1SSHD_CONFIG(5) BSD File Formats Manual SSHD_CONFIG(5)
2
4 sshd_config — OpenSSH daemon configuration file
5
7 sshd(8) reads configuration data from /etc/gsissh/sshd_config (or the
8 file specified with -f on the command line). The file contains keyword-
9 argument pairs, one per line. For each keyword, the first obtained value
10 will be used. Lines starting with ‘#’ and empty lines are interpreted as
11 comments. Arguments may optionally be enclosed in double quotes (") in
12 order to represent arguments containing spaces.
13 The possible keywords and their meanings are as follows (note that key‐
15 words are case-insensitive and arguments are case-sensitive):
16 AcceptEnv
18 Specifies what environment variables sent by the client will be
19 copied into the session's environ(7). See SendEnv and SetEnv in
20 ssh_config(5) for how to configure the client. The TERM environ‐
21 ment variable is always accepted whenever the client requests a
22 pseudo-terminal as it is required by the protocol. Variables are
23 specified by name, which may contain the wildcard characters ‘*’
24 and ‘?’. Multiple environment variables may be separated by
25 whitespace or spread across multiple AcceptEnv directives. Be
26 warned that some environment variables could be used to bypass
27 restricted user environments. For this reason, care should be
28 taken in the use of this directive. The default is not to accept
29 any environment variables.
30 AddressFamily
32 Specifies which address family should be used by sshd(8). Valid
33 arguments are any (the default), inet (use IPv4 only), or inet6
34 (use IPv6 only).
35 AllowAgentForwarding
37 Specifies whether ssh-agent(1) forwarding is permitted. The de‐
38 fault is yes. Note that disabling agent forwarding does not im‐
39 prove security unless users are also denied shell access, as they
40 can always install their own forwarders.
41 AllowGroups
43 This keyword can be followed by a list of group name patterns,
44 separated by spaces. If specified, login is allowed only for
45 users whose primary group or supplementary group list matches one
46 of the patterns. Only group names are valid; a numerical group
47 ID is not recognized. By default, login is allowed for all
48 groups. The allow/deny groups directives are processed in the
49 following order: DenyGroups, AllowGroups.
50 See PATTERNS in ssh_config(5) for more information on patterns.
52 AllowStreamLocalForwarding
54 Specifies whether StreamLocal (Unix-domain socket) forwarding is
55 permitted. The available options are yes (the default) or all to
56 allow StreamLocal forwarding, no to prevent all StreamLocal for‐
57 warding, local to allow local (from the perspective of ssh(1))
58 forwarding only or remote to allow remote forwarding only. Note
59 that disabling StreamLocal forwarding does not improve security
60 unless users are also denied shell access, as they can always in‐
61 stall their own forwarders.
62 AllowTcpForwarding
64 Specifies whether TCP forwarding is permitted. The available op‐
65 tions are yes (the default) or all to allow TCP forwarding, no to
66 prevent all TCP forwarding, local to allow local (from the per‐
67 spective of ssh(1)) forwarding only or remote to allow remote
68 forwarding only. Note that disabling TCP forwarding does not im‐
69 prove security unless users are also denied shell access, as they
70 can always install their own forwarders.
71 AllowUsers
73 This keyword can be followed by a list of user name patterns,
74 separated by spaces. If specified, login is allowed only for
75 user names that match one of the patterns. Only user names are
76 valid; a numerical user ID is not recognized. By default, login
77 is allowed for all users. If the pattern takes the form
78 USER@HOST then USER and HOST are separately checked, restricting
79 logins to particular users from particular hosts. HOST criteria
80 may additionally contain addresses to match in CIDR ad‐
81 dress/masklen format. The allow/deny users directives are pro‐
82 cessed in the following order: DenyUsers, AllowUsers.
83 See PATTERNS in ssh_config(5) for more information on patterns.
85 AuthenticationMethods
87 Specifies the authentication methods that must be successfully
88 completed for a user to be granted access. This option must be
89 followed by one or more lists of comma-separated authentication
90 method names, or by the single string any to indicate the default
91 behaviour of accepting any single authentication method. If the
92 default is overridden, then successful authentication requires
93 completion of every method in at least one of these lists.
94 For example, "publickey,password publickey,keyboard-interactive"
96 would require the user to complete public key authentication,
97 followed by either password or keyboard interactive authentica‐
98 tion. Only methods that are next in one or more lists are of‐
99 fered at each stage, so for this example it would not be possible
100 to attempt password or keyboard-interactive authentication before
101 public key.
102 For keyboard interactive authentication it is also possible to
104 restrict authentication to a specific device by appending a colon
105 followed by the device identifier bsdauth or pam. depending on
106 the server configuration. For example,
107 "keyboard-interactive:bsdauth" would restrict keyboard interac‐
108 tive authentication to the bsdauth device.
109 If the publickey method is listed more than once, sshd(8) veri‐
111 fies that keys that have been used successfully are not reused
112 for subsequent authentications. For example,
113 "publickey,publickey" requires successful authentication using
114 two different public keys.
115 Note that each authentication method listed should also be ex‐
117 plicitly enabled in the configuration.
118 The available authentication methods are: "gssapi-with-mic",
120 "hostbased", "keyboard-interactive", "none" (used for access to
121 password-less accounts when PermitEmptyPasswords is enabled),
122 "password" and "publickey".
123 AuthorizedKeysCommand
125 Specifies a program to be used to look up the user's public keys.
126 The program must be owned by root, not writable by group or oth‐
127 ers and specified by an absolute path. Arguments to
128 AuthorizedKeysCommand accept the tokens described in the TOKENS
129 section. If no arguments are specified then the username of the
130 target user is used.
131 The program should produce on standard output zero or more lines
133 of authorized_keys output (see AUTHORIZED_KEYS in sshd(8)).
134 AuthorizedKeysCommand is tried after the usual AuthorizedKeysFile
135 files and will not be executed if a matching key is found there.
136 By default, no AuthorizedKeysCommand is run.
137 AuthorizedKeysCommandUser
139 Specifies the user under whose account the AuthorizedKeysCommand
140 is run. It is recommended to use a dedicated user that has no
141 other role on the host than running authorized keys commands. If
142 AuthorizedKeysCommand is specified but AuthorizedKeysCommandUser
143 is not, then sshd(8) will refuse to start.
144 AuthorizedKeysFile
146 Specifies the file that contains the public keys used for user
147 authentication. The format is described in the AUTHORIZED_KEYS
148 FILE FORMAT section of sshd(8). Arguments to AuthorizedKeysFile
149 accept the tokens described in the TOKENS section. After expan‐
150 sion, AuthorizedKeysFile is taken to be an absolute path or one
151 relative to the user's home directory. Multiple files may be
152 listed, separated by whitespace. Alternately this option may be
153 set to none to skip checking for user keys in files. The default
154 is ".ssh/authorized_keys .ssh/authorized_keys2".
155 AuthorizedPrincipalsCommand
157 Specifies a program to be used to generate the list of allowed
158 certificate principals as per AuthorizedPrincipalsFile. The pro‐
159 gram must be owned by root, not writable by group or others and
160 specified by an absolute path. Arguments to
161 AuthorizedPrincipalsCommand accept the tokens described in the
162 TOKENS section. If no arguments are specified then the username
163 of the target user is used.
164 The program should produce on standard output zero or more lines
166 of AuthorizedPrincipalsFile output. If either
167 AuthorizedPrincipalsCommand or AuthorizedPrincipalsFile is speci‐
168 fied, then certificates offered by the client for authentication
169 must contain a principal that is listed. By default, no
170 AuthorizedPrincipalsCommand is run.
171 AuthorizedPrincipalsCommandUser
173 Specifies the user under whose account the
174 AuthorizedPrincipalsCommand is run. It is recommended to use a
175 dedicated user that has no other role on the host than running
176 authorized principals commands. If AuthorizedPrincipalsCommand
177 is specified but AuthorizedPrincipalsCommandUser is not, then
178 sshd(8) will refuse to start.
179 AuthorizedPrincipalsFile
181 Specifies a file that lists principal names that are accepted for
182 certificate authentication. When using certificates signed by a
183 key listed in TrustedUserCAKeys, this file lists names, one of
184 which must appear in the certificate for it to be accepted for
185 authentication. Names are listed one per line preceded by key
186 options (as described in AUTHORIZED_KEYS FILE FORMAT in sshd(8)).
187 Empty lines and comments starting with ‘#’ are ignored.
188 Arguments to AuthorizedPrincipalsFile accept the tokens described
190 in the TOKENS section. After expansion, AuthorizedPrincipalsFile
191 is taken to be an absolute path or one relative to the user's
192 home directory. The default is none, i.e. not to use a princi‐
193 pals file – in this case, the username of the user must appear in
194 a certificate's principals list for it to be accepted.
195 Note that AuthorizedPrincipalsFile is only used when authentica‐
197 tion proceeds using a CA listed in TrustedUserCAKeys and is not
198 consulted for certification authorities trusted via
199 ~/.ssh/authorized_keys, though the principals= key option offers
200 a similar facility (see sshd(8) for details).
201 Banner The contents of the specified file are sent to the remote user
203 before authentication is allowed. If the argument is none then
204 no banner is displayed. By default, no banner is displayed.
205 CASignatureAlgorithms
207 The default is handled system-wide by crypto-policies(7). To see
208 the defaults and how to modify this default, see manual page
209 update-crypto-policies(8).
210 Specifies which algorithms are allowed for signing of certifi‐
212 cates by certificate authorities (CAs). Certificates signed us‐
213 ing other algorithms will not be accepted for public key or host-
214 based authentication.
215 ChallengeResponseAuthentication
217 Specifies whether challenge-response authentication is allowed
218 (e.g. via PAM or through authentication styles supported in
219 login.conf(5)) The default is yes.
220 ChrootDirectory
222 Specifies the pathname of a directory to chroot(2) to after au‐
223 thentication. At session startup sshd(8) checks that all compo‐
224 nents of the pathname are root-owned directories which are not
225 writable by any other user or group. After the chroot, sshd(8)
226 changes the working directory to the user's home directory. Ar‐
227 guments to ChrootDirectory accept the tokens described in the
228 TOKENS section.
229 The ChrootDirectory must contain the necessary files and directo‐
231 ries to support the user's session. For an interactive session
232 this requires at least a shell, typically sh(1), and basic /dev
233 nodes such as null(4), zero(4), stdin(4), stdout(4), stderr(4),
234 and tty(4) devices. For file transfer sessions using SFTP no ad‐
235 ditional configuration of the environment is necessary if the in-
236 process sftp-server is used, though sessions which use logging
237 may require /dev/log inside the chroot directory on some operat‐
238 ing systems (see sftp-server(8) for details).
239 For safety, it is very important that the directory hierarchy be
241 prevented from modification by other processes on the system (es‐
242 pecially those outside the jail). Misconfiguration can lead to
243 unsafe environments which sshd(8) cannot detect.
244 The default is none, indicating not to chroot(2).
246 Ciphers
248 The default is handled system-wide by crypto-policies(7). To see
249 the defaults and how to modify this default, see manual page
250 update-crypto-policies(8).
251 Specifies the ciphers allowed. Multiple ciphers must be comma-
253 separated. If the specified list begins with a ‘+’ character,
254 then the specified ciphers will be appended to the built-in
255 openssh default set instead of replacing them. If the specified
256 list begins with a ‘-’ character, then the specified ciphers (in‐
257 cluding wildcards) will be removed from the built-in openssh de‐
258 fault set instead of replacing them. If the specified list be‐
259 gins with a ‘^’ character, then the specified ciphers will be
260 placed at the head of the built-in openssh default set.
261 The supported ciphers are:
263 3des-cbc
265 aes128-cbc
266 aes192-cbc
267 aes256-cbc
268 aes128-ctr
269 aes192-ctr
270 aes256-ctr
271 aes128-gcm@openssh.com
272 aes256-gcm@openssh.com
273 chacha20-poly1305@openssh.com
274 The list of available ciphers may also be obtained using "ssh -Q
276 cipher".
277 ClientAliveCountMax
279 Sets the number of client alive messages which may be sent with‐
280 out sshd(8) receiving any messages back from the client. If this
281 threshold is reached while client alive messages are being sent,
282 sshd will disconnect the client, terminating the session. It is
283 important to note that the use of client alive messages is very
284 different from TCPKeepAlive. The client alive messages are sent
285 through the encrypted channel and therefore will not be spoofa‐
286 ble. The TCP keepalive option enabled by TCPKeepAlive is spoofa‐
287 ble. The client alive mechanism is valuable when the client or
288 server depend on knowing when a connection has become unrespon‐
289 sive.
290 The default value is 3. If ClientAliveInterval is set to 15, and
292 ClientAliveCountMax is left at the default, unresponsive SSH
293 clients will be disconnected after approximately 45 seconds.
294 Setting a zero ClientAliveCountMax disables connection termina‐
295 tion.
296 ClientAliveInterval
298 Sets a timeout interval in seconds after which if no data has
299 been received from the client, sshd(8) will send a message
300 through the encrypted channel to request a response from the
301 client. The default is 0, indicating that these messages will
302 not be sent to the client.
303 Compression
305 Specifies whether compression is enabled after the user has au‐
306 thenticated successfully. The argument must be yes, delayed (a
307 legacy synonym for yes) or no. The default is yes.
308 DenyGroups
310 This keyword can be followed by a list of group name patterns,
311 separated by spaces. Login is disallowed for users whose primary
312 group or supplementary group list matches one of the patterns.
313 Only group names are valid; a numerical group ID is not recog‐
314 nized. By default, login is allowed for all groups. The al‐
315 low/deny groups directives are processed in the following order:
316 DenyGroups, AllowGroups.
317 See PATTERNS in ssh_config(5) for more information on patterns.
319 DenyUsers
321 This keyword can be followed by a list of user name patterns,
322 separated by spaces. Login is disallowed for user names that
323 match one of the patterns. Only user names are valid; a numeri‐
324 cal user ID is not recognized. By default, login is allowed for
325 all users. If the pattern takes the form USER@HOST then USER and
326 HOST are separately checked, restricting logins to particular
327 users from particular hosts. HOST criteria may additionally con‐
328 tain addresses to match in CIDR address/masklen format. The al‐
329 low/deny users directives are processed in the following order:
330 DenyUsers, AllowUsers.
331 See PATTERNS in ssh_config(5) for more information on patterns.
333 DisableForwarding
335 Disables all forwarding features, including X11, ssh-agent(1),
336 TCP and StreamLocal. This option overrides all other forwarding-
337 related options and may simplify restricted configurations.
338 ExposeAuthInfo
340 Writes a temporary file containing a list of authentication meth‐
341 ods and public credentials (e.g. keys) used to authenticate the
342 user. The location of the file is exposed to the user session
343 through the SSH_USER_AUTH environment variable. The default is
344 no.
345 FingerprintHash
347 Specifies the hash algorithm used when logging key fingerprints.
348 Valid options are: md5 and sha256. The default is sha256.
349 ForceCommand
351 Forces the execution of the command specified by ForceCommand,
352 ignoring any command supplied by the client and ~/.ssh/rc if
353 present. The command is invoked by using the user's login shell
354 with the -c option. This applies to shell, command, or subsystem
355 execution. It is most useful inside a Match block. The command
356 originally supplied by the client is available in the
357 SSH_ORIGINAL_COMMAND environment variable. Specifying a command
358 of internal-sftp will force the use of an in-process SFTP server
359 that requires no support files when used with ChrootDirectory.
360 The default is none.
361 GatewayPorts
363 Specifies whether remote hosts are allowed to connect to ports
364 forwarded for the client. By default, sshd(8) binds remote port
365 forwardings to the loopback address. This prevents other remote
366 hosts from connecting to forwarded ports. GatewayPorts can be
367 used to specify that sshd should allow remote port forwardings to
368 bind to non-loopback addresses, thus allowing other hosts to con‐
369 nect. The argument may be no to force remote port forwardings to
370 be available to the local host only, yes to force remote port
371 forwardings to bind to the wildcard address, or clientspecified
372 to allow the client to select the address to which the forwarding
373 is bound. The default is no.
374 GSIAllowLimitedProxy
376 Specifies whether to accept limited proxy credentials for authen‐
377 tication. The default is no.
378 GSSAPIAuthentication
380 Specifies whether user authentication based on GSSAPI is allowed.
381 The default is yes.
382 GSSAPICleanupCredentials
384 Specifies whether to automatically destroy the user's credentials
385 cache on logout. The default is yes.
386 GSSAPICredentialsPath
388 If specified, the delegated GSSAPI credential is stored in the
389 given path, overwriting any existing credentials. Paths can be
390 specified with syntax similar to the AuthorizedKeysFile option
391 (i.e., accepting %h and %u tokens). When using this option, set‐
392 ting 'GssapiCleanupCredentials no' is recommended, so logging out
393 of one session doesn't remove the credentials in use by another
394 session of the same user. Currently only implemented for the GSI
395 mechanism.
396 GSSAPIDelegateCredentials
398 Specifies whether delegated credentials are stored in the user's
399 environment. The default is yes.
400 GSSAPIEnablek5users
402 Specifies whether to look at .k5users file for GSSAPI authentica‐
403 tion access control. Further details are described in ksu(1).
404 The default is no.
405 GSSAPIKeyExchange
407 Specifies whether key exchange based on GSSAPI is allowed. GSSAPI
408 key exchange doesn't rely on ssh keys to verify host identity.
409 The default is yes.
410 GSSAPIStrictAcceptorCheck
412 Determines whether to be strict about the identity of the GSSAPI
413 acceptor a client authenticates against. If set to yes then the
414 client must authenticate against the host service on the current
415 hostname. If set to no then the client may authenticate against
416 any service key stored in the machine's default store. This fa‐
417 cility is provided to assist with operation on multi homed ma‐
418 chines. The default is yes.
419 GSSAPIStoreCredentialsOnRekey
421 Controls whether the user's GSSAPI credentials should be updated
422 following a successful connection rekeying. This option can be
423 used to accepted renewed or updated credentials from a compatible
424 client. The default is “no”.
425 For this to work GSSAPIKeyExchange needs to be enabled in the
427 server and also used by the client.
428 GSSAPIKexAlgorithms
430 The default is handled system-wide by crypto-policies(7). To see
431 the defaults and how to modify this default, see manual page
432 update-crypto-policies(8).
433 The list of key exchange algorithms that are accepted by GSSAPI
435 key exchange. Possible values are
436 gss-gex-sha1-
438 gss-group1-sha1-
439 gss-group14-sha1-
440 gss-group14-sha256-
441 gss-group16-sha512-
442 gss-nistp256-sha256-
443 gss-curve25519-sha256-
444 This option only applies to connections using GSSAPI.
445 HostbasedAcceptedAlgorithms
447 Specifies the signature algorithms that will be accepted for
448 hostbased authentication as a list of comma-separated patterns.
449 Alternately if the specified list begins with a ‘+’ character,
450 then the specified signature algorithms will be appended to the
451 default set instead of replacing them. If the specified list be‐
452 gins with a ‘-’ character, then the specified signature algo‐
453 rithms (including wildcards) will be removed from the default set
454 instead of replacing them. If the specified list begins with a
455 ‘^’ character, then the specified signature algorithms will be
456 placed at the head of the default set. The default for this op‐
457 tion is:
458 ssh-ed25519-cert-v01@openssh.com,
460 ecdsa-sha2-nistp256-cert-v01@openssh.com,
461 ecdsa-sha2-nistp384-cert-v01@openssh.com,
462 ecdsa-sha2-nistp521-cert-v01@openssh.com,
463 sk-ssh-ed25519-cert-v01@openssh.com,
464 sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
465 rsa-sha2-512-cert-v01@openssh.com,
466 rsa-sha2-256-cert-v01@openssh.com,
467 ssh-rsa-cert-v01@openssh.com,
468 ssh-ed25519,
469 ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
470 sk-ssh-ed25519@openssh.com,
471 sk-ecdsa-sha2-nistp256@openssh.com,
472 rsa-sha2-512,rsa-sha2-256,ssh-rsa
473 The list of available signature algorithms may also be obtained
475 using "ssh -Q HostbasedAcceptedAlgorithms". This was formerly
476 named HostbasedAcceptedKeyTypes.
477 HostbasedAuthentication
479 Specifies whether rhosts or /etc/hosts.equiv authentication to‐
480 gether with successful public key client host authentication is
481 allowed (host-based authentication). The default is no.
482 HostbasedUsesNameFromPacketOnly
484 Specifies whether or not the server will attempt to perform a re‐
485 verse name lookup when matching the name in the ~/.shosts,
486 ~/.rhosts, and /etc/hosts.equiv files during
487 HostbasedAuthentication. A setting of yes means that sshd(8)
488 uses the name supplied by the client rather than attempting to
489 resolve the name from the TCP connection itself. The default is
490 no.
491 HostCertificate
493 Specifies a file containing a public host certificate. The cer‐
494 tificate's public key must match a private host key already spec‐
495 ified by HostKey. The default behaviour of sshd(8) is not to
496 load any certificates.
497 HostKey
499 Specifies a file containing a private host key used by SSH. The
500 defaults are /etc/gsissh/ssh_host_ecdsa_key,
501 /etc/gsissh/ssh_host_ed25519_key and
502 /etc/gsissh/ssh_host_rsa_key.
503 Note that sshd(8) will refuse to use a file if it is group/world-
505 accessible and that the HostKeyAlgorithms option restricts which
506 of the keys are actually used by sshd(8).
507 It is possible to have multiple host key files. It is also pos‐
509 sible to specify public host key files instead. In this case op‐
510 erations on the private key will be delegated to an ssh-agent(1).
511 HostKeyAgent
513 Identifies the UNIX-domain socket used to communicate with an
514 agent that has access to the private host keys. If the string
515 "SSH_AUTH_SOCK" is specified, the location of the socket will be
516 read from the SSH_AUTH_SOCK environment variable.
517 HostKeyAlgorithms
519 The default is handled system-wide by crypto-policies(7). To see
520 the defaults and how to modify this default, see manual page
521 update-crypto-policies(8).
522 Specifies the host key signature algorithms that the server of‐
524 fers. The list of available signature algorithms may also be ob‐
525 tained using "ssh -Q HostKeyAlgorithms".
526 IgnoreRhosts
528 Specifies whether to ignore per-user .rhosts and .shosts files
529 during HostbasedAuthentication. The system-wide /etc/hosts.equiv
530 and /etc/gsissh/shosts.equiv are still used regardless of this
531 setting.
532 Accepted values are yes (the default) to ignore all per-user
534 files, shosts-only to allow the use of .shosts but to ignore
535 .rhosts or no to allow both .shosts and rhosts.
536 IgnoreUserKnownHosts
538 Specifies whether sshd(8) should ignore the user's
539 ~/.ssh/known_hosts during HostbasedAuthentication and use only
540 the system-wide known hosts file /etc/ssh/known_hosts. The de‐
541 fault is “no”.
542 Include
544 Include the specified configuration file(s). Multiple pathnames
545 may be specified and each pathname may contain glob(7) wildcards
546 that will be expanded and processed in lexical order. Files
547 without absolute paths are assumed to be in /etc/ssh. An Include
548 directive may appear inside a Match block to perform conditional
549 inclusion.
550 IPQoS Specifies the IPv4 type-of-service or DSCP class for the connec‐
552 tion. Accepted values are af11, af12, af13, af21, af22, af23,
553 af31, af32, af33, af41, af42, af43, cs0, cs1, cs2, cs3, cs4, cs5,
554 cs6, cs7, ef, le, lowdelay, throughput, reliability, a numeric
555 value, or none to use the operating system default. This option
556 may take one or two arguments, separated by whitespace. If one
557 argument is specified, it is used as the packet class uncondi‐
558 tionally. If two values are specified, the first is automati‐
559 cally selected for interactive sessions and the second for non-
560 interactive sessions. The default is af21 (Low-Latency Data) for
561 interactive sessions and cs1 (Lower Effort) for non-interactive
562 sessions.
563 KbdInteractiveAuthentication
565 Specifies whether to allow keyboard-interactive authentication.
566 The argument to this keyword must be yes or no. The default is
567 to use whatever value ChallengeResponseAuthentication is set to
568 (by default yes).
569 KerberosAuthentication
571 Specifies whether the password provided by the user for
572 PasswordAuthentication will be validated through the Kerberos
573 KDC. To use this option, the server needs a Kerberos servtab
574 which allows the verification of the KDC's identity. The default
575 is no.
576 KerberosGetAFSToken
578 If AFS is active and the user has a Kerberos 5 TGT, attempt to
579 acquire an AFS token before accessing the user's home directory.
580 The default is no.
581 KerberosOrLocalPasswd
583 If password authentication through Kerberos fails then the pass‐
584 word will be validated via any additional local mechanism such as
585 /etc/passwd. The default is yes.
586 KerberosTicketCleanup
588 Specifies whether to automatically destroy the user's ticket
589 cache file on logout. The default is yes.
590 KerberosUniqueCCache
592 Specifies whether to store the acquired tickets in the per-ses‐
593 sion credential cache under /tmp/ or whether to use per-user cre‐
594 dential cache as configured in /etc/krb5.conf. The default value
595 no can lead to overwriting previous tickets by subseqent connec‐
596 tions to the same user account.
597 KerberosUseKuserok
599 Specifies whether to look at .k5login file for user's aliases.
600 The default is yes.
601 KexAlgorithms
603 The default is handled system-wide by crypto-policies(7). To see
604 the defaults and how to modify this default, see manual page
605 update-crypto-policies(8).
606 Specifies the available KEX (Key Exchange) algorithms. Multiple
608 algorithms must be comma-separated. Alternately if the specified
609 list begins with a ‘+’ character, then the specified methods will
610 be appended to the built-in openssh default set instead of re‐
611 placing them. If the specified list begins with a ‘-’ character,
612 then the specified methods (including wildcards) will be removed
613 from the built-in openssh default set instead of replacing them.
614 If the specified list begins with a ‘^’ character, then the spec‐
615 ified methods will be placed at the head of the built-in openssh
616 default set. The supported algorithms are:
617 curve25519-sha256
619 curve25519-sha256@libssh.org
620 diffie-hellman-group1-sha1
621 diffie-hellman-group14-sha1
622 diffie-hellman-group14-sha256
623 diffie-hellman-group16-sha512
624 diffie-hellman-group18-sha512
625 diffie-hellman-group-exchange-sha1
626 diffie-hellman-group-exchange-sha256
627 ecdh-sha2-nistp256
628 ecdh-sha2-nistp384
629 ecdh-sha2-nistp521
630 sntrup761x25519-sha512@openssh.com
631 The list of available key exchange algorithms may also be ob‐
633 tained using "ssh -Q KexAlgorithms".
634 ListenAddress
636 Specifies the local addresses sshd(8) should listen on. The fol‐
637 lowing forms may be used:
638 ListenAddress hostname|address [rdomain domain]
640 ListenAddress hostname:port [rdomain domain]
641 ListenAddress IPv4_address:port [rdomain domain]
642 ListenAddress [hostname|address]:port [rdomain domain]
643 The optional rdomain qualifier requests sshd(8) listen in an ex‐
645 plicit routing domain. If port is not specified, sshd will lis‐
646 ten on the address and all Port options specified. The default
647 is to listen on all local addresses on the current default rout‐
648 ing domain. Multiple ListenAddress options are permitted. For
649 more information on routing domains, see rdomain(4).
650 LoginGraceTime
652 The server disconnects after this time if the user has not suc‐
653 cessfully logged in. If the value is 0, there is no time limit.
654 The default is 120 seconds.
655 LogLevel
657 Gives the verbosity level that is used when logging messages from
658 sshd(8). The possible values are: QUIET, FATAL, ERROR, INFO,
659 VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO.
660 DEBUG and DEBUG1 are equivalent. DEBUG2 and DEBUG3 each specify
661 higher levels of debugging output. Logging with a DEBUG level
662 violates the privacy of users and is not recommended.
663 LogVerbose
665 Specify one or more overrides to LogLevel. An override consists
666 of a pattern lists that matches the source file, function and
667 line number to force detailed logging for. For example, an over‐
668 ride pattern of:
669 kex.c:*:1000,*:kex_exchange_identification():*,packet.c:*
671 would enable detailed logging for line 1000 of kex.c, everything
673 in the kex_exchange_identification() function, and all code in
674 the packet.c file. This option is intended for debugging and no
675 overrides are enabled by default.
676 MACs The default is handled system-wide by crypto-policies(7). To see
678 the defaults and how to modify this default, see manual page
679 update-crypto-policies(8).
680 Specifies the available MAC (message authentication code) algo‐
682 rithms. The MAC algorithm is used for data integrity protection.
683 Multiple algorithms must be comma-separated. If the specified
684 list begins with a ‘+’ character, then the specified algorithms
685 will be appended to the built-in openssh default set instead of
686 replacing them. If the specified list begins with a ‘-’ charac‐
687 ter, then the specified algorithms (including wildcards) will be
688 removed from the built-in openssh default set instead of replac‐
689 ing them. If the specified list begins with a ‘^’ character,
690 then the specified algorithms will be placed at the head of the
691 built-in openssh default set.
692 The algorithms that contain "-etm" calculate the MAC after en‐
694 cryption (encrypt-then-mac). These are considered safer and
695 their use recommended. The supported MACs are:
696 hmac-md5
698 hmac-md5-96
699 hmac-sha1
700 hmac-sha1-96
701 hmac-sha2-256
702 hmac-sha2-512
703 umac-64@openssh.com
704 umac-128@openssh.com
705 hmac-md5-etm@openssh.com
706 hmac-md5-96-etm@openssh.com
707 hmac-sha1-etm@openssh.com
708 hmac-sha1-96-etm@openssh.com
709 hmac-sha2-256-etm@openssh.com
710 hmac-sha2-512-etm@openssh.com
711 umac-64-etm@openssh.com
712 umac-128-etm@openssh.com
713 The list of available MAC algorithms may also be obtained using
715 "ssh -Q mac".
716 Match Introduces a conditional block. If all of the criteria on the
718 Match line are satisfied, the keywords on the following lines
719 override those set in the global section of the config file, un‐
720 til either another Match line or the end of the file. If a key‐
721 word appears in multiple Match blocks that are satisfied, only
722 the first instance of the keyword is applied.
723 The arguments to Match are one or more criteria-pattern pairs or
725 the single token All which matches all criteria. The available
726 criteria are User, Group, Host, LocalAddress, LocalPort, RDomain,
727 and Address (with RDomain representing the rdomain(4) on which
728 the connection was received).
729 The match patterns may consist of single entries or comma-sepa‐
731 rated lists and may use the wildcard and negation operators de‐
732 scribed in the PATTERNS section of ssh_config(5).
733 The patterns in an Address criteria may additionally contain ad‐
735 dresses to match in CIDR address/masklen format, such as
736 192.0.2.0/24 or 2001:db8::/32. Note that the mask length pro‐
737 vided must be consistent with the address - it is an error to
738 specify a mask length that is too long for the address or one
739 with bits set in this host portion of the address. For example,
740 192.0.2.0/33 and 192.0.2.0/8, respectively.
741 Only a subset of keywords may be used on the lines following a
743 Match keyword. Available keywords are AcceptEnv,
744 AllowAgentForwarding, AllowGroups, AllowStreamLocalForwarding,
745 AllowTcpForwarding, AllowUsers, AuthenticationMethods,
746 AuthorizedKeysCommand, AuthorizedKeysCommandUser,
747 AuthorizedKeysFile, AuthorizedPrincipalsCommand,
748 AuthorizedPrincipalsCommandUser, AuthorizedPrincipalsFile,
749 Banner, ChrootDirectory, ClientAliveCountMax,
750 ClientAliveInterval, DenyGroups, DenyUsers, DisableForwarding,
751 ForceCommand, GatewayPorts, GSSAPIAuthentication,
752 HostbasedAcceptedAlgorithms, HostbasedAuthentication,
753 HostbasedUsesNameFromPacketOnly, IgnoreRhosts, Include, IPQoS,
754 KbdInteractiveAuthentication, KerberosAuthentication,
755 KerberosUseKuserok, LogLevel, MaxAuthTries, MaxSessions,
756 PasswordAuthentication, PermitEmptyPasswords, PermitListen,
757 PermitOpen, PermitRootLogin, PermitTTY, PermitTunnel,
758 PermitUserRC, PubkeyAcceptedAlgorithms, PubkeyAuthentication,
759 RekeyLimit, RevokedKeys, RDomain, SetEnv, StreamLocalBindMask,
760 StreamLocalBindUnlink, TrustedUserCAKeys, X11DisplayOffset,
761 X11MaxDisplays, X11Forwarding and X11UseLocalhost.
762 MaxAuthTries
764 Specifies the maximum number of authentication attempts permitted
765 per connection. Once the number of failures reaches half this
766 value, additional failures are logged. The default is 6.
767 MaxSessions
769 Specifies the maximum number of open shell, login or subsystem
770 (e.g. sftp) sessions permitted per network connection. Multiple
771 sessions may be established by clients that support connection
772 multiplexing. Setting MaxSessions to 1 will effectively disable
773 session multiplexing, whereas setting it to 0 will prevent all
774 shell, login and subsystem sessions while still permitting for‐
775 warding. The default is 10.
776 MaxStartups
778 Specifies the maximum number of concurrent unauthenticated con‐
779 nections to the SSH daemon. Additional connections will be
780 dropped until authentication succeeds or the LoginGraceTime ex‐
781 pires for a connection. The default is 10:30:100.
782 Alternatively, random early drop can be enabled by specifying the
784 three colon separated values start:rate:full (e.g. "10:30:60").
785 sshd(8) will refuse connection attempts with a probability of
786 rate/100 (30%) if there are currently start (10) unauthenticated
787 connections. The probability increases linearly and all connec‐
788 tion attempts are refused if the number of unauthenticated con‐
789 nections reaches full (60).
790 ModuliFile
792 Specifies the moduli(5) file that contains the Diffie-Hellman
793 groups used for the “diffie-hellman-group-exchange-sha1” and
794 “diffie-hellman-group-exchange-sha256” key exchange methods. The
795 default is /etc/gsissh/moduli.
796 PasswordAuthentication
798 Specifies whether password authentication is allowed. The de‐
799 fault is yes.
800 PermitEmptyPasswords
802 When password authentication is allowed, it specifies whether the
803 server allows login to accounts with empty password strings. The
804 default is no.
805 PermitListen
807 Specifies the addresses/ports on which a remote TCP port forward‐
808 ing may listen. The listen specification must be one of the fol‐
809 lowing forms:
810 PermitListen port
812 PermitListen host:port
813 Multiple permissions may be specified by separating them with
815 whitespace. An argument of any can be used to remove all re‐
816 strictions and permit any listen requests. An argument of none
817 can be used to prohibit all listen requests. The host name may
818 contain wildcards as described in the PATTERNS section in
819 ssh_config(5). The wildcard ‘*’ can also be used in place of a
820 port number to allow all ports. By default all port forwarding
821 listen requests are permitted. Note that the GatewayPorts option
822 may further restrict which addresses may be listened on. Note
823 also that ssh(1) will request a listen host of “localhost” if no
824 listen host was specifically requested, and this name is treated
825 differently to explicit localhost addresses of “127.0.0.1” and
826 “::1”.
827 PermitOpen
829 Specifies the destinations to which TCP port forwarding is per‐
830 mitted. The forwarding specification must be one of the follow‐
831 ing forms:
832 PermitOpen host:port
834 PermitOpen IPv4_addr:port
835 PermitOpen [IPv6_addr]:port
836 Multiple forwards may be specified by separating them with white‐
838 space. An argument of any can be used to remove all restrictions
839 and permit any forwarding requests. An argument of none can be
840 used to prohibit all forwarding requests. The wildcard ‘*’ can
841 be used for host or port to allow all hosts or ports respec‐
842 tively. Otherwise, no pattern matching or address lookups are
843 performed on supplied names. By default all port forwarding re‐
844 quests are permitted.
845 PermitRootLogin
847 Specifies whether root can log in using ssh(1). The argument
848 must be yes, prohibit-password, forced-commands-only, or no. The
849 default is prohibit-password.
850 If this option is set to prohibit-password (or its deprecated
852 alias, without-password), password and keyboard-interactive au‐
853 thentication are disabled for root.
854 If this option is set to forced-commands-only, root login with
856 public key authentication will be allowed, but only if the
857 command option has been specified (which may be useful for taking
858 remote backups even if root login is normally not allowed). All
859 other authentication methods are disabled for root.
860 If this option is set to no, root is not allowed to log in.
862 PermitTTY
864 Specifies whether pty(4) allocation is permitted. The default is
865 yes.
866 PermitTunnel
868 Specifies whether tun(4) device forwarding is allowed. The argu‐
869 ment must be yes, point-to-point (layer 3), ethernet (layer 2),
870 or no. Specifying yes permits both point-to-point and ethernet.
871 The default is no.
872 Independent of this setting, the permissions of the selected
874 tun(4) device must allow access to the user.
875 PermitUserEnvironment
877 Specifies whether ~/.ssh/environment and environment= options in
878 ~/.ssh/authorized_keys are processed by sshd(8). Valid options
879 are yes, no or a pattern-list specifying which environment vari‐
880 able names to accept (for example "LANG,LC_*"). The default is
881 no. Enabling environment processing may enable users to bypass
882 access restrictions in some configurations using mechanisms such
883 as LD_PRELOAD.
884 PermitUserRC
886 Specifies whether any ~/.ssh/rc file is executed. The default is
887 yes.
888 PerSourceMaxStartups
890 Specifies the number of unauthenticated connections allowed from
891 a given source address, or “none” if there is no limit. This
892 limit is applied in addition to MaxStartups, whichever is lower.
893 The default is none.
894 PerSourceNetBlockSize
896 Specifies the number of bits of source address that are grouped
897 together for the purposes of applying PerSourceMaxStartups lim‐
898 its. Values for IPv4 and optionally IPv6 may be specified, sepa‐
899 rated by a colon. The default is 32:128, which means each ad‐
900 dress is considered individually.
901 PidFile
903 Specifies the file that contains the process ID of the SSH dae‐
904 mon, or none to not write one. The default is
905 /var/run/gsisshd.pid.
906 Port Specifies the port number that sshd(8) listens on. The default
908 is 22. Multiple options of this type are permitted. See also
909 ListenAddress.
910 PrintLastLog
912 Specifies whether sshd(8) should print the date and time of the
913 last user login when a user logs in interactively. The default
914 is yes.
915 PrintMotd
917 Specifies whether sshd(8) should print /etc/motd when a user logs
918 in interactively. (On some systems it is also printed by the
919 shell, /etc/profile, or equivalent.) The default is yes.
920 PubkeyAcceptedAlgorithms
922 The default is handled system-wide by crypto-policies(7). To see
923 the defaults and how to modify this default, see manual page
924 update-crypto-policies(8).
925 Specifies the signature algorithms that will be accepted for pub‐
927 lic key authentication as a list of comma-separated patterns.
928 Alternately if the specified list begins with a ‘+’ character,
929 then the specified algorithms will be appended to the built-in
930 openssh default set instead of replacing them. If the specified
931 list begins with a ‘-’ character, then the specified algorithms
932 (including wildcards) will be removed from the built-in openssh
933 default set instead of replacing them. If the specified list be‐
934 gins with a ‘^’ character, then the specified algorithms will be
935 placed at the head of the built-in openssh default set.
936 The list of available signature algorithms may also be obtained
938 using "ssh -Q PubkeyAcceptedAlgorithms".
939 PubkeyAuthOptions
941 Sets one or more public key authentication options. The sup‐
942 ported keywords are: none (the default; indicating no additional
943 options are enabled), touch-required and verify-required.
944 The touch-required option causes public key authentication using
946 a FIDO authenticator algorithm (i.e. ecdsa-sk or ed25519-sk) to
947 always require the signature to attest that a physically present
948 user explicitly confirmed the authentication (usually by touching
949 the authenticator). By default, sshd(8) requires user presence
950 unless overridden with an authorized_keys option. The
951 touch-required flag disables this override.
952 The verify-required option requires a FIDO key signature attest
954 that the user was verified, e.g. via a PIN.
955 Neither the touch-required or verify-required options have any
957 effect for other, non-FIDO, public key types.
958 PubkeyAuthentication
960 Specifies whether public key authentication is allowed. The de‐
961 fault is yes.
962 RekeyLimit
964 Specifies the maximum amount of data that may be transmitted be‐
965 fore the session key is renegotiated, optionally followed by a
966 maximum amount of time that may pass before the session key is
967 renegotiated. The first argument is specified in bytes and may
968 have a suffix of ‘K’, ‘M’, or ‘G’ to indicate Kilobytes,
969 Megabytes, or Gigabytes, respectively. The default is between
970 ‘1G’ and ‘4G’, depending on the cipher. The optional second
971 value is specified in seconds and may use any of the units docu‐
972 mented in the TIME FORMATS section. The default value for
973 RekeyLimit is default none, which means that rekeying is per‐
974 formed after the cipher's default amount of data has been sent or
975 received and no time based rekeying is done.
976 RevokedKeys
978 Specifies revoked public keys file, or none to not use one. Keys
979 listed in this file will be refused for public key authentica‐
980 tion. Note that if this file is not readable, then public key
981 authentication will be refused for all users. Keys may be speci‐
982 fied as a text file, listing one public key per line, or as an
983 OpenSSH Key Revocation List (KRL) as generated by ssh-keygen(1).
984 For more information on KRLs, see the KEY REVOCATION LISTS sec‐
985 tion in ssh-keygen(1).
986 RDomain
988 Specifies an explicit routing domain that is applied after au‐
989 thentication has completed. The user session, as well and any
990 forwarded or listening IP sockets, will be bound to this
991 rdomain(4). If the routing domain is set to %D, then the domain
992 in which the incoming connection was received will be applied.
993 SecurityKeyProvider
995 Specifies a path to a library that will be used when loading FIDO
996 authenticator-hosted keys, overriding the default of using the
997 built-in USB HID support.
998 SetEnv Specifies one or more environment variables to set in child ses‐
1000 sions started by sshd(8) as “NAME=VALUE”. The environment value
1001 may be quoted (e.g. if it contains whitespace characters). Envi‐
1002 ronment variables set by SetEnv override the default environment
1003 and any variables specified by the user via AcceptEnv or
1004 PermitUserEnvironment.
1005 StreamLocalBindMask
1007 Sets the octal file creation mode mask (umask) used when creating
1008 a Unix-domain socket file for local or remote port forwarding.
1009 This option is only used for port forwarding to a Unix-domain
1010 socket file.
1011 The default value is 0177, which creates a Unix-domain socket
1013 file that is readable and writable only by the owner. Note that
1014 not all operating systems honor the file mode on Unix-domain
1015 socket files.
1016 StreamLocalBindUnlink
1018 Specifies whether to remove an existing Unix-domain socket file
1019 for local or remote port forwarding before creating a new one.
1020 If the socket file already exists and StreamLocalBindUnlink is
1021 not enabled, sshd will be unable to forward the port to the Unix-
1022 domain socket file. This option is only used for port forwarding
1023 to a Unix-domain socket file.
1024 The argument must be yes or no. The default is no.
1026 StrictModes
1028 Specifies whether sshd(8) should check file modes and ownership
1029 of the user's files and home directory before accepting login.
1030 This is normally desirable because novices sometimes accidentally
1031 leave their directory or files world-writable. The default is
1032 yes. Note that this does not apply to ChrootDirectory, whose
1033 permissions and ownership are checked unconditionally.
1034 Subsystem
1036 Configures an external subsystem (e.g. file transfer daemon).
1037 Arguments should be a subsystem name and a command (with optional
1038 arguments) to execute upon subsystem request.
1039 The command sftp-server implements the SFTP file transfer subsys‐
1041 tem.
1042 Alternately the name internal-sftp implements an in-process SFTP
1044 server. This may simplify configurations using ChrootDirectory
1045 to force a different filesystem root on clients.
1046 By default no subsystems are defined.
1048 SyslogFacility
1050 Gives the facility code that is used when logging messages from
1051 sshd(8). The possible values are: DAEMON, USER, AUTH, AUTHPRIV,
1052 LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7.
1053 The default is AUTH.
1054 TCPKeepAlive
1056 Specifies whether the system should send TCP keepalive messages
1057 to the other side. If they are sent, death of the connection or
1058 crash of one of the machines will be properly noticed. However,
1059 this means that connections will die if the route is down tempo‐
1060 rarily, and some people find it annoying. On the other hand, if
1061 TCP keepalives are not sent, sessions may hang indefinitely on
1062 the server, leaving "ghost" users and consuming server resources.
1063 The default is yes (to send TCP keepalive messages), and the
1065 server will notice if the network goes down or the client host
1066 crashes. This avoids infinitely hanging sessions.
1067 To disable TCP keepalive messages, the value should be set to no.
1069 TrustedUserCAKeys
1071 Specifies a file containing public keys of certificate authori‐
1072 ties that are trusted to sign user certificates for authentica‐
1073 tion, or none to not use one. Keys are listed one per line;
1074 empty lines and comments starting with ‘#’ are allowed. If a
1075 certificate is presented for authentication and has its signing
1076 CA key listed in this file, then it may be used for authentica‐
1077 tion for any user listed in the certificate's principals list.
1078 Note that certificates that lack a list of principals will not be
1079 permitted for authentication using TrustedUserCAKeys. For more
1080 details on certificates, see the CERTIFICATES section in
1081 ssh-keygen(1).
1082 UseDNS Specifies whether sshd(8) should look up the remote host name,
1084 and to check that the resolved host name for the remote IP ad‐
1085 dress maps back to the very same IP address.
1086 If this option is set to no (the default) then only addresses and
1088 not host names may be used in ~/.ssh/authorized_keys from and
1089 sshd_config Match Host directives.
1090 UsePAM Enables the Pluggable Authentication Module interface. If set to
1092 yes this will enable PAM authentication using
1093 ChallengeResponseAuthentication and PasswordAuthentication in ad‐
1094 dition to PAM account and session module processing for all au‐
1095 thentication types.
1096 Because PAM challenge-response authentication usually serves an
1098 equivalent role to password authentication, you should disable
1099 either PasswordAuthentication or ChallengeResponseAuthentication.
1100 If UsePAM is enabled, you will not be able to run sshd(8) as a
1102 non-root user. The default is no.
1103 PermitPAMUserChange
1105 If set to yes this will enable PAM authentication to change the
1106 name of the user being authenticated. The default is no.
1107 VersionAddendum
1109 Optionally specifies additional text to append to the SSH proto‐
1110 col banner sent by the server upon connection. The default is
1111 none.
1112 X11DisplayOffset
1114 Specifies the first display number available for sshd(8)'s X11
1115 forwarding. This prevents sshd from interfering with real X11
1116 servers. The default is 10.
1117 X11MaxDisplays
1119 Specifies the maximum number of displays available for sshd(8)'s
1120 X11 forwarding. This prevents sshd from exhausting local ports.
1121 The default is 1000.
1122 X11Forwarding
1124 Specifies whether X11 forwarding is permitted. The argument must
1125 be yes or no. The default is no.
1126 When X11 forwarding is enabled, there may be additional exposure
1128 to the server and to client displays if the sshd(8) proxy display
1129 is configured to listen on the wildcard address (see
1130 X11UseLocalhost), though this is not the default. Additionally,
1131 the authentication spoofing and authentication data verification
1132 and substitution occur on the client side. The security risk of
1133 using X11 forwarding is that the client's X11 display server may
1134 be exposed to attack when the SSH client requests forwarding (see
1135 the warnings for ForwardX11 in ssh_config(5)). A system adminis‐
1136 trator may have a stance in which they want to protect clients
1137 that may expose themselves to attack by unwittingly requesting
1138 X11 forwarding, which can warrant a no setting.
1139 Note that disabling X11 forwarding does not prevent users from
1141 forwarding X11 traffic, as users can always install their own
1142 forwarders.
1143 X11UseLocalhost
1145 Specifies whether sshd(8) should bind the X11 forwarding server
1146 to the loopback address or to the wildcard address. By default,
1147 sshd binds the forwarding server to the loopback address and sets
1148 the hostname part of the DISPLAY environment variable to
1149 localhost. This prevents remote hosts from connecting to the
1150 proxy display. However, some older X11 clients may not function
1151 with this configuration. X11UseLocalhost may be set to no to
1152 specify that the forwarding server should be bound to the wild‐
1153 card address. The argument must be yes or no. The default is
1154 yes.
1155 XAuthLocation
1157 Specifies the full pathname of the xauth(1) program, or none to
1158 not use one. The default is /usr/bin/xauth.
1159
1161 sshd(8) command-line arguments and configuration file options that spec‐
1162 ify time may be expressed using a sequence of the form: time[qualifier],
1163 where time is a positive integer value and qualifier is one of the fol‐
1164 lowing:
1165 ⟨none⟩ seconds
1167 s | S seconds
1168 m | M minutes
1169 h | H hours
1170 d | D days
1171 w | W weeks
1172 Each member of the sequence is added together to calculate the total time
1174 value.
1175 Time format examples:
1177 600 600 seconds (10 minutes)
1179 10m 10 minutes
1180 1h30m 1 hour 30 minutes (90 minutes)
1181
1183 Arguments to some keywords can make use of tokens, which are expanded at
1184 runtime:
1185 %% A literal ‘%’.
1187 %D The routing domain in which the incoming connection was re‐
1188 ceived.
1189 %F The fingerprint of the CA key.
1190 %f The fingerprint of the key or certificate.
1191 %h The home directory of the user.
1192 %i The key ID in the certificate.
1193 %K The base64-encoded CA key.
1194 %k The base64-encoded key or certificate for authentication.
1195 %s The serial number of the certificate.
1196 %T The type of the CA key.
1197 %t The key or certificate type.
1198 %U The numeric user ID of the target user.
1199 %u The username.
1200 AuthorizedKeysCommand accepts the tokens %%, %f, %h, %k, %t, %U, and %u.
1202 AuthorizedKeysFile accepts the tokens %%, %h, %U, and %u.
1204 AuthorizedPrincipalsCommand accepts the tokens %%, %F, %f, %h, %i, %K,
1206 %k, %s, %T, %t, %U, and %u.
1207 AuthorizedPrincipalsFile accepts the tokens %%, %h, %U, and %u.
1209 ChrootDirectory accepts the tokens %%, %h, %U, and %u.
1211 RoutingDomain accepts the token %D.
1213
1215 /etc/gsissh/sshd_config
1216 Contains configuration data for sshd(8). This file should be
1217 writable by root only, but it is recommended (though not neces‐
1218 sary) that it be world-readable.
1219
1221 sftp-server(8), sshd(8)
1222
1224 OpenSSH is a derivative of the original and free ssh 1.2.12 release by
1225 Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo
1226 de Raadt and Dug Song removed many bugs, re-added newer features and cre‐
1227 ated OpenSSH. Markus Friedl contributed the support for SSH protocol
1228 versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support
1229 for privilege separation.
1230BSD April 4, 2021 BSD