Annotation of src/usr.bin/ssh/sshd.8, Revision 1.74
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: .\"
1.64 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: .\"
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.
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: .\"
1.64 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: .\"
1.74 ! markus 37: .\" $OpenBSD: sshd.8,v 1.73 2000/11/22 15:38:30 provos Exp $
1.2 deraadt 38: .Dd September 25, 1999
39: .Dt SSHD 8
40: .Os
41: .Sh NAME
42: .Nm sshd
43: .Nd secure shell daemon
44: .Sh SYNOPSIS
45: .Nm sshd
1.74 ! markus 46: .Op Fl diqDQ46
1.2 deraadt 47: .Op Fl b Ar bits
48: .Op Fl f Ar config_file
49: .Op Fl g Ar login_grace_time
50: .Op Fl h Ar host_key_file
51: .Op Fl k Ar key_gen_time
52: .Op Fl p Ar port
1.61 markus 53: .Op Fl u Ar len
1.26 markus 54: .Op Fl V Ar client_protocol_id
1.40 aaron 55: .Sh DESCRIPTION
1.2 deraadt 56: .Nm
1.40 aaron 57: (Secure Shell Daemon) is the daemon program for
1.2 deraadt 58: .Xr ssh 1 .
1.42 hugh 59: Together these programs replace rlogin and rsh, and
1.1 deraadt 60: provide secure encrypted communications between two untrusted hosts
1.36 aaron 61: over an insecure network.
62: The programs are intended to be as easy to
1.1 deraadt 63: install and use as possible.
1.2 deraadt 64: .Pp
65: .Nm
1.36 aaron 66: is the daemon that listens for connections from clients.
1.40 aaron 67: It is normally started at boot from
1.2 deraadt 68: .Pa /etc/rc .
69: It forks a new
1.36 aaron 70: daemon for each incoming connection.
71: The forked daemons handle
1.1 deraadt 72: key exchange, encryption, authentication, command execution,
73: and data exchange.
1.49 markus 74: This implementation of
75: .Nm
76: supports both SSH protocol version 1 and 2 simultaneously.
1.2 deraadt 77: .Nm
1.36 aaron 78: works as follows.
1.49 markus 79: .Pp
80: .Ss SSH protocol version 1
81: .Pp
1.36 aaron 82: Each host has a host-specific RSA key
83: (normally 1024 bits) used to identify the host.
84: Additionally, when
1.1 deraadt 85: the daemon starts, it generates a server RSA key (normally 768 bits).
86: This key is normally regenerated every hour if it has been used, and
87: is never stored on disk.
1.2 deraadt 88: .Pp
1.42 hugh 89: Whenever a client connects the daemon responds with its public
90: host and server keys.
1.36 aaron 91: The client compares the
1.49 markus 92: RSA host key against its own database to verify that it has not changed.
1.36 aaron 93: The client then generates a 256 bit random number.
94: It encrypts this
1.1 deraadt 95: random number using both the host key and the server key, and sends
1.36 aaron 96: the encrypted number to the server.
1.42 hugh 97: Both sides then use this
1.1 deraadt 98: random number as a session key which is used to encrypt all further
1.36 aaron 99: communications in the session.
100: The rest of the session is encrypted
1.42 hugh 101: using a conventional cipher, currently Blowfish or 3DES, with 3DES
1.39 deraadt 102: being used by default.
1.36 aaron 103: The client selects the encryption algorithm
1.5 deraadt 104: to use from those offered by the server.
1.2 deraadt 105: .Pp
1.36 aaron 106: Next, the server and the client enter an authentication dialog.
107: The client tries to authenticate itself using
1.2 deraadt 108: .Pa .rhosts
109: authentication,
110: .Pa .rhosts
111: authentication combined with RSA host
1.1 deraadt 112: authentication, RSA challenge-response authentication, or password
113: based authentication.
1.2 deraadt 114: .Pp
1.1 deraadt 115: Rhosts authentication is normally disabled
116: because it is fundamentally insecure, but can be enabled in the server
1.36 aaron 117: configuration file if desired.
118: System security is not improved unless
1.2 deraadt 119: .Xr rshd 8 ,
120: .Xr rlogind 8 ,
121: .Xr rexecd 8 ,
122: and
123: .Xr rexd 8
1.1 deraadt 124: are disabled (thus completely disabling
1.2 deraadt 125: .Xr rlogin 1
1.1 deraadt 126: and
1.2 deraadt 127: .Xr rsh 1
1.42 hugh 128: into the machine).
1.2 deraadt 129: .Pp
1.49 markus 130: .Ss SSH protocol version 2
131: .Pp
1.58 deraadt 132: Version 2 works similarly:
1.49 markus 133: Each host has a host-specific DSA key used to identify the host.
134: However, when the daemon starts, it does not generate a server key.
135: Forward security is provided through a Diffie-Hellman key agreement.
136: This key agreement results in a shared session key.
137: The rest of the session is encrypted
138: using a symmetric cipher, currently
139: Blowfish, 3DES or CAST128 in CBC mode or Arcfour.
140: The client selects the encryption algorithm
141: to use from those offered by the server.
142: Additionally, session integrity is provided
1.51 hugh 143: through a cryptographic message authentication code
1.49 markus 144: (hmac-sha1 or hmac-md5).
145: .Pp
146: Protocol version 2 provides a public key based
1.72 markus 147: user authentication method (PubkeyAuthentication)
1.49 markus 148: and conventional password authentication.
149: .Pp
150: .Ss Command execution and data forwarding
151: .Pp
1.1 deraadt 152: If the client successfully authenticates itself, a dialog for
1.36 aaron 153: preparing the session is entered.
154: At this time the client may request
1.1 deraadt 155: things like allocating a pseudo-tty, forwarding X11 connections,
156: forwarding TCP/IP connections, or forwarding the authentication agent
157: connection over the secure channel.
1.2 deraadt 158: .Pp
1.1 deraadt 159: Finally, the client either requests a shell or execution of a command.
1.36 aaron 160: The sides then enter session mode.
161: In this mode, either side may send
1.1 deraadt 162: data at any time, and such data is forwarded to/from the shell or
163: command on the server side, and the user terminal in the client side.
1.2 deraadt 164: .Pp
1.1 deraadt 165: When the user program terminates and all forwarded X11 and other
166: connections have been closed, the server sends command exit status to
167: the client, and both sides exit.
1.2 deraadt 168: .Pp
169: .Nm
1.1 deraadt 170: can be configured using command-line options or a configuration
1.36 aaron 171: file.
172: Command-line options override values specified in the
1.1 deraadt 173: configuration file.
1.25 markus 174: .Pp
175: .Nm
176: rereads its configuration file when it receives a hangup signal,
177: .Dv SIGHUP .
1.18 aaron 178: .Pp
179: The options are as follows:
1.2 deraadt 180: .Bl -tag -width Ds
181: .It Fl b Ar bits
1.1 deraadt 182: Specifies the number of bits in the server key (default 768).
1.2 deraadt 183: .Pp
184: .It Fl d
1.36 aaron 185: Debug mode.
186: The server sends verbose debug output to the system
187: log, and does not put itself in the background.
188: The server also will not fork and will only process one connection.
189: This option is only intended for debugging for the server.
1.67 aaron 190: Multiple -d options increases the debugging level.
191: Maximum is 3.
1.2 deraadt 192: .It Fl f Ar configuration_file
1.36 aaron 193: Specifies the name of the configuration file.
194: The default is
1.2 deraadt 195: .Pa /etc/sshd_config .
1.16 markus 196: .Nm
197: refuses to start if there is no configuration file.
1.2 deraadt 198: .It Fl g Ar login_grace_time
1.1 deraadt 199: Gives the grace time for clients to authenticate themselves (default
1.36 aaron 200: 300 seconds).
201: If the client fails to authenticate the user within
202: this many seconds, the server disconnects and exits.
203: A value of zero indicates no limit.
1.2 deraadt 204: .It Fl h Ar host_key_file
1.49 markus 205: Specifies the file from which the RSA host key is read (default
1.2 deraadt 206: .Pa /etc/ssh_host_key ) .
1.7 markus 207: This option must be given if
208: .Nm
209: is not run as root (as the normal
1.1 deraadt 210: host file is normally not readable by anyone but root).
1.2 deraadt 211: .It Fl i
1.7 markus 212: Specifies that
213: .Nm
1.40 aaron 214: is being run from inetd.
1.7 markus 215: .Nm
216: is normally not run
1.1 deraadt 217: from inetd because it needs to generate the server key before it can
1.36 aaron 218: respond to the client, and this may take tens of seconds.
219: Clients would have to wait too long if the key was regenerated every time.
1.35 aaron 220: However, with small key sizes (e.g., 512) using
1.7 markus 221: .Nm
222: from inetd may
1.1 deraadt 223: be feasible.
1.2 deraadt 224: .It Fl k Ar key_gen_time
1.1 deraadt 225: Specifies how often the server key is regenerated (default 3600
1.36 aaron 226: seconds, or one hour).
227: The motivation for regenerating the key fairly
1.1 deraadt 228: often is that the key is not stored anywhere, and after about an hour,
229: it becomes impossible to recover the key for decrypting intercepted
230: communications even if the machine is cracked into or physically
1.36 aaron 231: seized.
232: A value of zero indicates that the key will never be regenerated.
1.2 deraadt 233: .It Fl p Ar port
1.1 deraadt 234: Specifies the port on which the server listens for connections
235: (default 22).
1.2 deraadt 236: .It Fl q
1.36 aaron 237: Quiet mode.
238: Nothing is sent to the system log.
239: Normally the beginning,
1.1 deraadt 240: authentication, and termination of each connection is logged.
1.61 markus 241: .It Fl u Ar len
242: This option is used to specify the size of the field
243: in the
244: .Li utmp
245: structure that holds the remote host name.
246: If the resolved host name is longer than
247: .Ar len ,
248: the dotted decimal value will be used instead.
249: This allows hosts with very long host names that
250: overflow this field to still be uniquely identified.
251: Specifying
252: .Fl u0
253: indicates that only dotted decimal addresses
254: should be put into the
255: .Pa utmp
256: file.
1.74 ! markus 257: .It Fl D
! 258: When this option is specified
! 259: .Nm
! 260: will not detach and does not become a daemon.
! 261: This allows easy monitoring of
! 262: .Nm .
1.18 aaron 263: .It Fl Q
264: Do not print an error message if RSA support is missing.
1.26 markus 265: .It Fl V Ar client_protocol_id
1.68 markus 266: SSH-2 compatibility mode.
1.42 hugh 267: When this option is specified
1.26 markus 268: .Nm
1.42 hugh 269: assumes the client has sent the supplied version string
1.26 markus 270: and skips the
271: Protocol Version Identification Exchange.
1.68 markus 272: This option is not intended to be called directly.
1.29 markus 273: .It Fl 4
274: Forces
275: .Nm
276: to use IPv4 addresses only.
277: .It Fl 6
278: Forces
279: .Nm
280: to use IPv6 addresses only.
1.2 deraadt 281: .El
282: .Sh CONFIGURATION FILE
283: .Nm
1.40 aaron 284: reads configuration data from
1.2 deraadt 285: .Pa /etc/sshd_config
286: (or the file specified with
287: .Fl f
1.36 aaron 288: on the command line).
289: The file contains keyword-value pairs, one per line.
290: Lines starting with
1.2 deraadt 291: .Ql #
1.1 deraadt 292: and empty lines are interpreted as comments.
1.2 deraadt 293: .Pp
1.1 deraadt 294: The following keywords are possible.
1.2 deraadt 295: .Bl -tag -width Ds
296: .It Cm AFSTokenPassing
1.36 aaron 297: Specifies whether an AFS token may be forwarded to the server.
298: Default is
1.2 deraadt 299: .Dq yes .
1.11 markus 300: .It Cm AllowGroups
301: This keyword can be followed by a number of group names, separated
1.36 aaron 302: by spaces.
303: If specified, login is allowed only for users whose primary
1.11 markus 304: group matches one of the patterns.
305: .Ql \&*
306: and
307: .Ql ?
308: can be used as
1.36 aaron 309: wildcards in the patterns.
1.58 deraadt 310: Only group names are valid; a numerical group ID isn't recognized.
1.36 aaron 311: By default login is allowed regardless of the primary group.
1.3 dugsong 312: .Pp
1.69 markus 313: .It Cm AllowTcpForwarding
314: Specifies whether TCP forwarding is permitted.
315: The default is
316: .Dq yes .
317: Note that disabling TCP forwarding does not improve security unless
318: users are also denied shell access, as they can always install their
319: own forwarders.
320: .Pp
1.11 markus 321: .It Cm AllowUsers
322: This keyword can be followed by a number of user names, separated
1.36 aaron 323: by spaces.
324: If specified, login is allowed only for users names that
1.11 markus 325: match one of the patterns.
326: .Ql \&*
327: and
328: .Ql ?
329: can be used as
1.36 aaron 330: wildcards in the patterns.
1.58 deraadt 331: Only user names are valid; a numerical user ID isn't recognized.
1.36 aaron 332: By default login is allowed regardless of the user name.
1.11 markus 333: .Pp
1.41 markus 334: .It Cm Ciphers
335: Specifies the ciphers allowed for protocol version 2.
336: Multiple ciphers must be comma-separated.
337: The default is
1.50 markus 338: .Dq 3des-cbc,blowfish-cbc,arcfour,cast128-cbc .
1.8 markus 339: .It Cm CheckMail
340: Specifies whether
341: .Nm
342: should check for new mail for interactive logins.
343: The default is
344: .Dq no .
1.11 markus 345: .It Cm DenyGroups
346: This keyword can be followed by a number of group names, separated
1.36 aaron 347: by spaces.
348: Users whose primary group matches one of the patterns
1.11 markus 349: aren't allowed to log in.
350: .Ql \&*
351: and
352: .Ql ?
353: can be used as
1.36 aaron 354: wildcards in the patterns.
1.58 deraadt 355: Only group names are valid; a numerical group ID isn't recognized.
1.36 aaron 356: By default login is allowed regardless of the primary group.
1.11 markus 357: .Pp
358: .It Cm DenyUsers
359: This keyword can be followed by a number of user names, separated
1.36 aaron 360: by spaces.
361: Login is disallowed for user names that match one of the patterns.
1.11 markus 362: .Ql \&*
363: and
364: .Ql ?
1.36 aaron 365: can be used as wildcards in the patterns.
1.58 deraadt 366: Only user names are valid; a numerical user ID isn't recognized.
1.36 aaron 367: By default login is allowed regardless of the user name.
1.72 markus 368: .It Cm PubkeyAuthentication
369: Specifies whether public key authentication is allowed.
1.49 markus 370: The default is
371: .Dq yes .
372: Note that this option applies to protocol version 2 only.
1.47 markus 373: .It Cm GatewayPorts
374: Specifies whether remote hosts are allowed to connect to ports
375: forwarded for the client.
376: The argument must be
377: .Dq yes
378: or
379: .Dq no .
380: The default is
381: .Dq no .
1.2 deraadt 382: .It Cm HostKey
1.72 markus 383: Specifies the file containing the private host keys (default
1.46 markus 384: .Pa /etc/ssh_host_key )
1.72 markus 385: used by SSH protocol versions 1 and 2.
1.9 markus 386: Note that
387: .Nm
1.72 markus 388: if this file is group/world-accessible.
389: It is possible to have multiple host key files.
390: .Dq rsa1
391: keys are used for version 1 and
392: .Dq dsa
393: or
394: .Dq rsa
395: are used for version 2 of the SSH protocol.
1.2 deraadt 396: .It Cm IgnoreRhosts
1.34 markus 397: Specifies that
398: .Pa .rhosts
1.40 aaron 399: and
1.34 markus 400: .Pa .shosts
401: files will not be used in authentication.
1.2 deraadt 402: .Pa /etc/hosts.equiv
1.1 deraadt 403: and
1.40 aaron 404: .Pa /etc/shosts.equiv
1.36 aaron 405: are still used.
1.40 aaron 406: The default is
1.34 markus 407: .Dq yes .
1.24 markus 408: .It Cm IgnoreUserKnownHosts
409: Specifies whether
410: .Nm
411: should ignore the user's
412: .Pa $HOME/.ssh/known_hosts
1.45 markus 413: during
1.24 markus 414: .Cm RhostsRSAAuthentication .
415: The default is
1.2 deraadt 416: .Dq no .
417: .It Cm KeepAlive
1.1 deraadt 418: Specifies whether the system should send keepalive messages to the
1.36 aaron 419: other side.
420: If they are sent, death of the connection or crash of one
421: of the machines will be properly noticed.
422: However, this means that
1.1 deraadt 423: connections will die if the route is down temporarily, and some people
1.36 aaron 424: find it annoying.
1.51 hugh 425: On the other hand, if keepalives are not sent,
1.2 deraadt 426: sessions may hang indefinitely on the server, leaving
427: .Dq ghost
428: users and consuming server resources.
429: .Pp
430: The default is
431: .Dq yes
432: (to send keepalives), and the server will notice
1.36 aaron 433: if the network goes down or the client host reboots.
434: This avoids infinitely hanging sessions.
1.2 deraadt 435: .Pp
436: To disable keepalives, the value should be set to
437: .Dq no
438: in both the server and the client configuration files.
439: .It Cm KerberosAuthentication
1.36 aaron 440: Specifies whether Kerberos authentication is allowed.
441: This can be in the form of a Kerberos ticket, or if
1.7 markus 442: .Cm PasswordAuthentication
1.1 deraadt 443: is yes, the password provided by the user will be validated through
1.67 aaron 444: the Kerberos KDC.
445: To use this option, the server needs a
1.59 provos 446: Kerberos servtab which allows the verification of the KDC's identity.
1.36 aaron 447: Default is
1.60 provos 448: .Dq yes .
1.2 deraadt 449: .It Cm KerberosOrLocalPasswd
1.1 deraadt 450: If set then if password authentication through Kerberos fails then
451: the password will be validated via any additional local mechanism
1.2 deraadt 452: such as
1.66 markus 453: .Pa /etc/passwd .
1.36 aaron 454: Default is
1.20 dugsong 455: .Dq yes .
1.2 deraadt 456: .It Cm KerberosTgtPassing
1.1 deraadt 457: Specifies whether a Kerberos TGT may be forwarded to the server.
1.40 aaron 458: Default is
1.3 dugsong 459: .Dq no ,
460: as this only works when the Kerberos KDC is actually an AFS kaserver.
1.2 deraadt 461: .It Cm KerberosTicketCleanup
1.7 markus 462: Specifies whether to automatically destroy the user's ticket cache
1.36 aaron 463: file on logout.
464: Default is
1.3 dugsong 465: .Dq yes .
1.2 deraadt 466: .It Cm KeyRegenerationInterval
1.1 deraadt 467: The server key is automatically regenerated after this many seconds
1.36 aaron 468: (if it has been used).
469: The purpose of regeneration is to prevent
1.1 deraadt 470: decrypting captured sessions by later breaking into the machine and
1.36 aaron 471: stealing the keys.
472: The key is never stored anywhere.
473: If the value is 0, the key is never regenerated.
474: The default is 3600 (seconds).
1.7 markus 475: .It Cm ListenAddress
476: Specifies what local address
477: .Nm
478: should listen on.
479: The default is to listen to all local addresses.
1.28 markus 480: Multiple options of this type are permitted.
481: Additionally, the
482: .Cm Ports
483: options must precede this option.
1.2 deraadt 484: .It Cm LoginGraceTime
1.1 deraadt 485: The server disconnects after this time if the user has not
1.36 aaron 486: successfully logged in.
487: If the value is 0, there is no time limit.
1.1 deraadt 488: The default is 600 (seconds).
1.23 markus 489: .It Cm LogLevel
490: Gives the verbosity level that is used when logging messages from
491: .Nm sshd .
492: The possible values are:
1.27 markus 493: QUIET, FATAL, ERROR, INFO, VERBOSE and DEBUG.
1.23 markus 494: The default is INFO.
495: Logging with level DEBUG violates the privacy of users
496: and is not recommended.
1.55 markus 497: .It Cm MaxStartups
498: Specifies the maximum number of concurrent unauthenticated connections to the
499: .Nm
500: daemon.
501: Additional connections will be dropped until authentication succeeds or the
502: .Cm LoginGraceTime
503: expires for a connection.
504: The default is 10.
1.57 markus 505: .Pp
506: Alternatively, random early drop can be enabled by specifying
507: the three colon separated values
508: .Dq start:rate:full
1.67 aaron 509: (e.g., "10:30:60").
1.57 markus 510: .Nm
511: will refuse connection attempts with a probabillity of
512: .Dq rate/100
513: (30%)
514: if there are currently
515: .Dq start
516: (10)
517: unauthenticated connections.
518: The probabillity increases linearly and all connection attempts
519: are refused if the number of unauthenticated connections reaches
520: .Dq full
521: (60).
1.2 deraadt 522: .It Cm PasswordAuthentication
1.1 deraadt 523: Specifies whether password authentication is allowed.
1.2 deraadt 524: The default is
525: .Dq yes .
1.58 deraadt 526: Note that this option applies to both protocol versions 1 and 2.
1.2 deraadt 527: .It Cm PermitEmptyPasswords
1.1 deraadt 528: When password authentication is allowed, it specifies whether the
1.36 aaron 529: server allows login to accounts with empty password strings.
530: The default is
1.34 markus 531: .Dq no .
1.2 deraadt 532: .It Cm PermitRootLogin
1.1 deraadt 533: Specifies whether the root can log in using
1.2 deraadt 534: .Xr ssh 1 .
1.15 markus 535: The argument must be
536: .Dq yes ,
537: .Dq without-password
538: or
539: .Dq no .
1.2 deraadt 540: The default is
541: .Dq yes .
1.15 markus 542: If this options is set to
543: .Dq without-password
544: only password authentication is disabled for root.
1.2 deraadt 545: .Pp
546: Root login with RSA authentication when the
547: .Ar command
548: option has been
1.1 deraadt 549: specified will be allowed regardless of the value of this setting
550: (which may be useful for taking remote backups even if root login is
551: normally not allowed).
1.43 markus 552: .It Cm PidFile
553: Specifies the file that contains the process identifier of the
554: .Nm
555: daemon.
556: The default is
557: .Pa /var/run/sshd.pid .
1.2 deraadt 558: .It Cm Port
1.1 deraadt 559: Specifies the port number that
1.2 deraadt 560: .Nm
1.36 aaron 561: listens on.
562: The default is 22.
1.28 markus 563: Multiple options of this type are permitted.
1.2 deraadt 564: .It Cm PrintMotd
1.1 deraadt 565: Specifies whether
1.2 deraadt 566: .Nm
1.40 aaron 567: should print
1.2 deraadt 568: .Pa /etc/motd
1.36 aaron 569: when a user logs in interactively.
570: (On some systems it is also printed by the shell,
1.2 deraadt 571: .Pa /etc/profile ,
1.36 aaron 572: or equivalent.)
573: The default is
1.2 deraadt 574: .Dq yes .
1.41 markus 575: .It Cm Protocol
576: Specifies the protocol versions
577: .Nm
578: should support.
579: The possible values are
580: .Dq 1
581: and
582: .Dq 2 .
583: Multiple versions must be comma-separated.
584: The default is
585: .Dq 1 .
1.2 deraadt 586: .It Cm RandomSeed
1.36 aaron 587: Obsolete.
588: Random number generation uses other techniques.
1.2 deraadt 589: .It Cm RhostsAuthentication
1.1 deraadt 590: Specifies whether authentication using rhosts or /etc/hosts.equiv
1.36 aaron 591: files is sufficient.
592: Normally, this method should not be permitted because it is insecure.
1.7 markus 593: .Cm RhostsRSAAuthentication
594: should be used
1.1 deraadt 595: instead, because it performs RSA-based host authentication in addition
596: to normal rhosts or /etc/hosts.equiv authentication.
1.2 deraadt 597: The default is
598: .Dq no .
599: .It Cm RhostsRSAAuthentication
1.1 deraadt 600: Specifies whether rhosts or /etc/hosts.equiv authentication together
1.36 aaron 601: with successful RSA host authentication is allowed.
602: The default is
1.34 markus 603: .Dq no .
1.2 deraadt 604: .It Cm RSAAuthentication
1.36 aaron 605: Specifies whether pure RSA authentication is allowed.
606: The default is
1.2 deraadt 607: .Dq yes .
1.49 markus 608: Note that this option applies to protocol version 1 only.
1.2 deraadt 609: .It Cm ServerKeyBits
1.36 aaron 610: Defines the number of bits in the server key.
611: The minimum value is 512, and the default is 768.
1.7 markus 612: .It Cm SkeyAuthentication
613: Specifies whether
1.40 aaron 614: .Xr skey 1
1.36 aaron 615: authentication is allowed.
616: The default is
1.7 markus 617: .Dq yes .
618: Note that s/key authentication is enabled only if
619: .Cm PasswordAuthentication
620: is allowed, too.
1.2 deraadt 621: .It Cm StrictModes
1.12 markus 622: Specifies whether
623: .Nm
624: should check file modes and ownership of the
1.36 aaron 625: user's files and home directory before accepting login.
626: This is normally desirable because novices sometimes accidentally leave their
627: directory or files world-writable.
628: The default is
1.7 markus 629: .Dq yes .
1.54 jakob 630: .It Cm Subsystem
1.67 aaron 631: Configures an external subsystem (e.g., file transfer daemon).
632: Arguments should be a subsystem name and a command to execute upon subsystem
633: request.
1.63 markus 634: The command
635: .Xr sftp-server 8
636: implements the
637: .Dq sftp
638: file transfer subsystem.
1.54 jakob 639: By default no subsystems are defined.
640: Note that this option applies to protocol version 2 only.
1.2 deraadt 641: .It Cm SyslogFacility
1.1 deraadt 642: Gives the facility code that is used when logging messages from
1.2 deraadt 643: .Nm sshd .
1.1 deraadt 644: The possible values are: DAEMON, USER, AUTH, LOCAL0, LOCAL1, LOCAL2,
1.36 aaron 645: LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7.
646: The default is AUTH.
1.10 markus 647: .It Cm UseLogin
648: Specifies whether
649: .Xr login 1
1.53 markus 650: is used for interactive login sessions.
651: Note that
652: .Xr login 1
1.58 deraadt 653: is never used for remote command execution.
1.36 aaron 654: The default is
1.10 markus 655: .Dq no .
1.6 aaron 656: .It Cm X11DisplayOffset
657: Specifies the first display number available for
658: .Nm sshd Ns 's
1.36 aaron 659: X11 forwarding.
660: This prevents
1.6 aaron 661: .Nm
662: from interfering with real X11 servers.
1.34 markus 663: The default is 10.
1.30 markus 664: .It Cm X11Forwarding
1.36 aaron 665: Specifies whether X11 forwarding is permitted.
666: The default is
1.34 markus 667: .Dq no .
1.30 markus 668: Note that disabling X11 forwarding does not improve security in any
669: way, as users can always install their own forwarders.
1.52 markus 670: .It Cm XAuthLocation
671: Specifies the location of the
672: .Xr xauth 1
673: program.
674: The default is
675: .Pa /usr/X11R6/bin/xauth .
1.2 deraadt 676: .El
677: .Sh LOGIN PROCESS
1.1 deraadt 678: When a user successfully logs in,
1.2 deraadt 679: .Nm
1.1 deraadt 680: does the following:
1.2 deraadt 681: .Bl -enum -offset indent
682: .It
1.1 deraadt 683: If the login is on a tty, and no command has been specified,
1.40 aaron 684: prints last login time and
1.2 deraadt 685: .Pa /etc/motd
1.1 deraadt 686: (unless prevented in the configuration file or by
1.2 deraadt 687: .Pa $HOME/.hushlogin ;
688: see the
1.40 aaron 689: .Sx FILES
1.2 deraadt 690: section).
691: .It
1.1 deraadt 692: If the login is on a tty, records login time.
1.2 deraadt 693: .It
694: Checks
695: .Pa /etc/nologin ;
696: if it exists, prints contents and quits
1.1 deraadt 697: (unless root).
1.2 deraadt 698: .It
1.1 deraadt 699: Changes to run with normal user privileges.
1.2 deraadt 700: .It
1.1 deraadt 701: Sets up basic environment.
1.2 deraadt 702: .It
703: Reads
704: .Pa $HOME/.ssh/environment
705: if it exists.
706: .It
1.1 deraadt 707: Changes to user's home directory.
1.2 deraadt 708: .It
709: If
710: .Pa $HOME/.ssh/rc
711: exists, runs it; else if
712: .Pa /etc/sshrc
713: exists, runs
1.36 aaron 714: it; otherwise runs xauth.
715: The
1.2 deraadt 716: .Dq rc
717: files are given the X11
1.1 deraadt 718: authentication protocol and cookie in standard input.
1.2 deraadt 719: .It
1.1 deraadt 720: Runs user's shell or command.
1.2 deraadt 721: .El
722: .Sh AUTHORIZED_KEYS FILE FORMAT
1.40 aaron 723: The
1.2 deraadt 724: .Pa $HOME/.ssh/authorized_keys
1.1 deraadt 725: file lists the RSA keys that are
1.44 deraadt 726: permitted for RSA authentication in SSH protocols 1.3 and 1.5
1.51 hugh 727: Similarly, the
1.44 deraadt 728: .Pa $HOME/.ssh/authorized_keys2
729: file lists the DSA keys that are
730: permitted for DSA authentication in SSH protocol 2.0.
1.36 aaron 731: Each line of the file contains one
1.2 deraadt 732: key (empty lines and lines starting with a
733: .Ql #
734: are ignored as
1.36 aaron 735: comments).
736: Each line consists of the following fields, separated by
737: spaces: options, bits, exponent, modulus, comment.
738: The options field
1.1 deraadt 739: is optional; its presence is determined by whether the line starts
740: with a number or not (the option field never starts with a number).
741: The bits, exponent, modulus and comment fields give the RSA key; the
742: comment field is not used for anything (but may be convenient for the
743: user to identify the key).
1.2 deraadt 744: .Pp
1.1 deraadt 745: Note that lines in this file are usually several hundred bytes long
1.36 aaron 746: (because of the size of the RSA key modulus).
747: You don't want to type them in; instead, copy the
1.2 deraadt 748: .Pa identity.pub
1.1 deraadt 749: file and edit it.
1.2 deraadt 750: .Pp
1.58 deraadt 751: The options (if present) consist of comma-separated option
1.36 aaron 752: specifications.
753: No spaces are permitted, except within double quotes.
1.1 deraadt 754: The following option specifications are supported:
1.2 deraadt 755: .Bl -tag -width Ds
756: .It Cm from="pattern-list"
1.1 deraadt 757: Specifies that in addition to RSA authentication, the canonical name
758: of the remote host must be present in the comma-separated list of
1.36 aaron 759: patterns
760: .Pf ( Ql *
761: and
762: .Ql ?
763: serve as wildcards).
764: The list may also contain
765: patterns negated by prefixing them with
766: .Ql ! ;
767: if the canonical host name matches a negated pattern, the key is not accepted.
768: The purpose
1.1 deraadt 769: of this option is to optionally increase security: RSA authentication
770: by itself does not trust the network or name servers or anything (but
771: the key); however, if somebody somehow steals the key, the key
1.36 aaron 772: permits an intruder to log in from anywhere in the world.
773: This additional option makes using a stolen key more difficult (name
1.1 deraadt 774: servers and/or routers would have to be compromised in addition to
775: just the key).
1.2 deraadt 776: .It Cm command="command"
1.1 deraadt 777: Specifies that the command is executed whenever this key is used for
1.36 aaron 778: authentication.
779: The command supplied by the user (if any) is ignored.
1.1 deraadt 780: The command is run on a pty if the connection requests a pty;
1.36 aaron 781: otherwise it is run without a tty.
782: A quote may be included in the command by quoting it with a backslash.
783: This option might be useful
784: to restrict certain RSA keys to perform just a specific operation.
785: An example might be a key that permits remote backups but nothing else.
1.51 hugh 786: Note that the client may specify TCP/IP and/or X11
787: forwarding unless they are explicitly prohibited.
1.2 deraadt 788: .It Cm environment="NAME=value"
1.1 deraadt 789: Specifies that the string is to be added to the environment when
1.36 aaron 790: logging in using this key.
791: Environment variables set this way
792: override other default environment values.
793: Multiple options of this type are permitted.
1.2 deraadt 794: .It Cm no-port-forwarding
1.1 deraadt 795: Forbids TCP/IP forwarding when this key is used for authentication.
1.36 aaron 796: Any port forward requests by the client will return an error.
797: This might be used, e.g., in connection with the
1.2 deraadt 798: .Cm command
1.1 deraadt 799: option.
1.2 deraadt 800: .It Cm no-X11-forwarding
1.1 deraadt 801: Forbids X11 forwarding when this key is used for authentication.
802: Any X11 forward requests by the client will return an error.
1.2 deraadt 803: .It Cm no-agent-forwarding
1.1 deraadt 804: Forbids authentication agent forwarding when this key is used for
805: authentication.
1.2 deraadt 806: .It Cm no-pty
1.1 deraadt 807: Prevents tty allocation (a request to allocate a pty will fail).
1.2 deraadt 808: .El
809: .Ss Examples
1.1 deraadt 810: 1024 33 12121.\|.\|.\|312314325 ylo@foo.bar
1.2 deraadt 811: .Pp
1.1 deraadt 812: from="*.niksula.hut.fi,!pc.niksula.hut.fi" 1024 35 23.\|.\|.\|2334 ylo@niksula
1.2 deraadt 813: .Pp
1.1 deraadt 814: command="dump /home",no-pty,no-port-forwarding 1024 33 23.\|.\|.\|2323 backup.hut.fi
1.2 deraadt 815: .Sh SSH_KNOWN_HOSTS FILE FORMAT
1.40 aaron 816: The
1.44 deraadt 817: .Pa /etc/ssh_known_hosts ,
818: .Pa /etc/ssh_known_hosts2 ,
819: .Pa $HOME/.ssh/known_hosts ,
1.40 aaron 820: and
1.44 deraadt 821: .Pa $HOME/.ssh/known_hosts2
1.36 aaron 822: files contain host public keys for all known hosts.
823: The global file should
1.37 brad 824: be prepared by the administrator (optional), and the per-user file is
1.58 deraadt 825: maintained automatically: whenever the user connects from an unknown host
1.36 aaron 826: its key is added to the per-user file.
1.2 deraadt 827: .Pp
1.1 deraadt 828: Each line in these files contains the following fields: hostnames,
1.36 aaron 829: bits, exponent, modulus, comment.
830: The fields are separated by spaces.
1.2 deraadt 831: .Pp
1.1 deraadt 832: Hostnames is a comma-separated list of patterns ('*' and '?' act as
833: wildcards); each pattern in turn is matched against the canonical host
834: name (when authenticating a client) or against the user-supplied
1.36 aaron 835: name (when authenticating a server).
836: A pattern may also be preceded by
1.2 deraadt 837: .Ql !
838: to indicate negation: if the host name matches a negated
1.1 deraadt 839: pattern, it is not accepted (by that line) even if it matched another
840: pattern on the line.
1.2 deraadt 841: .Pp
1.49 markus 842: Bits, exponent, and modulus are taken directly from the RSA host key; they
1.2 deraadt 843: can be obtained, e.g., from
844: .Pa /etc/ssh_host_key.pub .
1.1 deraadt 845: The optional comment field continues to the end of the line, and is not used.
1.2 deraadt 846: .Pp
847: Lines starting with
848: .Ql #
849: and empty lines are ignored as comments.
850: .Pp
1.1 deraadt 851: When performing host authentication, authentication is accepted if any
1.36 aaron 852: matching line has the proper key.
853: It is thus permissible (but not
1.1 deraadt 854: recommended) to have several lines or different host keys for the same
1.36 aaron 855: names.
856: This will inevitably happen when short forms of host names
857: from different domains are put in the file.
858: It is possible
1.1 deraadt 859: that the files contain conflicting information; authentication is
860: accepted if valid information can be found from either file.
1.2 deraadt 861: .Pp
1.1 deraadt 862: Note that the lines in these files are typically hundreds of characters
863: long, and you definitely don't want to type in the host keys by hand.
1.6 aaron 864: Rather, generate them by a script
1.40 aaron 865: or by taking
1.2 deraadt 866: .Pa /etc/ssh_host_key.pub
1.1 deraadt 867: and adding the host names at the front.
1.2 deraadt 868: .Ss Examples
1.1 deraadt 869: closenet,closenet.hut.fi,.\|.\|.\|,130.233.208.41 1024 37 159.\|.\|.93 closenet.hut.fi
1.2 deraadt 870: .Sh FILES
871: .Bl -tag -width Ds
872: .It Pa /etc/sshd_config
1.1 deraadt 873: Contains configuration data for
1.2 deraadt 874: .Nm sshd .
1.1 deraadt 875: This file should be writable by root only, but it is recommended
876: (though not necessary) that it be world-readable.
1.2 deraadt 877: .It Pa /etc/ssh_host_key
1.7 markus 878: Contains the private part of the host key.
1.1 deraadt 879: This file should only be owned by root, readable only by root, and not
880: accessible to others.
1.14 markus 881: Note that
882: .Nm
883: does not start if this file is group/world-accessible.
1.2 deraadt 884: .It Pa /etc/ssh_host_key.pub
1.7 markus 885: Contains the public part of the host key.
886: This file should be world-readable but writable only by
1.36 aaron 887: root.
888: Its contents should match the private part.
889: This file is not
1.1 deraadt 890: really used for anything; it is only provided for the convenience of
891: the user so its contents can be copied to known hosts files.
1.7 markus 892: These two files are created using
893: .Xr ssh-keygen 1 .
1.73 provos 894: .It Pa /etc/primes
895: Contains Diffie-Hellman groups used for the "Diffie-Hellman Group Exchange".
1.2 deraadt 896: .It Pa /var/run/sshd.pid
897: Contains the process ID of the
898: .Nm
1.1 deraadt 899: listening for connections (if there are several daemons running
900: concurrently for different ports, this contains the pid of the one
1.36 aaron 901: started last).
1.58 deraadt 902: The content of this file is not sensitive; it can be world-readable.
1.2 deraadt 903: .It Pa $HOME/.ssh/authorized_keys
1.1 deraadt 904: Lists the RSA keys that can be used to log into the user's account.
905: This file must be readable by root (which may on some machines imply
906: it being world-readable if the user's home directory resides on an NFS
1.36 aaron 907: volume).
908: It is recommended that it not be accessible by others.
909: The format of this file is described above.
1.44 deraadt 910: Users will place the contents of their
911: .Pa identity.pub
912: files into this file, as described in
913: .Xr ssh-keygen 1 .
914: .It Pa $HOME/.ssh/authorized_keys2
915: Lists the DSA keys that can be used to log into the user's account.
916: This file must be readable by root (which may on some machines imply
917: it being world-readable if the user's home directory resides on an NFS
918: volume).
919: It is recommended that it not be accessible by others.
920: The format of this file is described above.
921: Users will place the contents of their
922: .Pa id_dsa.pub
923: files into this file, as described in
924: .Xr ssh-keygen 1 .
1.22 markus 925: .It Pa "/etc/ssh_known_hosts" and "$HOME/.ssh/known_hosts"
926: These files are consulted when using rhosts with RSA host
1.36 aaron 927: authentication to check the public key of the host.
928: The key must be listed in one of these files to be accepted.
1.22 markus 929: The client uses the same files
1.58 deraadt 930: to verify that the remote host is the one it intended to connect.
1.36 aaron 931: These files should be writable only by root/the owner.
1.2 deraadt 932: .Pa /etc/ssh_known_hosts
933: should be world-readable, and
934: .Pa $HOME/.ssh/known_hosts
935: can but need not be world-readable.
1.6 aaron 936: .It Pa /etc/nologin
1.40 aaron 937: If this file exists,
1.2 deraadt 938: .Nm
1.36 aaron 939: refuses to let anyone except root log in.
940: The contents of the file
1.1 deraadt 941: are displayed to anyone trying to log in, and non-root connections are
1.36 aaron 942: refused.
943: The file should be world-readable.
1.19 dugsong 944: .It Pa /etc/hosts.allow, /etc/hosts.deny
945: If compiled with
946: .Sy LIBWRAP
947: support, tcp-wrappers access controls may be defined here as described in
948: .Xr hosts_access 5 .
1.6 aaron 949: .It Pa $HOME/.rhosts
1.1 deraadt 950: This file contains host-username pairs, separated by a space, one per
1.36 aaron 951: line.
952: The given user on the corresponding host is permitted to log in
953: without password.
954: The same file is used by rlogind and rshd.
1.6 aaron 955: The file must
1.1 deraadt 956: be writable only by the user; it is recommended that it not be
957: accessible by others.
1.2 deraadt 958: .Pp
1.36 aaron 959: If is also possible to use netgroups in the file.
960: Either host or user
1.1 deraadt 961: name may be of the form +@groupname to specify all hosts or all users
962: in the group.
1.2 deraadt 963: .It Pa $HOME/.shosts
964: For ssh,
965: this file is exactly the same as for
966: .Pa .rhosts .
967: However, this file is
968: not used by rlogin and rshd, so using this permits access using SSH only.
1.58 deraadt 969: .It Pa /etc/hosts.equiv
1.2 deraadt 970: This file is used during
971: .Pa .rhosts
1.36 aaron 972: authentication.
973: In the simplest form, this file contains host names, one per line.
974: Users on
1.1 deraadt 975: those hosts are permitted to log in without a password, provided they
1.36 aaron 976: have the same user name on both machines.
977: The host name may also be
1.1 deraadt 978: followed by a user name; such users are permitted to log in as
1.2 deraadt 979: .Em any
1.36 aaron 980: user on this machine (except root).
981: Additionally, the syntax
1.2 deraadt 982: .Dq +@group
1.36 aaron 983: can be used to specify netgroups.
984: Negated entries start with
1.2 deraadt 985: .Ql \&- .
986: .Pp
1.1 deraadt 987: If the client host/user is successfully matched in this file, login is
988: automatically permitted provided the client and server user names are the
1.36 aaron 989: same.
990: Additionally, successful RSA host authentication is normally required.
991: This file must be writable only by root; it is recommended
1.1 deraadt 992: that it be world-readable.
1.2 deraadt 993: .Pp
1.6 aaron 994: .Sy "Warning: It is almost never a good idea to use user names in"
1.2 deraadt 995: .Pa hosts.equiv .
1.1 deraadt 996: Beware that it really means that the named user(s) can log in as
1.2 deraadt 997: .Em anybody ,
1.1 deraadt 998: which includes bin, daemon, adm, and other accounts that own critical
1.36 aaron 999: binaries and directories.
1000: Using a user name practically grants the user root access.
1001: The only valid use for user names that I can think
1.1 deraadt 1002: of is in negative entries.
1.2 deraadt 1003: .Pp
1004: Note that this warning also applies to rsh/rlogin.
1005: .It Pa /etc/shosts.equiv
1.1 deraadt 1006: This is processed exactly as
1.2 deraadt 1007: .Pa /etc/hosts.equiv .
1.1 deraadt 1008: However, this file may be useful in environments that want to run both
1.2 deraadt 1009: rsh/rlogin and ssh.
1.6 aaron 1010: .It Pa $HOME/.ssh/environment
1.36 aaron 1011: This file is read into the environment at login (if it exists).
1012: It can only contain empty lines, comment lines (that start with
1.2 deraadt 1013: .Ql # ) ,
1.36 aaron 1014: and assignment lines of the form name=value.
1015: The file should be writable
1.6 aaron 1016: only by the user; it need not be readable by anyone else.
1.2 deraadt 1017: .It Pa $HOME/.ssh/rc
1.1 deraadt 1018: If this file exists, it is run with /bin/sh after reading the
1.36 aaron 1019: environment files but before starting the user's shell or command.
1020: If X11 spoofing is in use, this will receive the "proto cookie" pair in
1.2 deraadt 1021: standard input (and
1022: .Ev DISPLAY
1.36 aaron 1023: in environment).
1024: This must call
1.2 deraadt 1025: .Xr xauth 1
1026: in that case.
1027: .Pp
1.1 deraadt 1028: The primary purpose of this file is to run any initialization routines
1029: which may be needed before the user's home directory becomes
1030: accessible; AFS is a particular example of such an environment.
1.2 deraadt 1031: .Pp
1.1 deraadt 1032: This file will probably contain some initialization code followed by
1033: something similar to: "if read proto cookie; then echo add $DISPLAY
1034: $proto $cookie | xauth -q -; fi".
1.2 deraadt 1035: .Pp
1036: If this file does not exist,
1037: .Pa /etc/sshrc
1038: is run, and if that
1.1 deraadt 1039: does not exist either, xauth is used to store the cookie.
1.2 deraadt 1040: .Pp
1.1 deraadt 1041: This file should be writable only by the user, and need not be
1042: readable by anyone else.
1.2 deraadt 1043: .It Pa /etc/sshrc
1044: Like
1045: .Pa $HOME/.ssh/rc .
1046: This can be used to specify
1.36 aaron 1047: machine-specific login-time initializations globally.
1048: This file should be writable only by root, and should be world-readable.
1.56 aaron 1049: .El
1.71 aaron 1050: .Sh AUTHORS
1.17 deraadt 1051: OpenSSH
1.33 deraadt 1052: is a derivative of the original (free) ssh 1.2.12 release by Tatu Ylonen,
1.36 aaron 1053: but with bugs removed and newer features re-added.
1054: Rapidly after the
1.33 deraadt 1055: 1.2.12 release, newer versions of the original ssh bore successively
1056: more restrictive licenses, and thus demand for a free version was born.
1.48 markus 1057: .Pp
1.33 deraadt 1058: This version of OpenSSH
1.17 deraadt 1059: .Bl -bullet
1060: .It
1.32 aaron 1061: has all components of a restrictive nature (i.e., patents, see
1.17 deraadt 1062: .Xr ssl 8 )
1063: directly removed from the source code; any licensed or patented components
1064: are chosen from
1065: external libraries.
1066: .It
1.48 markus 1067: has been updated to support SSH protocol 1.5 and 2, making it compatible with
1068: all other SSH clients and servers.
1.17 deraadt 1069: .It
1.40 aaron 1070: contains added support for
1.17 deraadt 1071: .Xr kerberos 8
1072: authentication and ticket passing.
1073: .It
1074: supports one-time password authentication with
1075: .Xr skey 1 .
1076: .El
1.48 markus 1077: .Pp
1078: OpenSSH has been created by Aaron Campbell, Bob Beck, Markus Friedl,
1079: Niels Provos, Theo de Raadt, and Dug Song.
1080: .Pp
1081: The support for SSH protocol 2 was written by Markus Friedl.
1.2 deraadt 1082: .Sh SEE ALSO
1083: .Xr scp 1 ,
1.63 markus 1084: .Xr sftp-server 8 ,
1.2 deraadt 1085: .Xr ssh 1 ,
1.5 deraadt 1086: .Xr ssh-add 1 ,
1.2 deraadt 1087: .Xr ssh-agent 1 ,
1.5 deraadt 1088: .Xr ssh-keygen 1 ,
1.38 deraadt 1089: .Xr ssl 8 ,
1090: .Xr rlogin 1 ,
1091: .Xr rsh 1
![[BACK]](/icons/back.gif){kind=icon}
Return to sshd.8 CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh