deraadt 626: .Nm
1.40 aaron 627: is run in the background.
628: A common trick is to use this to run X11 programs on a remote machine.
629: For example,
1.2 deraadt 630: .Ic ssh -n shadows.cs.hut.fi emacs &
631: will start an emacs on shadows.cs.hut.fi, and the X11
1.1 deraadt 632: connection will be automatically forwarded over an encrypted channel.
633: The
1.2 deraadt 634: .Nm
1.1 deraadt 635: program will be put in the background.
636: (This does not work if
1.2 deraadt 637: .Nm
638: needs to ask for a password or passphrase; see also the
639: .Fl f
640: option.)
1.199 ! jmc 641: .It Fl O Ar ctl_cmd
! 642: Control an active connection multiplexing master process.
! 643: When the
! 644: .Fl O
! 645: option is specified, the
! 646: .Ar ctl_cmd
! 647: argument is interpreted and passed to the master process.
! 648: Valid commands are:
! 649: .Dq check
! 650: (check that the master process is running) and
! 651: .Dq exit
! 652: (request the master to exit).
1.2 deraadt 653: .It Fl o Ar option
1.127 stevesk 654: Can be used to give options in the format used in the configuration file.
1.1 deraadt 655: This is useful for specifying options for which there is no separate
1.40 aaron 656: command-line flag.
1.176 jmc 657: For full details of the options listed below, and their possible values, see
658: .Xr ssh_config 5 .
659: .Pp
660: .Bl -tag -width Ds -offset indent -compact
661: .It AddressFamily
662: .It BatchMode
663: .It BindAddress
664: .It ChallengeResponseAuthentication
665: .It CheckHostIP
666: .It Cipher
667: .It Ciphers
668: .It ClearAllForwardings
669: .It Compression
670: .It CompressionLevel
671: .It ConnectionAttempts
1.185 dtucker 672: .It ConnectTimeout
1.190 djm 673: .It ControlMaster
674: .It ControlPath
1.176 jmc 675: .It DynamicForward
676: .It EscapeChar
677: .It ForwardAgent
678: .It ForwardX11
1.178 markus 679: .It ForwardX11Trusted
1.176 jmc 680: .It GatewayPorts
681: .It GlobalKnownHostsFile
682: .It GSSAPIAuthentication
683: .It GSSAPIDelegateCredentials
684: .It Host
685: .It HostbasedAuthentication
686: .It HostKeyAlgorithms
687: .It HostKeyAlias
688: .It HostName
689: .It IdentityFile
1.182 markus 690: .It IdentitiesOnly
1.197 djm 691: .It KbdInteractiveDevices
1.176 jmc 692: .It LocalForward
693: .It LogLevel
694: .It MACs
695: .It NoHostAuthenticationForLocalhost
696: .It NumberOfPasswordPrompts
697: .It PasswordAuthentication
698: .It Port
699: .It PreferredAuthentications
700: .It Protocol
701: .It ProxyCommand
702: .It PubkeyAuthentication
703: .It RemoteForward
704: .It RhostsRSAAuthentication
705: .It RSAAuthentication
1.184 jmc 706: .It SendEnv
1.181 markus 707: .It ServerAliveInterval
708: .It ServerAliveCountMax
1.176 jmc 709: .It SmartcardDevice
710: .It StrictHostKeyChecking
1.180 markus 711: .It TCPKeepAlive
1.176 jmc 712: .It UsePrivilegedPort
713: .It User
714: .It UserKnownHostsFile
715: .It VerifyHostKeyDNS
716: .It XAuthLocation
717: .El
1.2 deraadt 718: .It Fl p Ar port
1.40 aaron 719: Port to connect to on the remote host.
720: This can be specified on a
1.1 deraadt 721: per-host basis in the configuration file.
1.2 deraadt 722: .It Fl q
1.40 aaron 723: Quiet mode.
724: Causes all warning and diagnostic messages to be suppressed.
1.176 jmc 725: .It Fl R Xo
726: .Sm off
727: .Ar port : host : hostport
728: .Sm on
729: .Xc
730: Specifies that the given port on the remote (server) host is to be
731: forwarded to the given host and port on the local side.
732: This works by allocating a socket to listen to
733: .Ar port
734: on the remote side, and whenever a connection is made to this port, the
735: connection is forwarded over the secure channel, and a connection is
736: made to
737: .Ar host
738: port
739: .Ar hostport
740: from the local machine.
741: Port forwardings can also be specified in the configuration file.
742: Privileged ports can be forwarded only when
743: logging in as root on the remote machine.
744: IPv6 addresses can be specified with an alternative syntax:
745: .Sm off
746: .Xo
747: .Ar port No / Ar host No /
748: .Ar hostport .
749: .Xc
750: .Sm on
1.198 djm 751: .It Fl S Ar ctl_path
1.193 jmc 752: Specifies the location of a control socket for connection sharing.
1.190 djm 753: Refer to the description of
1.191 djm 754: .Cm ControlPath
755: and
1.190 djm 756: .Cm ControlMaster
757: in
758: .Xr ssh_config 5
759: for details.
1.80 djm 760: .It Fl s
1.172 jmc 761: May be used to request invocation of a subsystem on the remote system.
762: Subsystems are a feature of the SSH2 protocol which facilitate the use
1.176 jmc 763: of SSH as a secure transport for other applications (eg.\&
764: .Xr sftp 1 ) .
1.172 jmc 765: The subsystem is specified as the remote command.
1.176 jmc 766: .It Fl T
767: Disable pseudo-tty allocation.
1.2 deraadt 768: .It Fl t
1.40 aaron 769: Force pseudo-tty allocation.
1.43 brad 770: This can be used to execute arbitrary
1.40 aaron 771: screen-based programs on a remote machine, which can be very useful,
772: e.g., when implementing menu services.
1.73 markus 773: Multiple
774: .Fl t
775: options force tty allocation, even if
776: .Nm
777: has no local tty.
1.176 jmc 778: .It Fl V
779: Display the version number and exit.
1.2 deraadt 780: .It Fl v
1.40 aaron 781: Verbose mode.
782: Causes
1.2 deraadt 783: .Nm
1.40 aaron 784: to print debugging messages about its progress.
785: This is helpful in
1.1 deraadt 786: debugging connection, authentication, and configuration problems.
1.73 markus 787: Multiple
788: .Fl v
1.169 naddy 789: options increase the verbosity.
790: The maximum is 3.
1.2 deraadt 791: .It Fl X
1.1 deraadt 792: Enables X11 forwarding.
1.54 markus 793: This can also be specified on a per-host basis in a configuration file.
1.165 stevesk 794: .Pp
1.168 jmc 795: X11 forwarding should be enabled with caution.
796: Users with the ability to bypass file permissions on the remote host
797: (for the user's X authorization database)
798: can access the local X11 display through the forwarded connection.
799: An attacker may then be able to perform activities such as keystroke monitoring.
1.176 jmc 800: .It Fl x
801: Disables X11 forwarding.
1.178 markus 802: .It Fl Y
803: Enables trusted X11 forwarding.
1.2 deraadt 804: .El
805: .Sh CONFIGURATION FILES
806: .Nm
1.158 stevesk 807: may additionally obtain configuration data from
808: a per-user configuration file and a system-wide configuration file.
809: The file format and configuration options are described in
810: .Xr ssh_config 5 .
1.2 deraadt 811: .Sh ENVIRONMENT
812: .Nm
1.1 deraadt 813: will normally set the following environment variables:
1.176 jmc 814: .Bl -tag -width LOGNAME
1.2 deraadt 815: .It Ev DISPLAY
816: The
817: .Ev DISPLAY
1.40 aaron 818: variable indicates the location of the X11 server.
1.44 aaron 819: It is automatically set by
1.2 deraadt 820: .Nm
821: to point to a value of the form
822: .Dq hostname:n
823: where hostname indicates
1.176 jmc 824: the host where the shell runs, and n is an integer \*(Ge 1.
1.40 aaron 825: .Nm
826: uses this special value to forward X11 connections over the secure
827: channel.
1.107 markus 828: The user should normally not set
829: .Ev DISPLAY
830: explicitly, as that
1.1 deraadt 831: will render the X11 connection insecure (and will require the user to
832: manually copy any required authorization cookies).
1.2 deraadt 833: .It Ev HOME
1.1 deraadt 834: Set to the path of the user's home directory.
1.2 deraadt 835: .It Ev LOGNAME
836: Synonym for
1.12 aaron 837: .Ev USER ;
838: set for compatibility with systems that use this variable.
1.2 deraadt 839: .It Ev MAIL
1.129 stevesk 840: Set to the path of the user's mailbox.
1.40 aaron 841: .It Ev PATH
1.2 deraadt 842: Set to the default
843: .Ev PATH ,
844: as specified when compiling
1.12 aaron 845: .Nm ssh .
1.118 markus 846: .It Ev SSH_ASKPASS
847: If
848: .Nm
849: needs a passphrase, it will read the passphrase from the current
850: terminal if it was run from a terminal.
851: If
852: .Nm
853: does not have a terminal associated with it but
854: .Ev DISPLAY
855: and
856: .Ev SSH_ASKPASS
857: are set, it will execute the program specified by
858: .Ev SSH_ASKPASS
859: and open an X11 window to read the passphrase.
860: This is particularly useful when calling
861: .Nm
862: from a
1.196 jmc 863: .Pa .xsession
1.118 markus 864: or related script.
865: (Note that on some machines it
866: may be necessary to redirect the input from
867: .Pa /dev/null
868: to make this work.)
1.18 markus 869: .It Ev SSH_AUTH_SOCK
1.129 stevesk 870: Identifies the path of a unix-domain socket used to communicate with the
1.17 markus 871: agent.
1.166 stevesk 872: .It Ev SSH_CONNECTION
873: Identifies the client and server ends of the connection.
1.40 aaron 874: The variable contains
1.166 stevesk 875: four space-separated values: client ip-address, client port number,
876: server ip-address and server port number.
1.73 markus 877: .It Ev SSH_ORIGINAL_COMMAND
878: The variable contains the original command line if a forced command
879: is executed.
880: It can be used to extract the original arguments.
1.2 deraadt 881: .It Ev SSH_TTY
1.1 deraadt 882: This is set to the name of the tty (path to the device) associated
1.40 aaron 883: with the current shell or command.
884: If the current session has no tty,
1.1 deraadt 885: this variable is not set.
1.2 deraadt 886: .It Ev TZ
1.1 deraadt 887: The timezone variable is set to indicate the present timezone if it
1.56 deraadt 888: was set when the daemon was started (i.e., the daemon passes the value
1.1 deraadt 889: on to new connections).
1.2 deraadt 890: .It Ev USER
1.1 deraadt 891: Set to the name of the user logging in.
1.2 deraadt 892: .El
893: .Pp
1.44 aaron 894: Additionally,
1.2 deraadt 895: .Nm
1.44 aaron 896: reads
897: .Pa $HOME/.ssh/environment ,
1.2 deraadt 898: and adds lines of the format
899: .Dq VARNAME=value
1.161 marc 900: to the environment if the file exists and if users are allowed to
901: change their environment.
1.176 jmc 902: For more information, see the
1.161 marc 903: .Cm PermitUserEnvironment
1.162 stevesk 904: option in
1.161 marc 905: .Xr sshd_config 5 .
1.2 deraadt 906: .Sh FILES
1.36 markus 907: .Bl -tag -width Ds
1.116 markus 908: .It Pa $HOME/.ssh/known_hosts
1.129 stevesk 909: Records host keys for all hosts the user has logged into that are not
1.2 deraadt 910: in
1.147 deraadt 911: .Pa /etc/ssh/ssh_known_hosts .
1.2 deraadt 912: See
913: .Xr sshd 8 .
1.102 itojun 914: .It Pa $HOME/.ssh/identity, $HOME/.ssh/id_dsa, $HOME/.ssh/id_rsa
915: Contains the authentication identity of the user.
916: They are for protocol 1 RSA, protocol 2 DSA, and protocol 2 RSA, respectively.
1.48 markus 917: These files
918: contain sensitive data and should be readable by the user but not
1.15 markus 919: accessible by others (read/write/execute).
920: Note that
921: .Nm
1.48 markus 922: ignores a private key file if it is accessible by others.
1.15 markus 923: It is possible to specify a passphrase when
1.1 deraadt 924: generating the key; the passphrase will be used to encrypt the
1.8 deraadt 925: sensitive part of this file using 3DES.
1.102 itojun 926: .It Pa $HOME/.ssh/identity.pub, $HOME/.ssh/id_dsa.pub, $HOME/.ssh/id_rsa.pub
1.1 deraadt 927: Contains the public key for authentication (public part of the
1.40 aaron 928: identity file in human-readable form).
1.48 markus 929: The contents of the
930: .Pa $HOME/.ssh/identity.pub
1.176 jmc 931: file should be added to the file
1.2 deraadt 932: .Pa $HOME/.ssh/authorized_keys
933: on all machines
1.137 deraadt 934: where the user wishes to log in using protocol version 1 RSA authentication.
1.48 markus 935: The contents of the
936: .Pa $HOME/.ssh/id_dsa.pub
1.102 itojun 937: and
938: .Pa $HOME/.ssh/id_rsa.pub
1.48 markus 939: file should be added to
1.115 markus 940: .Pa $HOME/.ssh/authorized_keys
1.48 markus 941: on all machines
1.137 deraadt 942: where the user wishes to log in using protocol version 2 DSA/RSA authentication.
1.48 markus 943: These files are not
1.40 aaron 944: sensitive and can (but need not) be readable by anyone.
1.48 markus 945: These files are
1.84 markus 946: never used automatically and are not necessary; they are only provided for
1.1 deraadt 947: the convenience of the user.
1.2 deraadt 948: .It Pa $HOME/.ssh/config
1.40 aaron 949: This is the per-user configuration file.
1.158 stevesk 950: The file format and configuration options are described in
951: .Xr ssh_config 5 .
1.183 djm 952: Because of the potential for abuse, this file must have strict permissions:
953: read/write for the user, and not accessible by others.
1.2 deraadt 954: .It Pa $HOME/.ssh/authorized_keys
1.115 markus 955: Lists the public keys (RSA/DSA) that can be used for logging in as this user.
1.40 aaron 956: The format of this file is described in the
1.2 deraadt 957: .Xr sshd 8
1.40 aaron 958: manual page.
1.176 jmc 959: In the simplest form the format is the same as the
960: .Pa .pub
1.116 markus 961: identity files.
1.48 markus 962: This file is not highly sensitive, but the recommended
963: permissions are read/write for the user, and not accessible by others.
1.147 deraadt 964: .It Pa /etc/ssh/ssh_known_hosts
1.40 aaron 965: Systemwide list of known host keys.
1.116 markus 966: This file should be prepared by the
1.1 deraadt 967: system administrator to contain the public host keys of all machines in the
1.40 aaron 968: organization.
969: This file should be world-readable.
970: This file contains
1.1 deraadt 971: public keys, one per line, in the following format (fields separated
1.116 markus 972: by spaces): system name, public key and optional comment field.
1.40 aaron 973: When different names are used
1.1 deraadt 974: for the same machine, all such names should be listed, separated by
1.40 aaron 975: commas.
1.176 jmc 976: The format is described in the
1.2 deraadt 977: .Xr sshd 8
1.1 deraadt 978: manual page.
1.2 deraadt 979: .Pp
1.1 deraadt 980: The canonical system name (as returned by name servers) is used by
1.2 deraadt 981: .Xr sshd 8
1.1 deraadt 982: to verify the client host when logging in; other names are needed because
1.2 deraadt 983: .Nm
1.1 deraadt 984: does not convert the user-supplied name to a canonical name before
985: checking the key, because someone with access to the name servers
986: would then be able to fool host authentication.
1.147 deraadt 987: .It Pa /etc/ssh/ssh_config
1.40 aaron 988: Systemwide configuration file.
1.158 stevesk 989: The file format and configuration options are described in
990: .Xr ssh_config 5 .
1.147 deraadt 991: .It Pa /etc/ssh/ssh_host_key, /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_rsa_key
1.141 markus 992: These three files contain the private parts of the host keys
993: and are used for
994: .Cm RhostsRSAAuthentication
995: and
996: .Cm HostbasedAuthentication .
1.155 stevesk 997: If the protocol version 1
998: .Cm RhostsRSAAuthentication
1.157 deraadt 999: method is used,
1.155 stevesk 1000: .Nm
1001: must be setuid root, since the host key is readable only by root.
1002: For protocol version 2,
1003: .Nm
1004: uses
1005: .Xr ssh-keysign 8
1006: to access the host keys for
1007: .Cm HostbasedAuthentication .
1008: This eliminates the requirement that
1009: .Nm
1010: be setuid root when that authentication method is used.
1011: By default
1.141 markus 1012: .Nm
1.155 stevesk 1013: is not setuid root.
1.2 deraadt 1014: .It Pa $HOME/.rhosts
1015: This file is used in
1.195 markus 1016: .Cm RhostsRSAAuthentication
1017: and
1018: .Cm HostbasedAuthentication
1.2 deraadt 1019: authentication to list the
1.40 aaron 1020: host/user pairs that are permitted to log in.
1021: (Note that this file is
1.1 deraadt 1022: also used by rlogin and rsh, which makes using this file insecure.)
1023: Each line of the file contains a host name (in the canonical form
1024: returned by name servers), and then a user name on that host,
1.40 aaron 1025: separated by a space.
1.92 markus 1026: On some machines this file may need to be
1.1 deraadt 1027: world-readable if the user's home directory is on a NFS partition,
1028: because
1.2 deraadt 1029: .Xr sshd 8
1.40 aaron 1030: reads it as root.
1031: Additionally, this file must be owned by the user,
1032: and must not have write permissions for anyone else.
1033: The recommended
1.1 deraadt 1034: permission for most machines is read/write for the user, and not
1035: accessible by others.
1.2 deraadt 1036: .Pp
1.195 markus 1037: Note that
1.2 deraadt 1038: .Xr sshd 8
1.195 markus 1039: allows authentication only in combination with client host key
1040: authentication before permitting log in.
1.137 deraadt 1041: If the server machine does not have the client's host key in
1.147 deraadt 1042: .Pa /etc/ssh/ssh_known_hosts ,
1.137 deraadt 1043: it can be stored in
1.2 deraadt 1044: .Pa $HOME/.ssh/known_hosts .
1045: The easiest way to do this is to
1.1 deraadt 1046: connect back to the client from the server machine using ssh; this
1.48 markus 1047: will automatically add the host key to
1.2 deraadt 1048: .Pa $HOME/.ssh/known_hosts .
1049: .It Pa $HOME/.shosts
1050: This file is used exactly the same way as
1.176 jmc 1051: .Pa .rhosts .
1.2 deraadt 1052: The purpose for
1.195 markus 1053: having this file is to be able to use
1054: .Cm RhostsRSAAuthentication
1055: and
1056: .Cm HostbasedAuthentication
1057: authentication without permitting login with
1.176 jmc 1058: .Xr rlogin
1.2 deraadt 1059: or
1060: .Xr rsh 1 .
1061: .It Pa /etc/hosts.equiv
1062: This file is used during
1.195 markus 1063: .Cm RhostsRSAAuthentication
1064: and
1065: .Cm HostbasedAuthentication
1.173 jmc 1066: authentication.
1.40 aaron 1067: It contains
1.176 jmc 1068: canonical hosts names, one per line (the full format is described in the
1.2 deraadt 1069: .Xr sshd 8
1.40 aaron 1070: manual page).
1071: If the client host is found in this file, login is
1.1 deraadt 1072: automatically permitted provided client and server user names are the
1.40 aaron 1073: same.
1.195 markus 1074: Additionally, successful client host key authentication is required.
1.40 aaron 1075: This file should only be writable by root.
1.2 deraadt 1076: .It Pa /etc/shosts.equiv
1.44 aaron 1077: This file is processed exactly as
1.2 deraadt 1078: .Pa /etc/hosts.equiv .
1.1 deraadt 1079: This file may be useful to permit logins using
1.2 deraadt 1080: .Nm
1.1 deraadt 1081: but not using rsh/rlogin.
1.147 deraadt 1082: .It Pa /etc/ssh/sshrc
1.1 deraadt 1083: Commands in this file are executed by
1.2 deraadt 1084: .Nm
1.1 deraadt 1085: when the user logs in just before the user's shell (or command) is started.
1086: See the
1.2 deraadt 1087: .Xr sshd 8
1.1 deraadt 1088: manual page for more information.
1.2 deraadt 1089: .It Pa $HOME/.ssh/rc
1.1 deraadt 1090: Commands in this file are executed by
1.2 deraadt 1091: .Nm
1.1 deraadt 1092: when the user logs in just before the user's shell (or command) is
1093: started.
1.44 aaron 1094: See the
1.2 deraadt 1095: .Xr sshd 8
1.1 deraadt 1096: manual page for more information.
1.31 markus 1097: .It Pa $HOME/.ssh/environment
1098: Contains additional definitions for environment variables, see section
1099: .Sx ENVIRONMENT
1100: above.
1.58 itojun 1101: .El
1.145 markus 1102: .Sh DIAGNOSTICS
1103: .Nm
1104: exits with the exit status of the remote command or with 255
1105: if an error occurred.
1.2 deraadt 1106: .Sh SEE ALSO
1.176 jmc 1107: .Xr gzip 1 ,
1.2 deraadt 1108: .Xr rsh 1 ,
1109: .Xr scp 1 ,
1.83 djm 1110: .Xr sftp 1 ,
1.2 deraadt 1111: .Xr ssh-add 1 ,
1112: .Xr ssh-agent 1 ,
1113: .Xr ssh-keygen 1 ,
1114: .Xr telnet 1 ,
1.176 jmc 1115: .Xr hosts.equiv 5 ,
1.159 stevesk 1116: .Xr ssh_config 5 ,
1.160 naddy 1117: .Xr ssh-keysign 8 ,
1.87 itojun 1118: .Xr sshd 8
1.106 markus 1119: .Rs
1120: .%A T. Ylonen
1121: .%A T. Kivinen
1122: .%A M. Saarinen
1123: .%A T. Rinne
1124: .%A S. Lehtinen
1125: .%T "SSH Protocol Architecture"
1.150 markus 1126: .%N draft-ietf-secsh-architecture-12.txt
1127: .%D January 2002
1.106 markus 1128: .%O work in progress material
1129: .Re
1.173 jmc 1130: .Sh AUTHORS
1131: OpenSSH is a derivative of the original and free
1132: ssh 1.2.12 release by Tatu Ylonen.
1133: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1134: Theo de Raadt and Dug Song
1135: removed many bugs, re-added newer features and
1136: created OpenSSH.
1137: Markus Friedl contributed the support for SSH
1138: protocol versions 1.5 and 2.0.
![[BACK]](/icons/back.gif){kind=icon}
Return to ssh.1 CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh