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-rw-r--r--sshd_config.0360
1 files changed, 200 insertions, 160 deletions
diff --git a/sshd_config.0 b/sshd_config.0
index 1c82d449f..be48e1364 100644
--- a/sshd_config.0
+++ b/sshd_config.0
@@ -1,7 +1,7 @@
1SSHD_CONFIG(5) File Formats Manual SSHD_CONFIG(5) 1SSHD_CONFIG(5) File Formats Manual SSHD_CONFIG(5)
2 2
3NAME 3NAME
4 sshd_config - OpenSSH SSH daemon configuration file 4 sshd_config M-bM-^@M-^S OpenSSH SSH daemon configuration file
5 5
6SYNOPSIS 6SYNOPSIS
7 /etc/ssh/sshd_config 7 /etc/ssh/sshd_config
@@ -9,7 +9,7 @@ SYNOPSIS
9DESCRIPTION 9DESCRIPTION
10 sshd(8) reads configuration data from /etc/ssh/sshd_config (or the file 10 sshd(8) reads configuration data from /etc/ssh/sshd_config (or the file
11 specified with -f on the command line). The file contains keyword- 11 specified with -f on the command line). The file contains keyword-
12 argument pairs, one per line. Lines starting with `#' and empty lines 12 argument pairs, one per line. Lines starting with M-bM-^@M-^X#M-bM-^@M-^Y and empty lines
13 are interpreted as comments. Arguments may optionally be enclosed in 13 are interpreted as comments. Arguments may optionally be enclosed in
14 double quotes (") in order to represent arguments containing spaces. 14 double quotes (") in order to represent arguments containing spaces.
15 15
@@ -22,7 +22,7 @@ DESCRIPTION
22 ssh_config(5) for how to configure the client. Note that 22 ssh_config(5) for how to configure the client. Note that
23 environment passing is only supported for protocol 2. Variables 23 environment passing is only supported for protocol 2. Variables
24 are specified by name, which may contain the wildcard characters 24 are specified by name, which may contain the wildcard characters
25 `*' and `?'. Multiple environment variables may be separated by 25 M-bM-^@M-^X*M-bM-^@M-^Y and M-bM-^@M-^X?M-bM-^@M-^Y. Multiple environment variables may be separated by
26 whitespace or spread across multiple AcceptEnv directives. Be 26 whitespace or spread across multiple AcceptEnv directives. Be
27 warned that some environment variables could be used to bypass 27 warned that some environment variables could be used to bypass
28 restricted user environments. For this reason, care should be 28 restricted user environments. For this reason, care should be
@@ -31,14 +31,14 @@ DESCRIPTION
31 31
32 AddressFamily 32 AddressFamily
33 Specifies which address family should be used by sshd(8). Valid 33 Specifies which address family should be used by sshd(8). Valid
34 arguments are ``any'', ``inet'' (use IPv4 only), or ``inet6'' 34 arguments are M-bM-^@M-^\anyM-bM-^@M-^], M-bM-^@M-^\inetM-bM-^@M-^] (use IPv4 only), or M-bM-^@M-^\inet6M-bM-^@M-^] (use IPv6
35 (use IPv6 only). The default is ``any''. 35 only). The default is M-bM-^@M-^\anyM-bM-^@M-^].
36 36
37 AllowAgentForwarding 37 AllowAgentForwarding
38 Specifies whether ssh-agent(1) forwarding is permitted. The 38 Specifies whether ssh-agent(1) forwarding is permitted. The
39 default is ``yes''. Note that disabling agent forwarding does 39 default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that disabling agent forwarding does not
40 not improve security unless users are also denied shell access, 40 improve security unless users are also denied shell access, as
41 as they can always install their own forwarders. 41 they can always install their own forwarders.
42 42
43 AllowGroups 43 AllowGroups
44 This keyword can be followed by a list of group name patterns, 44 This keyword can be followed by a list of group name patterns,
@@ -54,21 +54,21 @@ DESCRIPTION
54 54
55 AllowTcpForwarding 55 AllowTcpForwarding
56 Specifies whether TCP forwarding is permitted. The available 56 Specifies whether TCP forwarding is permitted. The available
57 options are ``yes'' or ``all'' to allow TCP forwarding, ``no'' to 57 options are M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\allM-bM-^@M-^] to allow TCP forwarding, M-bM-^@M-^\noM-bM-^@M-^] to
58 prevent all TCP forwarding, ``local'' to allow local (from the 58 prevent all TCP forwarding, M-bM-^@M-^\localM-bM-^@M-^] to allow local (from the
59 perspective of ssh(1)) forwarding only or ``remote'' to allow 59 perspective of ssh(1)) forwarding only or M-bM-^@M-^\remoteM-bM-^@M-^] to allow
60 remote forwarding only. The default is ``yes''. Note that 60 remote forwarding only. The default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that
61 disabling TCP forwarding does not improve security unless users 61 disabling TCP forwarding does not improve security unless users
62 are also denied shell access, as they can always install their 62 are also denied shell access, as they can always install their
63 own forwarders. 63 own forwarders.
64 64
65 AllowStreamLocalForwarding 65 AllowStreamLocalForwarding
66 Specifies whether StreamLocal (Unix-domain socket) forwarding is 66 Specifies whether StreamLocal (Unix-domain socket) forwarding is
67 permitted. The available options are ``yes'' or ``all'' to allow 67 permitted. The available options are M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\allM-bM-^@M-^] to allow
68 StreamLocal forwarding, ``no'' to prevent all StreamLocal 68 StreamLocal forwarding, M-bM-^@M-^\noM-bM-^@M-^] to prevent all StreamLocal
69 forwarding, ``local'' to allow local (from the perspective of 69 forwarding, M-bM-^@M-^\localM-bM-^@M-^] to allow local (from the perspective of
70 ssh(1)) forwarding only or ``remote'' to allow remote forwarding 70 ssh(1)) forwarding only or M-bM-^@M-^\remoteM-bM-^@M-^] to allow remote forwarding
71 only. The default is ``yes''. Note that disabling StreamLocal 71 only. The default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that disabling StreamLocal
72 forwarding does not improve security unless users are also denied 72 forwarding does not improve security unless users are also denied
73 shell access, as they can always install their own forwarders. 73 shell access, as they can always install their own forwarders.
74 74
@@ -92,8 +92,8 @@ DESCRIPTION
92 method names. Successful authentication requires completion of 92 method names. Successful authentication requires completion of
93 every method in at least one of these lists. 93 every method in at least one of these lists.
94 94
95 For example, an argument of ``publickey,password 95 For example, an argument of M-bM-^@M-^\publickey,password
96 publickey,keyboard-interactive'' would require the user to 96 publickey,keyboard-interactiveM-bM-^@M-^] would require the user to
97 complete public key authentication, followed by either password 97 complete public key authentication, followed by either password
98 or keyboard interactive authentication. Only methods that are 98 or keyboard interactive authentication. Only methods that are
99 next in one or more lists are offered at each stage, so for this 99 next in one or more lists are offered at each stage, so for this
@@ -102,10 +102,16 @@ DESCRIPTION
102 102
103 For keyboard interactive authentication it is also possible to 103 For keyboard interactive authentication it is also possible to
104 restrict authentication to a specific device by appending a colon 104 restrict authentication to a specific device by appending a colon
105 followed by the device identifier ``bsdauth'', ``pam'', or 105 followed by the device identifier M-bM-^@M-^\bsdauthM-bM-^@M-^], M-bM-^@M-^\pamM-bM-^@M-^], or M-bM-^@M-^\skeyM-bM-^@M-^],
106 ``skey'', depending on the server configuration. For example, 106 depending on the server configuration. For example,
107 ``keyboard-interactive:bsdauth'' would restrict keyboard 107 M-bM-^@M-^\keyboard-interactive:bsdauthM-bM-^@M-^] would restrict keyboard
108 interactive authentication to the ``bsdauth'' device. 108 interactive authentication to the M-bM-^@M-^\bsdauthM-bM-^@M-^] device.
109
110 If the M-bM-^@M-^\publickeyM-bM-^@M-^] method is listed more than once, sshd(8)
111 verifies that keys that have been used successfully are not
112 reused for subsequent authentications. For example, an
113 AuthenticationMethods of M-bM-^@M-^\publickey,publickeyM-bM-^@M-^] will require
114 successful authentication using two different public keys.
109 115
110 This option is only available for SSH protocol 2 and will yield a 116 This option is only available for SSH protocol 2 and will yield a
111 fatal error if enabled if protocol 1 is also enabled. Note that 117 fatal error if enabled if protocol 1 is also enabled. Note that
@@ -129,7 +135,9 @@ DESCRIPTION
129 AuthorizedKeysCommandUser 135 AuthorizedKeysCommandUser
130 Specifies the user under whose account the AuthorizedKeysCommand 136 Specifies the user under whose account the AuthorizedKeysCommand
131 is run. It is recommended to use a dedicated user that has no 137 is run. It is recommended to use a dedicated user that has no
132 other role on the host than running authorized keys commands. 138 other role on the host than running authorized keys commands. If
139 AuthorizedKeysCommand is specified but AuthorizedKeysCommandUser
140 is not, then sshd(8) will refuse to start.
133 141
134 AuthorizedKeysFile 142 AuthorizedKeysFile
135 Specifies the file that contains the public keys that can be used 143 Specifies the file that contains the public keys that can be used
@@ -143,7 +151,7 @@ DESCRIPTION
143 AuthorizedKeysFile is taken to be an absolute path or one 151 AuthorizedKeysFile is taken to be an absolute path or one
144 relative to the user's home directory. Multiple files may be 152 relative to the user's home directory. Multiple files may be
145 listed, separated by whitespace. The default is 153 listed, separated by whitespace. The default is
146 ``.ssh/authorized_keys .ssh/authorized_keys2''. 154 M-bM-^@M-^\.ssh/authorized_keys .ssh/authorized_keys2M-bM-^@M-^].
147 155
148 AuthorizedPrincipalsFile 156 AuthorizedPrincipalsFile
149 Specifies a file that lists principal names that are accepted for 157 Specifies a file that lists principal names that are accepted for
@@ -152,7 +160,7 @@ DESCRIPTION
152 which must appear in the certificate for it to be accepted for 160 which must appear in the certificate for it to be accepted for
153 authentication. Names are listed one per line preceded by key 161 authentication. Names are listed one per line preceded by key
154 options (as described in AUTHORIZED_KEYS FILE FORMAT in sshd(8)). 162 options (as described in AUTHORIZED_KEYS FILE FORMAT in sshd(8)).
155 Empty lines and comments starting with `#' are ignored. 163 Empty lines and comments starting with M-bM-^@M-^X#M-bM-^@M-^Y are ignored.
156 164
157 AuthorizedPrincipalsFile may contain tokens of the form %T which 165 AuthorizedPrincipalsFile may contain tokens of the form %T which
158 are substituted during connection setup. The following tokens 166 are substituted during connection setup. The following tokens
@@ -162,7 +170,7 @@ DESCRIPTION
162 AuthorizedPrincipalsFile is taken to be an absolute path or one 170 AuthorizedPrincipalsFile is taken to be an absolute path or one
163 relative to the user's home directory. 171 relative to the user's home directory.
164 172
165 The default is ``none'', i.e. not to use a principals file - in 173 The default is M-bM-^@M-^\noneM-bM-^@M-^], i.e. not to use a principals file M-bM-^@M-^S in
166 this case, the username of the user must appear in a 174 this case, the username of the user must appear in a
167 certificate's principals list for it to be accepted. Note that 175 certificate's principals list for it to be accepted. Note that
168 AuthorizedPrincipalsFile is only used when authentication 176 AuthorizedPrincipalsFile is only used when authentication
@@ -172,21 +180,22 @@ DESCRIPTION
172 a similar facility (see sshd(8) for details). 180 a similar facility (see sshd(8) for details).
173 181
174 Banner The contents of the specified file are sent to the remote user 182 Banner The contents of the specified file are sent to the remote user
175 before authentication is allowed. If the argument is ``none'' 183 before authentication is allowed. If the argument is M-bM-^@M-^\noneM-bM-^@M-^] then
176 then no banner is displayed. This option is only available for 184 no banner is displayed. This option is only available for
177 protocol version 2. By default, no banner is displayed. 185 protocol version 2. By default, no banner is displayed.
178 186
179 ChallengeResponseAuthentication 187 ChallengeResponseAuthentication
180 Specifies whether challenge-response authentication is allowed 188 Specifies whether challenge-response authentication is allowed
181 (e.g. via PAM or through authentication styles supported in 189 (e.g. via PAM or through authentication styles supported in
182 login.conf(5)) The default is ``yes''. 190 login.conf(5)) The default is M-bM-^@M-^\yesM-bM-^@M-^].
183 191
184 ChrootDirectory 192 ChrootDirectory
185 Specifies the pathname of a directory to chroot(2) to after 193 Specifies the pathname of a directory to chroot(2) to after
186 authentication. All components of the pathname must be root- 194 authentication. At session startup sshd(8) checks that all
187 owned directories that are not writable by any other user or 195 components of the pathname are root-owned directories which are
188 group. After the chroot, sshd(8) changes the working directory 196 not writable by any other user or group. After the chroot,
189 to the user's home directory. 197 sshd(8) changes the working directory to the user's home
198 directory.
190 199
191 The pathname may contain the following tokens that are expanded 200 The pathname may contain the following tokens that are expanded
192 at runtime once the connecting user has been authenticated: %% is 201 at runtime once the connecting user has been authenticated: %% is
@@ -198,12 +207,17 @@ DESCRIPTION
198 directories to support the user's session. For an interactive 207 directories to support the user's session. For an interactive
199 session this requires at least a shell, typically sh(1), and 208 session this requires at least a shell, typically sh(1), and
200 basic /dev nodes such as null(4), zero(4), stdin(4), stdout(4), 209 basic /dev nodes such as null(4), zero(4), stdin(4), stdout(4),
201 stderr(4), arandom(4) and tty(4) devices. For file transfer 210 stderr(4), and tty(4) devices. For file transfer sessions using
202 sessions using ``sftp'', no additional configuration of the 211 M-bM-^@M-^\sftpM-bM-^@M-^], no additional configuration of the environment is
203 environment is necessary if the in-process sftp server is used, 212 necessary if the in-process sftp server is used, though sessions
204 though sessions which use logging may require /dev/log inside the 213 which use logging may require /dev/log inside the chroot
205 chroot directory on some operating systems (see sftp-server(8) 214 directory on some operating systems (see sftp-server(8) for
206 for details). 215 details).
216
217 For safety, it is very important that the directory hierarchy be
218 prevented from modification by other processes on the system
219 (especially those outside the jail). Misconfiguration can lead
220 to unsafe environments which sshd(8) cannot detect.
207 221
208 The default is not to chroot(2). 222 The default is not to chroot(2).
209 223
@@ -234,7 +248,7 @@ DESCRIPTION
234 chacha20-poly1305@openssh.com 248 chacha20-poly1305@openssh.com
235 249
236 The list of available ciphers may also be obtained using the -Q 250 The list of available ciphers may also be obtained using the -Q
237 option of ssh(1). 251 option of ssh(1) with an argument of M-bM-^@M-^\cipherM-bM-^@M-^].
238 252
239 ClientAliveCountMax 253 ClientAliveCountMax
240 Sets the number of client alive messages (see below) which may be 254 Sets the number of client alive messages (see below) which may be
@@ -264,8 +278,8 @@ DESCRIPTION
264 278
265 Compression 279 Compression
266 Specifies whether compression is allowed, or delayed until the 280 Specifies whether compression is allowed, or delayed until the
267 user has authenticated successfully. The argument must be 281 user has authenticated successfully. The argument must be M-bM-^@M-^\yesM-bM-^@M-^],
268 ``yes'', ``delayed'', or ``no''. The default is ``delayed''. 282 M-bM-^@M-^\delayedM-bM-^@M-^], or M-bM-^@M-^\noM-bM-^@M-^]. The default is M-bM-^@M-^\delayedM-bM-^@M-^].
269 283
270 DenyGroups 284 DenyGroups
271 This keyword can be followed by a list of group name patterns, 285 This keyword can be followed by a list of group name patterns,
@@ -291,6 +305,10 @@ DESCRIPTION
291 305
292 See PATTERNS in ssh_config(5) for more information on patterns. 306 See PATTERNS in ssh_config(5) for more information on patterns.
293 307
308 FingerprintHash
309 Specifies the hash algorithm used when logging key fingerprints.
310 Valid options are: M-bM-^@M-^\md5M-bM-^@M-^] and M-bM-^@M-^\sha256M-bM-^@M-^]. The default is M-bM-^@M-^\sha256M-bM-^@M-^].
311
294 ForceCommand 312 ForceCommand
295 Forces the execution of the command specified by ForceCommand, 313 Forces the execution of the command specified by ForceCommand,
296 ignoring any command supplied by the client and ~/.ssh/rc if 314 ignoring any command supplied by the client and ~/.ssh/rc if
@@ -299,7 +317,7 @@ DESCRIPTION
299 execution. It is most useful inside a Match block. The command 317 execution. It is most useful inside a Match block. The command
300 originally supplied by the client is available in the 318 originally supplied by the client is available in the
301 SSH_ORIGINAL_COMMAND environment variable. Specifying a command 319 SSH_ORIGINAL_COMMAND environment variable. Specifying a command
302 of ``internal-sftp'' will force the use of an in-process sftp 320 of M-bM-^@M-^\internal-sftpM-bM-^@M-^] will force the use of an in-process sftp
303 server that requires no support files when used with 321 server that requires no support files when used with
304 ChrootDirectory. 322 ChrootDirectory.
305 323
@@ -310,37 +328,43 @@ DESCRIPTION
310 hosts from connecting to forwarded ports. GatewayPorts can be 328 hosts from connecting to forwarded ports. GatewayPorts can be
311 used to specify that sshd should allow remote port forwardings to 329 used to specify that sshd should allow remote port forwardings to
312 bind to non-loopback addresses, thus allowing other hosts to 330 bind to non-loopback addresses, thus allowing other hosts to
313 connect. The argument may be ``no'' to force remote port 331 connect. The argument may be M-bM-^@M-^\noM-bM-^@M-^] to force remote port
314 forwardings to be available to the local host only, ``yes'' to 332 forwardings to be available to the local host only, M-bM-^@M-^\yesM-bM-^@M-^] to
315 force remote port forwardings to bind to the wildcard address, or 333 force remote port forwardings to bind to the wildcard address, or
316 ``clientspecified'' to allow the client to select the address to 334 M-bM-^@M-^\clientspecifiedM-bM-^@M-^] to allow the client to select the address to
317 which the forwarding is bound. The default is ``no''. 335 which the forwarding is bound. The default is M-bM-^@M-^\noM-bM-^@M-^].
318 336
319 GSSAPIAuthentication 337 GSSAPIAuthentication
320 Specifies whether user authentication based on GSSAPI is allowed. 338 Specifies whether user authentication based on GSSAPI is allowed.
321 The default is ``no''. Note that this option applies to protocol 339 The default is M-bM-^@M-^\noM-bM-^@M-^]. Note that this option applies to protocol
322 version 2 only. 340 version 2 only.
323 341
324 GSSAPICleanupCredentials 342 GSSAPICleanupCredentials
325 Specifies whether to automatically destroy the user's credentials 343 Specifies whether to automatically destroy the user's credentials
326 cache on logout. The default is ``yes''. Note that this option 344 cache on logout. The default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that this option
327 applies to protocol version 2 only. 345 applies to protocol version 2 only.
328 346
347 HostbasedAcceptedKeyTypes
348 Specifies the key types that will be accepted for hostbased
349 authentication as a comma-separated pattern list. The default
350 M-bM-^@M-^\*M-bM-^@M-^] will allow all key types. The -Q option of ssh(1) may be
351 used to list supported key types.
352
329 HostbasedAuthentication 353 HostbasedAuthentication
330 Specifies whether rhosts or /etc/hosts.equiv authentication 354 Specifies whether rhosts or /etc/hosts.equiv authentication
331 together with successful public key client host authentication is 355 together with successful public key client host authentication is
332 allowed (host-based authentication). This option is similar to 356 allowed (host-based authentication). This option is similar to
333 RhostsRSAAuthentication and applies to protocol version 2 only. 357 RhostsRSAAuthentication and applies to protocol version 2 only.
334 The default is ``no''. 358 The default is M-bM-^@M-^\noM-bM-^@M-^].
335 359
336 HostbasedUsesNameFromPacketOnly 360 HostbasedUsesNameFromPacketOnly
337 Specifies whether or not the server will attempt to perform a 361 Specifies whether or not the server will attempt to perform a
338 reverse name lookup when matching the name in the ~/.shosts, 362 reverse name lookup when matching the name in the ~/.shosts,
339 ~/.rhosts, and /etc/hosts.equiv files during 363 ~/.rhosts, and /etc/hosts.equiv files during
340 HostbasedAuthentication. A setting of ``yes'' means that sshd(8) 364 HostbasedAuthentication. A setting of M-bM-^@M-^\yesM-bM-^@M-^] means that sshd(8)
341 uses the name supplied by the client rather than attempting to 365 uses the name supplied by the client rather than attempting to
342 resolve the name from the TCP connection itself. The default is 366 resolve the name from the TCP connection itself. The default is
343 ``no''. 367 M-bM-^@M-^\noM-bM-^@M-^].
344 368
345 HostCertificate 369 HostCertificate
346 Specifies a file containing a public host certificate. The 370 Specifies a file containing a public host certificate. The
@@ -355,70 +379,69 @@ DESCRIPTION
355 /etc/ssh/ssh_host_ed25519_key and /etc/ssh/ssh_host_rsa_key for 379 /etc/ssh/ssh_host_ed25519_key and /etc/ssh/ssh_host_rsa_key for
356 protocol version 2. Note that sshd(8) will refuse to use a file 380 protocol version 2. Note that sshd(8) will refuse to use a file
357 if it is group/world-accessible. It is possible to have multiple 381 if it is group/world-accessible. It is possible to have multiple
358 host key files. ``rsa1'' keys are used for version 1 and 382 host key files. M-bM-^@M-^\rsa1M-bM-^@M-^] keys are used for version 1 and M-bM-^@M-^\dsaM-bM-^@M-^],
359 ``dsa'', ``ecdsa'', ``ed25519'' or ``rsa'' are used for version 2 383 M-bM-^@M-^\ecdsaM-bM-^@M-^], M-bM-^@M-^\ed25519M-bM-^@M-^] or M-bM-^@M-^\rsaM-bM-^@M-^] are used for version 2 of the SSH
360 of the SSH protocol. It is also possible to specify public host 384 protocol. It is also possible to specify public host key files
361 key files instead. In this case operations on the private key 385 instead. In this case operations on the private key will be
362 will be delegated to an ssh-agent(1). 386 delegated to an ssh-agent(1).
363 387
364 HostKeyAgent 388 HostKeyAgent
365 Identifies the UNIX-domain socket used to communicate with an 389 Identifies the UNIX-domain socket used to communicate with an
366 agent that has access to the private host keys. If 390 agent that has access to the private host keys. If
367 ``SSH_AUTH_SOCK'' is specified, the location of the socket will 391 M-bM-^@M-^\SSH_AUTH_SOCKM-bM-^@M-^] is specified, the location of the socket will be
368 be read from the SSH_AUTH_SOCK environment variable. 392 read from the SSH_AUTH_SOCK environment variable.
369 393
370 IgnoreRhosts 394 IgnoreRhosts
371 Specifies that .rhosts and .shosts files will not be used in 395 Specifies that .rhosts and .shosts files will not be used in
372 RhostsRSAAuthentication or HostbasedAuthentication. 396 RhostsRSAAuthentication or HostbasedAuthentication.
373 397
374 /etc/hosts.equiv and /etc/shosts.equiv are still used. The 398 /etc/hosts.equiv and /etc/shosts.equiv are still used. The
375 default is ``yes''. 399 default is M-bM-^@M-^\yesM-bM-^@M-^].
376 400
377 IgnoreUserKnownHosts 401 IgnoreUserKnownHosts
378 Specifies whether sshd(8) should ignore the user's 402 Specifies whether sshd(8) should ignore the user's
379 ~/.ssh/known_hosts during RhostsRSAAuthentication or 403 ~/.ssh/known_hosts during RhostsRSAAuthentication or
380 HostbasedAuthentication. The default is ``no''. 404 HostbasedAuthentication. The default is M-bM-^@M-^\noM-bM-^@M-^].
381 405
382 IPQoS Specifies the IPv4 type-of-service or DSCP class for the 406 IPQoS Specifies the IPv4 type-of-service or DSCP class for the
383 connection. Accepted values are ``af11'', ``af12'', ``af13'', 407 connection. Accepted values are M-bM-^@M-^\af11M-bM-^@M-^], M-bM-^@M-^\af12M-bM-^@M-^], M-bM-^@M-^\af13M-bM-^@M-^], M-bM-^@M-^\af21M-bM-^@M-^],
384 ``af21'', ``af22'', ``af23'', ``af31'', ``af32'', ``af33'', 408 M-bM-^@M-^\af22M-bM-^@M-^], M-bM-^@M-^\af23M-bM-^@M-^], M-bM-^@M-^\af31M-bM-^@M-^], M-bM-^@M-^\af32M-bM-^@M-^], M-bM-^@M-^\af33M-bM-^@M-^], M-bM-^@M-^\af41M-bM-^@M-^], M-bM-^@M-^\af42M-bM-^@M-^], M-bM-^@M-^\af43M-bM-^@M-^],
385 ``af41'', ``af42'', ``af43'', ``cs0'', ``cs1'', ``cs2'', ``cs3'', 409 M-bM-^@M-^\cs0M-bM-^@M-^], M-bM-^@M-^\cs1M-bM-^@M-^], M-bM-^@M-^\cs2M-bM-^@M-^], M-bM-^@M-^\cs3M-bM-^@M-^], M-bM-^@M-^\cs4M-bM-^@M-^], M-bM-^@M-^\cs5M-bM-^@M-^], M-bM-^@M-^\cs6M-bM-^@M-^], M-bM-^@M-^\cs7M-bM-^@M-^], M-bM-^@M-^\efM-bM-^@M-^],
386 ``cs4'', ``cs5'', ``cs6'', ``cs7'', ``ef'', ``lowdelay'', 410 M-bM-^@M-^\lowdelayM-bM-^@M-^], M-bM-^@M-^\throughputM-bM-^@M-^], M-bM-^@M-^\reliabilityM-bM-^@M-^], or a numeric value.
387 ``throughput'', ``reliability'', or a numeric value. This option 411 This option may take one or two arguments, separated by
388 may take one or two arguments, separated by whitespace. If one 412 whitespace. If one argument is specified, it is used as the
389 argument is specified, it is used as the packet class 413 packet class unconditionally. If two values are specified, the
390 unconditionally. If two values are specified, the first is 414 first is automatically selected for interactive sessions and the
391 automatically selected for interactive sessions and the second 415 second for non-interactive sessions. The default is M-bM-^@M-^\lowdelayM-bM-^@M-^]
392 for non-interactive sessions. The default is ``lowdelay'' for 416 for interactive sessions and M-bM-^@M-^\throughputM-bM-^@M-^] for non-interactive
393 interactive sessions and ``throughput'' for non-interactive
394 sessions. 417 sessions.
395 418
396 KbdInteractiveAuthentication 419 KbdInteractiveAuthentication
397 Specifies whether to allow keyboard-interactive authentication. 420 Specifies whether to allow keyboard-interactive authentication.
398 The argument to this keyword must be ``yes'' or ``no''. The 421 The argument to this keyword must be M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The default
399 default is to use whatever value ChallengeResponseAuthentication 422 is to use whatever value ChallengeResponseAuthentication is set
400 is set to (by default ``yes''). 423 to (by default M-bM-^@M-^\yesM-bM-^@M-^]).
401 424
402 KerberosAuthentication 425 KerberosAuthentication
403 Specifies whether the password provided by the user for 426 Specifies whether the password provided by the user for
404 PasswordAuthentication will be validated through the Kerberos 427 PasswordAuthentication will be validated through the Kerberos
405 KDC. To use this option, the server needs a Kerberos servtab 428 KDC. To use this option, the server needs a Kerberos servtab
406 which allows the verification of the KDC's identity. The default 429 which allows the verification of the KDC's identity. The default
407 is ``no''. 430 is M-bM-^@M-^\noM-bM-^@M-^].
408 431
409 KerberosGetAFSToken 432 KerberosGetAFSToken
410 If AFS is active and the user has a Kerberos 5 TGT, attempt to 433 If AFS is active and the user has a Kerberos 5 TGT, attempt to
411 acquire an AFS token before accessing the user's home directory. 434 acquire an AFS token before accessing the user's home directory.
412 The default is ``no''. 435 The default is M-bM-^@M-^\noM-bM-^@M-^].
413 436
414 KerberosOrLocalPasswd 437 KerberosOrLocalPasswd
415 If password authentication through Kerberos fails then the 438 If password authentication through Kerberos fails then the
416 password will be validated via any additional local mechanism 439 password will be validated via any additional local mechanism
417 such as /etc/passwd. The default is ``yes''. 440 such as /etc/passwd. The default is M-bM-^@M-^\yesM-bM-^@M-^].
418 441
419 KerberosTicketCleanup 442 KerberosTicketCleanup
420 Specifies whether to automatically destroy the user's ticket 443 Specifies whether to automatically destroy the user's ticket
421 cache file on logout. The default is ``yes''. 444 cache file on logout. The default is M-bM-^@M-^\yesM-bM-^@M-^].
422 445
423 KexAlgorithms 446 KexAlgorithms
424 Specifies the available KEX (Key Exchange) algorithms. Multiple 447 Specifies the available KEX (Key Exchange) algorithms. Multiple
@@ -441,6 +464,9 @@ DESCRIPTION
441 diffie-hellman-group-exchange-sha256, 464 diffie-hellman-group-exchange-sha256,
442 diffie-hellman-group14-sha1 465 diffie-hellman-group14-sha1
443 466
467 The list of available key exchange algorithms may also be
468 obtained using the -Q option of ssh(1) with an argument of M-bM-^@M-^\kexM-bM-^@M-^].
469
444 KeyRegenerationInterval 470 KeyRegenerationInterval
445 In protocol version 1, the ephemeral server key is automatically 471 In protocol version 1, the ephemeral server key is automatically
446 regenerated after this many seconds (if it has been used). The 472 regenerated after this many seconds (if it has been used). The
@@ -479,9 +505,9 @@ DESCRIPTION
479 MACs Specifies the available MAC (message authentication code) 505 MACs Specifies the available MAC (message authentication code)
480 algorithms. The MAC algorithm is used in protocol version 2 for 506 algorithms. The MAC algorithm is used in protocol version 2 for
481 data integrity protection. Multiple algorithms must be comma- 507 data integrity protection. Multiple algorithms must be comma-
482 separated. The algorithms that contain ``-etm'' calculate the 508 separated. The algorithms that contain M-bM-^@M-^\-etmM-bM-^@M-^] calculate the MAC
483 MAC after encryption (encrypt-then-mac). These are considered 509 after encryption (encrypt-then-mac). These are considered safer
484 safer and their use recommended. The supported MACs are: 510 and their use recommended. The supported MACs are:
485 511
486 hmac-md5 512 hmac-md5
487 hmac-md5-96 513 hmac-md5-96
@@ -509,12 +535,15 @@ DESCRIPTION
509 umac-64@openssh.com,umac-128@openssh.com, 535 umac-64@openssh.com,umac-128@openssh.com,
510 hmac-sha2-256,hmac-sha2-512 536 hmac-sha2-256,hmac-sha2-512
511 537
538 The list of available MAC algorithms may also be obtained using
539 the -Q option of ssh(1) with an argument of M-bM-^@M-^\macM-bM-^@M-^].
540
512 Match Introduces a conditional block. If all of the criteria on the 541 Match Introduces a conditional block. If all of the criteria on the
513 Match line are satisfied, the keywords on the following lines 542 Match line are satisfied, the keywords on the following lines
514 override those set in the global section of the config file, 543 override those set in the global section of the config file,
515 until either another Match line or the end of the file. If a 544 until either another Match line or the end of the file. If a
516 keyword appears in multiple Match blocks that are satisified, 545 keyword appears in multiple Match blocks that are satisfied, only
517 only the first instance of the keyword is applied. 546 the first instance of the keyword is applied.
518 547
519 The arguments to Match are one or more criteria-pattern pairs or 548 The arguments to Match are one or more criteria-pattern pairs or
520 the single token All which matches all criteria. The available 549 the single token All which matches all criteria. The available
@@ -525,25 +554,28 @@ DESCRIPTION
525 554
526 The patterns in an Address criteria may additionally contain 555 The patterns in an Address criteria may additionally contain
527 addresses to match in CIDR address/masklen format, e.g. 556 addresses to match in CIDR address/masklen format, e.g.
528 ``192.0.2.0/24'' or ``3ffe:ffff::/32''. Note that the mask 557 M-bM-^@M-^\192.0.2.0/24M-bM-^@M-^] or M-bM-^@M-^\3ffe:ffff::/32M-bM-^@M-^]. Note that the mask length
529 length provided must be consistent with the address - it is an 558 provided must be consistent with the address - it is an error to
530 error to specify a mask length that is too long for the address 559 specify a mask length that is too long for the address or one
531 or one with bits set in this host portion of the address. For 560 with bits set in this host portion of the address. For example,
532 example, ``192.0.2.0/33'' and ``192.0.2.0/8'' respectively. 561 M-bM-^@M-^\192.0.2.0/33M-bM-^@M-^] and M-bM-^@M-^\192.0.2.0/8M-bM-^@M-^] respectively.
533 562
534 Only a subset of keywords may be used on the lines following a 563 Only a subset of keywords may be used on the lines following a
535 Match keyword. Available keywords are AcceptEnv, 564 Match keyword. Available keywords are AcceptEnv,
536 AllowAgentForwarding, AllowGroups, AllowTcpForwarding, 565 AllowAgentForwarding, AllowGroups, AllowStreamLocalForwarding,
537 AllowUsers, AuthenticationMethods, AuthorizedKeysCommand, 566 AllowTcpForwarding, AllowUsers, AuthenticationMethods,
538 AuthorizedKeysCommandUser, AuthorizedKeysFile, 567 AuthorizedKeysCommand, AuthorizedKeysCommandUser,
539 AuthorizedPrincipalsFile, Banner, ChrootDirectory, DenyGroups, 568 AuthorizedKeysFile, AuthorizedPrincipalsFile, Banner,
540 DenyUsers, ForceCommand, GatewayPorts, GSSAPIAuthentication, 569 ChrootDirectory, DenyGroups, DenyUsers, ForceCommand,
541 HostbasedAuthentication, HostbasedUsesNameFromPacketOnly, 570 GatewayPorts, GSSAPIAuthentication, HostbasedAcceptedKeyTypes,
571 HostbasedAuthentication, HostbasedUsesNameFromPacketOnly, IPQoS,
542 KbdInteractiveAuthentication, KerberosAuthentication, 572 KbdInteractiveAuthentication, KerberosAuthentication,
543 MaxAuthTries, MaxSessions, PasswordAuthentication, 573 MaxAuthTries, MaxSessions, PasswordAuthentication,
544 PermitEmptyPasswords, PermitOpen, PermitRootLogin, PermitTTY, 574 PermitEmptyPasswords, PermitOpen, PermitRootLogin, PermitTTY,
545 PermitTunnel, PermitUserRC, PubkeyAuthentication, RekeyLimit, 575 PermitTunnel, PermitUserRC, PubkeyAcceptedKeyTypes,
546 RhostsRSAAuthentication, RSAAuthentication, X11DisplayOffset, 576 PubkeyAuthentication, RekeyLimit, RevokedKeys,
577 RhostsRSAAuthentication, RSAAuthentication, StreamLocalBindMask,
578 StreamLocalBindUnlink, TrustedUserCAKeys, X11DisplayOffset,
547 X11Forwarding and X11UseLocalHost. 579 X11Forwarding and X11UseLocalHost.
548 580
549 MaxAuthTries 581 MaxAuthTries
@@ -562,21 +594,21 @@ DESCRIPTION
562 expires for a connection. The default is 10:30:100. 594 expires for a connection. The default is 10:30:100.
563 595
564 Alternatively, random early drop can be enabled by specifying the 596 Alternatively, random early drop can be enabled by specifying the
565 three colon separated values ``start:rate:full'' (e.g. 597 three colon separated values M-bM-^@M-^\start:rate:fullM-bM-^@M-^] (e.g. "10:30:60").
566 "10:30:60"). sshd(8) will refuse connection attempts with a 598 sshd(8) will refuse connection attempts with a probability of
567 probability of ``rate/100'' (30%) if there are currently 599 M-bM-^@M-^\rate/100M-bM-^@M-^] (30%) if there are currently M-bM-^@M-^\startM-bM-^@M-^] (10)
568 ``start'' (10) unauthenticated connections. The probability 600 unauthenticated connections. The probability increases linearly
569 increases linearly and all connection attempts are refused if the 601 and all connection attempts are refused if the number of
570 number of unauthenticated connections reaches ``full'' (60). 602 unauthenticated connections reaches M-bM-^@M-^\fullM-bM-^@M-^] (60).
571 603
572 PasswordAuthentication 604 PasswordAuthentication
573 Specifies whether password authentication is allowed. The 605 Specifies whether password authentication is allowed. The
574 default is ``yes''. 606 default is M-bM-^@M-^\yesM-bM-^@M-^].
575 607
576 PermitEmptyPasswords 608 PermitEmptyPasswords
577 When password authentication is allowed, it specifies whether the 609 When password authentication is allowed, it specifies whether the
578 server allows login to accounts with empty password strings. The 610 server allows login to accounts with empty password strings. The
579 default is ``no''. 611 default is M-bM-^@M-^\noM-bM-^@M-^].
580 612
581 PermitOpen 613 PermitOpen
582 Specifies the destinations to which TCP port forwarding is 614 Specifies the destinations to which TCP port forwarding is
@@ -588,47 +620,50 @@ DESCRIPTION
588 PermitOpen [IPv6_addr]:port 620 PermitOpen [IPv6_addr]:port
589 621
590 Multiple forwards may be specified by separating them with 622 Multiple forwards may be specified by separating them with
591 whitespace. An argument of ``any'' can be used to remove all 623 whitespace. An argument of M-bM-^@M-^\anyM-bM-^@M-^] can be used to remove all
592 restrictions and permit any forwarding requests. An argument of 624 restrictions and permit any forwarding requests. An argument of
593 ``none'' can be used to prohibit all forwarding requests. By 625 M-bM-^@M-^\noneM-bM-^@M-^] can be used to prohibit all forwarding requests. By
594 default all port forwarding requests are permitted. 626 default all port forwarding requests are permitted.
595 627
596 PermitRootLogin 628 PermitRootLogin
597 Specifies whether root can log in using ssh(1). The argument 629 Specifies whether root can log in using ssh(1). The argument
598 must be ``yes'', ``without-password'', ``forced-commands-only'', 630 must be M-bM-^@M-^\yesM-bM-^@M-^], M-bM-^@M-^\without-passwordM-bM-^@M-^], M-bM-^@M-^\forced-commands-onlyM-bM-^@M-^], or
599 or ``no''. The default is ``yes''. 631 M-bM-^@M-^\noM-bM-^@M-^]. The default is M-bM-^@M-^\yesM-bM-^@M-^].
600 632
601 If this option is set to ``without-password'', password 633 If this option is set to M-bM-^@M-^\without-passwordM-bM-^@M-^], password
602 authentication is disabled for root. 634 authentication is disabled for root.
603 635
604 If this option is set to ``forced-commands-only'', root login 636 If this option is set to M-bM-^@M-^\forced-commands-onlyM-bM-^@M-^], root login with
605 with public key authentication will be allowed, but only if the 637 public key authentication will be allowed, but only if the
606 command option has been specified (which may be useful for taking 638 command option has been specified (which may be useful for taking
607 remote backups even if root login is normally not allowed). All 639 remote backups even if root login is normally not allowed). All
608 other authentication methods are disabled for root. 640 other authentication methods are disabled for root.
609 641
610 If this option is set to ``no'', root is not allowed to log in. 642 If this option is set to M-bM-^@M-^\noM-bM-^@M-^], root is not allowed to log in.
611 643
612 PermitTunnel 644 PermitTunnel
613 Specifies whether tun(4) device forwarding is allowed. The 645 Specifies whether tun(4) device forwarding is allowed. The
614 argument must be ``yes'', ``point-to-point'' (layer 3), 646 argument must be M-bM-^@M-^\yesM-bM-^@M-^], M-bM-^@M-^\point-to-pointM-bM-^@M-^] (layer 3), M-bM-^@M-^\ethernetM-bM-^@M-^]
615 ``ethernet'' (layer 2), or ``no''. Specifying ``yes'' permits 647 (layer 2), or M-bM-^@M-^\noM-bM-^@M-^]. Specifying M-bM-^@M-^\yesM-bM-^@M-^] permits both
616 both ``point-to-point'' and ``ethernet''. The default is ``no''. 648 M-bM-^@M-^\point-to-pointM-bM-^@M-^] and M-bM-^@M-^\ethernetM-bM-^@M-^]. The default is M-bM-^@M-^\noM-bM-^@M-^].
649
650 Independent of this setting, the permissions of the selected
651 tun(4) device must allow access to the user.
617 652
618 PermitTTY 653 PermitTTY
619 Specifies whether pty(4) allocation is permitted. The default is 654 Specifies whether pty(4) allocation is permitted. The default is
620 ``yes''. 655 M-bM-^@M-^\yesM-bM-^@M-^].
621 656
622 PermitUserEnvironment 657 PermitUserEnvironment
623 Specifies whether ~/.ssh/environment and environment= options in 658 Specifies whether ~/.ssh/environment and environment= options in
624 ~/.ssh/authorized_keys are processed by sshd(8). The default is 659 ~/.ssh/authorized_keys are processed by sshd(8). The default is
625 ``no''. Enabling environment processing may enable users to 660 M-bM-^@M-^\noM-bM-^@M-^]. Enabling environment processing may enable users to bypass
626 bypass access restrictions in some configurations using 661 access restrictions in some configurations using mechanisms such
627 mechanisms such as LD_PRELOAD. 662 as LD_PRELOAD.
628 663
629 PermitUserRC 664 PermitUserRC
630 Specifies whether any ~/.ssh/rc file is executed. The default is 665 Specifies whether any ~/.ssh/rc file is executed. The default is
631 ``yes''. 666 M-bM-^@M-^\yesM-bM-^@M-^].
632 667
633 PidFile 668 PidFile
634 Specifies the file that contains the process ID of the SSH 669 Specifies the file that contains the process ID of the SSH
@@ -641,24 +676,30 @@ DESCRIPTION
641 PrintLastLog 676 PrintLastLog
642 Specifies whether sshd(8) should print the date and time of the 677 Specifies whether sshd(8) should print the date and time of the
643 last user login when a user logs in interactively. The default 678 last user login when a user logs in interactively. The default
644 is ``yes''. 679 is M-bM-^@M-^\yesM-bM-^@M-^].
645 680
646 PrintMotd 681 PrintMotd
647 Specifies whether sshd(8) should print /etc/motd when a user logs 682 Specifies whether sshd(8) should print /etc/motd when a user logs
648 in interactively. (On some systems it is also printed by the 683 in interactively. (On some systems it is also printed by the
649 shell, /etc/profile, or equivalent.) The default is ``yes''. 684 shell, /etc/profile, or equivalent.) The default is M-bM-^@M-^\yesM-bM-^@M-^].
650 685
651 Protocol 686 Protocol
652 Specifies the protocol versions sshd(8) supports. The possible 687 Specifies the protocol versions sshd(8) supports. The possible
653 values are `1' and `2'. Multiple versions must be comma- 688 values are M-bM-^@M-^X1M-bM-^@M-^Y and M-bM-^@M-^X2M-bM-^@M-^Y. Multiple versions must be comma-
654 separated. The default is `2'. Note that the order of the 689 separated. The default is M-bM-^@M-^X2M-bM-^@M-^Y. Note that the order of the
655 protocol list does not indicate preference, because the client 690 protocol list does not indicate preference, because the client
656 selects among multiple protocol versions offered by the server. 691 selects among multiple protocol versions offered by the server.
657 Specifying ``2,1'' is identical to ``1,2''. 692 Specifying M-bM-^@M-^\2,1M-bM-^@M-^] is identical to M-bM-^@M-^\1,2M-bM-^@M-^].
693
694 PubkeyAcceptedKeyTypes
695 Specifies the key types that will be accepted for public key
696 authentication as a comma-separated pattern list. The default
697 M-bM-^@M-^\*M-bM-^@M-^] will allow all key types. The -Q option of ssh(1) may be
698 used to list supported key types.
658 699
659 PubkeyAuthentication 700 PubkeyAuthentication
660 Specifies whether public key authentication is allowed. The 701 Specifies whether public key authentication is allowed. The
661 default is ``yes''. Note that this option applies to protocol 702 default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that this option applies to protocol
662 version 2 only. 703 version 2 only.
663 704
664 RekeyLimit 705 RekeyLimit
@@ -666,12 +707,12 @@ DESCRIPTION
666 before the session key is renegotiated, optionally followed a 707 before the session key is renegotiated, optionally followed a
667 maximum amount of time that may pass before the session key is 708 maximum amount of time that may pass before the session key is
668 renegotiated. The first argument is specified in bytes and may 709 renegotiated. The first argument is specified in bytes and may
669 have a suffix of `K', `M', or `G' to indicate Kilobytes, 710 have a suffix of M-bM-^@M-^XKM-bM-^@M-^Y, M-bM-^@M-^XMM-bM-^@M-^Y, or M-bM-^@M-^XGM-bM-^@M-^Y to indicate Kilobytes,
670 Megabytes, or Gigabytes, respectively. The default is between 711 Megabytes, or Gigabytes, respectively. The default is between
671 `1G' and `4G', depending on the cipher. The optional second 712 M-bM-^@M-^X1GM-bM-^@M-^Y and M-bM-^@M-^X4GM-bM-^@M-^Y, depending on the cipher. The optional second
672 value is specified in seconds and may use any of the units 713 value is specified in seconds and may use any of the units
673 documented in the TIME FORMATS section. The default value for 714 documented in the TIME FORMATS section. The default value for
674 RekeyLimit is ``default none'', which means that rekeying is 715 RekeyLimit is M-bM-^@M-^\default noneM-bM-^@M-^], which means that rekeying is
675 performed after the cipher's default amount of data has been sent 716 performed after the cipher's default amount of data has been sent
676 or received and no time based rekeying is done. This option 717 or received and no time based rekeying is done. This option
677 applies to protocol version 2 only. 718 applies to protocol version 2 only.
@@ -688,12 +729,11 @@ DESCRIPTION
688 RhostsRSAAuthentication 729 RhostsRSAAuthentication
689 Specifies whether rhosts or /etc/hosts.equiv authentication 730 Specifies whether rhosts or /etc/hosts.equiv authentication
690 together with successful RSA host authentication is allowed. The 731 together with successful RSA host authentication is allowed. The
691 default is ``no''. This option applies to protocol version 1 732 default is M-bM-^@M-^\noM-bM-^@M-^]. This option applies to protocol version 1 only.
692 only.
693 733
694 RSAAuthentication 734 RSAAuthentication
695 Specifies whether pure RSA authentication is allowed. The 735 Specifies whether pure RSA authentication is allowed. The
696 default is ``yes''. This option applies to protocol version 1 736 default is M-bM-^@M-^\yesM-bM-^@M-^]. This option applies to protocol version 1
697 only. 737 only.
698 738
699 ServerKeyBits 739 ServerKeyBits
@@ -719,14 +759,14 @@ DESCRIPTION
719 domain socket file. This option is only used for port forwarding 759 domain socket file. This option is only used for port forwarding
720 to a Unix-domain socket file. 760 to a Unix-domain socket file.
721 761
722 The argument must be ``yes'' or ``no''. The default is ``no''. 762 The argument must be M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The default is M-bM-^@M-^\noM-bM-^@M-^].
723 763
724 StrictModes 764 StrictModes
725 Specifies whether sshd(8) should check file modes and ownership 765 Specifies whether sshd(8) should check file modes and ownership
726 of the user's files and home directory before accepting login. 766 of the user's files and home directory before accepting login.
727 This is normally desirable because novices sometimes accidentally 767 This is normally desirable because novices sometimes accidentally
728 leave their directory or files world-writable. The default is 768 leave their directory or files world-writable. The default is
729 ``yes''. Note that this does not apply to ChrootDirectory, whose 769 M-bM-^@M-^\yesM-bM-^@M-^]. Note that this does not apply to ChrootDirectory, whose
730 permissions and ownership are checked unconditionally. 770 permissions and ownership are checked unconditionally.
731 771
732 Subsystem 772 Subsystem
@@ -734,11 +774,11 @@ DESCRIPTION
734 Arguments should be a subsystem name and a command (with optional 774 Arguments should be a subsystem name and a command (with optional
735 arguments) to execute upon subsystem request. 775 arguments) to execute upon subsystem request.
736 776
737 The command sftp-server(8) implements the ``sftp'' file transfer 777 The command sftp-server(8) implements the M-bM-^@M-^\sftpM-bM-^@M-^] file transfer
738 subsystem. 778 subsystem.
739 779
740 Alternately the name ``internal-sftp'' implements an in-process 780 Alternately the name M-bM-^@M-^\internal-sftpM-bM-^@M-^] implements an in-process
741 ``sftp'' server. This may simplify configurations using 781 M-bM-^@M-^\sftpM-bM-^@M-^] server. This may simplify configurations using
742 ChrootDirectory to force a different filesystem root on clients. 782 ChrootDirectory to force a different filesystem root on clients.
743 783
744 By default no subsystems are defined. Note that this option 784 By default no subsystems are defined. Note that this option
@@ -757,21 +797,21 @@ DESCRIPTION
757 this means that connections will die if the route is down 797 this means that connections will die if the route is down
758 temporarily, and some people find it annoying. On the other 798 temporarily, and some people find it annoying. On the other
759 hand, if TCP keepalives are not sent, sessions may hang 799 hand, if TCP keepalives are not sent, sessions may hang
760 indefinitely on the server, leaving ``ghost'' users and consuming 800 indefinitely on the server, leaving M-bM-^@M-^\ghostM-bM-^@M-^] users and consuming
761 server resources. 801 server resources.
762 802
763 The default is ``yes'' (to send TCP keepalive messages), and the 803 The default is M-bM-^@M-^\yesM-bM-^@M-^] (to send TCP keepalive messages), and the
764 server will notice if the network goes down or the client host 804 server will notice if the network goes down or the client host
765 crashes. This avoids infinitely hanging sessions. 805 crashes. This avoids infinitely hanging sessions.
766 806
767 To disable TCP keepalive messages, the value should be set to 807 To disable TCP keepalive messages, the value should be set to
768 ``no''. 808 M-bM-^@M-^\noM-bM-^@M-^].
769 809
770 TrustedUserCAKeys 810 TrustedUserCAKeys
771 Specifies a file containing public keys of certificate 811 Specifies a file containing public keys of certificate
772 authorities that are trusted to sign user certificates for 812 authorities that are trusted to sign user certificates for
773 authentication. Keys are listed one per line; empty lines and 813 authentication. Keys are listed one per line; empty lines and
774 comments starting with `#' are allowed. If a certificate is 814 comments starting with M-bM-^@M-^X#M-bM-^@M-^Y are allowed. If a certificate is
775 presented for authentication and has its signing CA key listed in 815 presented for authentication and has its signing CA key listed in
776 this file, then it may be used for authentication for any user 816 this file, then it may be used for authentication for any user
777 listed in the certificate's principals list. Note that 817 listed in the certificate's principals list. Note that
@@ -781,18 +821,18 @@ DESCRIPTION
781 821
782 UseDNS Specifies whether sshd(8) should look up the remote host name and 822 UseDNS Specifies whether sshd(8) should look up the remote host name and
783 check that the resolved host name for the remote IP address maps 823 check that the resolved host name for the remote IP address maps
784 back to the very same IP address. The default is ``yes''. 824 back to the very same IP address. The default is M-bM-^@M-^\noM-bM-^@M-^].
785 825
786 UseLogin 826 UseLogin
787 Specifies whether login(1) is used for interactive login 827 Specifies whether login(1) is used for interactive login
788 sessions. The default is ``no''. Note that login(1) is never 828 sessions. The default is M-bM-^@M-^\noM-bM-^@M-^]. Note that login(1) is never used
789 used for remote command execution. Note also, that if this is 829 for remote command execution. Note also, that if this is
790 enabled, X11Forwarding will be disabled because login(1) does not 830 enabled, X11Forwarding will be disabled because login(1) does not
791 know how to handle xauth(1) cookies. If UsePrivilegeSeparation 831 know how to handle xauth(1) cookies. If UsePrivilegeSeparation
792 is specified, it will be disabled after authentication. 832 is specified, it will be disabled after authentication.
793 833
794 UsePAM Enables the Pluggable Authentication Module interface. If set to 834 UsePAM Enables the Pluggable Authentication Module interface. If set to
795 ``yes'' this will enable PAM authentication using 835 M-bM-^@M-^\yesM-bM-^@M-^] this will enable PAM authentication using
796 ChallengeResponseAuthentication and PasswordAuthentication in 836 ChallengeResponseAuthentication and PasswordAuthentication in
797 addition to PAM account and session module processing for all 837 addition to PAM account and session module processing for all
798 authentication types. 838 authentication types.
@@ -802,7 +842,7 @@ DESCRIPTION
802 either PasswordAuthentication or ChallengeResponseAuthentication. 842 either PasswordAuthentication or ChallengeResponseAuthentication.
803 843
804 If UsePAM is enabled, you will not be able to run sshd(8) as a 844 If UsePAM is enabled, you will not be able to run sshd(8) as a
805 non-root user. The default is ``no''. 845 non-root user. The default is M-bM-^@M-^\noM-bM-^@M-^].
806 846
807 UsePrivilegeSeparation 847 UsePrivilegeSeparation
808 Specifies whether sshd(8) separates privileges by creating an 848 Specifies whether sshd(8) separates privileges by creating an
@@ -811,14 +851,14 @@ DESCRIPTION
811 that has the privilege of the authenticated user. The goal of 851 that has the privilege of the authenticated user. The goal of
812 privilege separation is to prevent privilege escalation by 852 privilege separation is to prevent privilege escalation by
813 containing any corruption within the unprivileged processes. The 853 containing any corruption within the unprivileged processes. The
814 default is ``yes''. If UsePrivilegeSeparation is set to 854 default is M-bM-^@M-^\yesM-bM-^@M-^]. If UsePrivilegeSeparation is set to M-bM-^@M-^\sandboxM-bM-^@M-^]
815 ``sandbox'' then the pre-authentication unprivileged process is 855 then the pre-authentication unprivileged process is subject to
816 subject to additional restrictions. 856 additional restrictions.
817 857
818 VersionAddendum 858 VersionAddendum
819 Optionally specifies additional text to append to the SSH 859 Optionally specifies additional text to append to the SSH
820 protocol banner sent by the server upon connection. The default 860 protocol banner sent by the server upon connection. The default
821 is ``none''. 861 is M-bM-^@M-^\noneM-bM-^@M-^].
822 862
823 X11DisplayOffset 863 X11DisplayOffset
824 Specifies the first display number available for sshd(8)'s X11 864 Specifies the first display number available for sshd(8)'s X11
@@ -827,7 +867,7 @@ DESCRIPTION
827 867
828 X11Forwarding 868 X11Forwarding
829 Specifies whether X11 forwarding is permitted. The argument must 869 Specifies whether X11 forwarding is permitted. The argument must
830 be ``yes'' or ``no''. The default is ``no''. 870 be M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The default is M-bM-^@M-^\noM-bM-^@M-^].
831 871
832 When X11 forwarding is enabled, there may be additional exposure 872 When X11 forwarding is enabled, there may be additional exposure
833 to the server and to client displays if the sshd(8) proxy display 873 to the server and to client displays if the sshd(8) proxy display
@@ -841,7 +881,7 @@ DESCRIPTION
841 ssh_config(5)). A system administrator may have a stance in 881 ssh_config(5)). A system administrator may have a stance in
842 which they want to protect clients that may expose themselves to 882 which they want to protect clients that may expose themselves to
843 attack by unwittingly requesting X11 forwarding, which can 883 attack by unwittingly requesting X11 forwarding, which can
844 warrant a ``no'' setting. 884 warrant a M-bM-^@M-^\noM-bM-^@M-^] setting.
845 885
846 Note that disabling X11 forwarding does not prevent users from 886 Note that disabling X11 forwarding does not prevent users from
847 forwarding X11 traffic, as users can always install their own 887 forwarding X11 traffic, as users can always install their own
@@ -853,12 +893,12 @@ DESCRIPTION
853 to the loopback address or to the wildcard address. By default, 893 to the loopback address or to the wildcard address. By default,
854 sshd binds the forwarding server to the loopback address and sets 894 sshd binds the forwarding server to the loopback address and sets
855 the hostname part of the DISPLAY environment variable to 895 the hostname part of the DISPLAY environment variable to
856 ``localhost''. This prevents remote hosts from connecting to the 896 M-bM-^@M-^\localhostM-bM-^@M-^]. This prevents remote hosts from connecting to the
857 proxy display. However, some older X11 clients may not function 897 proxy display. However, some older X11 clients may not function
858 with this configuration. X11UseLocalhost may be set to ``no'' to 898 with this configuration. X11UseLocalhost may be set to M-bM-^@M-^\noM-bM-^@M-^] to
859 specify that the forwarding server should be bound to the 899 specify that the forwarding server should be bound to the
860 wildcard address. The argument must be ``yes'' or ``no''. The 900 wildcard address. The argument must be M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The
861 default is ``yes''. 901 default is M-bM-^@M-^\yesM-bM-^@M-^].
862 902
863 XAuthLocation 903 XAuthLocation
864 Specifies the full pathname of the xauth(1) program. The default 904 Specifies the full pathname of the xauth(1) program. The default
@@ -870,7 +910,7 @@ TIME FORMATS
870 time[qualifier], where time is a positive integer value and qualifier is 910 time[qualifier], where time is a positive integer value and qualifier is
871 one of the following: 911 one of the following:
872 912
873 <none> seconds 913 M-bM-^_M-(noneM-bM-^_M-) seconds
874 s | S seconds 914 s | S seconds
875 m | M minutes 915 m | M minutes
876 h | H hours 916 h | H hours
@@ -903,4 +943,4 @@ AUTHORS
903 versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support 943 versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support
904 for privilege separation. 944 for privilege separation.
905 945
906OpenBSD 5.6 July 28, 2014 OpenBSD 5.6 946OpenBSD 5.7 February 20, 2015 OpenBSD 5.7