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Diffstat (limited to 'crypto/openssh/sshd_config.0')
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diff --git a/crypto/openssh/sshd_config.0 b/crypto/openssh/sshd_config.0 deleted file mode 100644 index 1cc7459..0000000 --- a/crypto/openssh/sshd_config.0 +++ /dev/null @@ -1,1052 +0,0 @@ -SSHD_CONFIG(5) File Formats Manual SSHD_CONFIG(5) - -NAME - sshd_config M-bM-^@M-^S OpenSSH SSH daemon configuration file - -SYNOPSIS - /etc/ssh/sshd_config - -DESCRIPTION - sshd(8) reads configuration data from /etc/ssh/sshd_config (or the file - specified with -f on the command line). The file contains keyword- - argument pairs, one per line. Lines starting with M-bM-^@M-^X#M-bM-^@M-^Y and empty lines - are interpreted as comments. Arguments may optionally be enclosed in - double quotes (") in order to represent arguments containing spaces. - - The possible keywords and their meanings are as follows (note that - keywords are case-insensitive and arguments are case-sensitive): - - AcceptEnv - Specifies what environment variables sent by the client will be - copied into the session's environ(7). See SendEnv in - ssh_config(5) for how to configure the client. Note that - environment passing is only supported for protocol 2, and that - the TERM environment variable is always sent whenever the client - requests a pseudo-terminal as it is required by the protocol. - Variables are specified by name, which may contain the wildcard - characters M-bM-^@M-^X*M-bM-^@M-^Y and M-bM-^@M-^X?M-bM-^@M-^Y. Multiple environment variables may be - separated by whitespace or spread across multiple AcceptEnv - directives. Be warned that some environment variables could be - used to bypass restricted user environments. For this reason, - care should be taken in the use of this directive. The default - is not to accept any environment variables. - - AddressFamily - Specifies which address family should be used by sshd(8). Valid - 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 - only). The default is M-bM-^@M-^\anyM-bM-^@M-^]. - - AllowAgentForwarding - Specifies whether ssh-agent(1) forwarding is permitted. The - default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that disabling agent forwarding does not - improve security unless users are also denied shell access, as - they can always install their own forwarders. - - AllowGroups - This keyword can be followed by a list of group name patterns, - separated by spaces. If specified, login is allowed only for - users whose primary group or supplementary group list matches one - of the patterns. Only group names are valid; a numerical group - ID is not recognized. By default, login is allowed for all - groups. The allow/deny directives are processed in the following - order: DenyUsers, AllowUsers, DenyGroups, and finally - AllowGroups. - - See PATTERNS in ssh_config(5) for more information on patterns. - - AllowTcpForwarding - Specifies whether TCP forwarding is permitted. The available - 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 - prevent all TCP forwarding, M-bM-^@M-^\localM-bM-^@M-^] to allow local (from the - perspective of ssh(1)) forwarding only or M-bM-^@M-^\remoteM-bM-^@M-^] to allow - remote forwarding only. The default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that - disabling TCP forwarding does not improve security unless users - are also denied shell access, as they can always install their - own forwarders. - - AllowStreamLocalForwarding - Specifies whether StreamLocal (Unix-domain socket) forwarding is - permitted. The available options are M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\allM-bM-^@M-^] to allow - StreamLocal forwarding, M-bM-^@M-^\noM-bM-^@M-^] to prevent all StreamLocal - forwarding, M-bM-^@M-^\localM-bM-^@M-^] to allow local (from the perspective of - ssh(1)) forwarding only or M-bM-^@M-^\remoteM-bM-^@M-^] to allow remote forwarding - only. The default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that disabling StreamLocal - forwarding does not improve security unless users are also denied - shell access, as they can always install their own forwarders. - - AllowUsers - This keyword can be followed by a list of user name patterns, - separated by spaces. If specified, login is allowed only for - user names that match one of the patterns. Only user names are - valid; a numerical user ID is not recognized. By default, login - is allowed for all users. If the pattern takes the form - USER@HOST then USER and HOST are separately checked, restricting - logins to particular users from particular hosts. The allow/deny - directives are processed in the following order: DenyUsers, - AllowUsers, DenyGroups, and finally AllowGroups. - - See PATTERNS in ssh_config(5) for more information on patterns. - - AuthenticationMethods - Specifies the authentication methods that must be successfully - completed for a user to be granted access. This option must be - followed by one or more comma-separated lists of authentication - method names. Successful authentication requires completion of - every method in at least one of these lists. - - For example, an argument of M-bM-^@M-^\publickey,password - publickey,keyboard-interactiveM-bM-^@M-^] would require the user to - complete public key authentication, followed by either password - or keyboard interactive authentication. Only methods that are - next in one or more lists are offered at each stage, so for this - example, it would not be possible to attempt password or - keyboard-interactive authentication before public key. - - For keyboard interactive authentication it is also possible to - restrict authentication to a specific device by appending a colon - followed by the device identifier M-bM-^@M-^\bsdauthM-bM-^@M-^], M-bM-^@M-^\pamM-bM-^@M-^], or M-bM-^@M-^\skeyM-bM-^@M-^], - depending on the server configuration. For example, - M-bM-^@M-^\keyboard-interactive:bsdauthM-bM-^@M-^] would restrict keyboard - interactive authentication to the M-bM-^@M-^\bsdauthM-bM-^@M-^] device. - - If the M-bM-^@M-^\publickeyM-bM-^@M-^] method is listed more than once, sshd(8) - verifies that keys that have been used successfully are not - reused for subsequent authentications. For example, an - AuthenticationMethods of M-bM-^@M-^\publickey,publickeyM-bM-^@M-^] will require - successful authentication using two different public keys. - - This option is only available for SSH protocol 2 and will yield a - fatal error if enabled if protocol 1 is also enabled. Note that - each authentication method listed should also be explicitly - enabled in the configuration. The default is not to require - multiple authentication; successful completion of a single - authentication method is sufficient. - - AuthorizedKeysCommand - Specifies a program to be used to look up the user's public keys. - The program must be owned by root, not writable by group or - others and specified by an absolute path. - - Arguments to AuthorizedKeysCommand may be provided using the - following tokens, which will be expanded at runtime: %% is - replaced by a literal '%', %u is replaced by the username being - authenticated, %h is replaced by the home directory of the user - being authenticated, %t is replaced with the key type offered for - authentication, %f is replaced with the fingerprint of the key, - and %k is replaced with the key being offered for authentication. - If no arguments are specified then the username of the target - user will be supplied. - - The program should produce on standard output zero or more lines - of authorized_keys output (see AUTHORIZED_KEYS in sshd(8)). If a - key supplied by AuthorizedKeysCommand does not successfully - authenticate and authorize the user then public key - authentication continues using the usual AuthorizedKeysFile - files. By default, no AuthorizedKeysCommand is run. - - AuthorizedKeysCommandUser - Specifies the user under whose account the AuthorizedKeysCommand - is run. It is recommended to use a dedicated user that has no - other role on the host than running authorized keys commands. If - AuthorizedKeysCommand is specified but AuthorizedKeysCommandUser - is not, then sshd(8) will refuse to start. - - AuthorizedKeysFile - Specifies the file that contains the public keys that can be used - for user authentication. The format is described in the - AUTHORIZED_KEYS FILE FORMAT section of sshd(8). - AuthorizedKeysFile may contain tokens of the form %T which are - substituted during connection setup. The following tokens are - defined: %% is replaced by a literal '%', %h is replaced by the - home directory of the user being authenticated, and %u is - replaced by the username of that user. After expansion, - AuthorizedKeysFile is taken to be an absolute path or one - relative to the user's home directory. Multiple files may be - listed, separated by whitespace. The default is - M-bM-^@M-^\.ssh/authorized_keys .ssh/authorized_keys2M-bM-^@M-^]. - - AuthorizedPrincipalsCommand - Specifies a program to be used to generate the list of allowed - certificate principals as per AuthorizedPrincipalsFile. The - program must be owned by root, not writable by group or others - and specified by an absolute path. - - Arguments to AuthorizedPrincipalsCommand may be provided using - the following tokens, which will be expanded at runtime: %% is - replaced by a literal '%', %u is replaced by the username being - authenticated and %h is replaced by the home directory of the - user being authenticated. - - The program should produce on standard output zero or more lines - of AuthorizedPrincipalsFile output. If either - AuthorizedPrincipalsCommand or AuthorizedPrincipalsFile is - specified, then certificates offered by the client for - authentication must contain a principal that is listed. By - default, no AuthorizedPrincipalsCommand is run. - - AuthorizedPrincipalsCommandUser - Specifies the user under whose account the - AuthorizedPrincipalsCommand is run. It is recommended to use a - dedicated user that has no other role on the host than running - authorized principals commands. If AuthorizedPrincipalsCommand - is specified but AuthorizedPrincipalsCommandUser is not, then - sshd(8) will refuse to start. - - AuthorizedPrincipalsFile - Specifies a file that lists principal names that are accepted for - certificate authentication. When using certificates signed by a - key listed in TrustedUserCAKeys, this file lists names, one of - which must appear in the certificate for it to be accepted for - authentication. Names are listed one per line preceded by key - options (as described in AUTHORIZED_KEYS FILE FORMAT in sshd(8)). - Empty lines and comments starting with M-bM-^@M-^X#M-bM-^@M-^Y are ignored. - - AuthorizedPrincipalsFile may contain tokens of the form %T which - are substituted during connection setup. The following tokens - are defined: %% is replaced by a literal '%', %h is replaced by - the home directory of the user being authenticated, and %u is - replaced by the username of that user. After expansion, - AuthorizedPrincipalsFile is taken to be an absolute path or one - relative to the user's home directory. - - The default is M-bM-^@M-^\noneM-bM-^@M-^], i.e. not to use a principals file M-bM-^@M-^S in - this case, the username of the user must appear in a - certificate's principals list for it to be accepted. Note that - AuthorizedPrincipalsFile is only used when authentication - proceeds using a CA listed in TrustedUserCAKeys and is not - consulted for certification authorities trusted via - ~/.ssh/authorized_keys, though the principals= key option offers - a similar facility (see sshd(8) for details). - - Banner The contents of the specified file are sent to the remote user - before authentication is allowed. If the argument is M-bM-^@M-^\noneM-bM-^@M-^] then - no banner is displayed. This option is only available for - protocol version 2. By default, no banner is displayed. - - ChallengeResponseAuthentication - Specifies whether challenge-response authentication is allowed - (e.g. via PAM or through authentication styles supported in - login.conf(5)) The default is M-bM-^@M-^\yesM-bM-^@M-^]. - - ChrootDirectory - Specifies the pathname of a directory to chroot(2) to after - authentication. At session startup sshd(8) checks that all - components of the pathname are root-owned directories which are - not writable by any other user or group. After the chroot, - sshd(8) changes the working directory to the user's home - directory. - - The pathname may contain the following tokens that are expanded - at runtime once the connecting user has been authenticated: %% is - replaced by a literal '%', %h is replaced by the home directory - of the user being authenticated, and %u is replaced by the - username of that user. - - The ChrootDirectory must contain the necessary files and - directories to support the user's session. For an interactive - session this requires at least a shell, typically sh(1), and - basic /dev nodes such as null(4), zero(4), stdin(4), stdout(4), - stderr(4), and tty(4) devices. For file transfer sessions using - M-bM-^@M-^\sftpM-bM-^@M-^], no additional configuration of the environment is - necessary if the in-process sftp server is used, though sessions - which use logging may require /dev/log inside the chroot - directory on some operating systems (see sftp-server(8) for - details). - - For safety, it is very important that the directory hierarchy be - prevented from modification by other processes on the system - (especially those outside the jail). Misconfiguration can lead - to unsafe environments which sshd(8) cannot detect. - - The default is not to chroot(2). - - Ciphers - Specifies the ciphers allowed for protocol version 2. Multiple - ciphers must be comma-separated. If the specified value begins - with a M-bM-^@M-^X+M-bM-^@M-^Y character, then the specified ciphers will be appended - to the default set instead of replacing them. - - The supported ciphers are: - - 3des-cbc - aes128-cbc - aes192-cbc - aes256-cbc - aes128-ctr - aes192-ctr - aes256-ctr - aes128-gcm@openssh.com - aes256-gcm@openssh.com - arcfour - arcfour128 - arcfour256 - blowfish-cbc - cast128-cbc - chacha20-poly1305@openssh.com - - The default is: - - aes128-ctr,aes192-ctr,aes256-ctr, - aes128-gcm@openssh.com,aes256-gcm@openssh.com, - chacha20-poly1305@openssh.com - - The list of available ciphers may also be obtained using the -Q - option of ssh(1) with an argument of M-bM-^@M-^\cipherM-bM-^@M-^]. - - ClientAliveCountMax - Sets the number of client alive messages (see below) which may be - sent without sshd(8) receiving any messages back from the client. - If this threshold is reached while client alive messages are - being sent, sshd will disconnect the client, terminating the - session. It is important to note that the use of client alive - messages is very different from TCPKeepAlive (below). The client - alive messages are sent through the encrypted channel and - therefore will not be spoofable. The TCP keepalive option - enabled by TCPKeepAlive is spoofable. The client alive mechanism - is valuable when the client or server depend on knowing when a - connection has become inactive. - - The default value is 3. If ClientAliveInterval (see below) is - set to 15, and ClientAliveCountMax is left at the default, - unresponsive SSH clients will be disconnected after approximately - 45 seconds. This option applies to protocol version 2 only. - - ClientAliveInterval - Sets a timeout interval in seconds after which if no data has - been received from the client, sshd(8) will send a message - through the encrypted channel to request a response from the - client. The default is 0, indicating that these messages will - not be sent to the client. This option applies to protocol - version 2 only. - - Compression - Specifies whether compression is allowed, or delayed until the - user has authenticated successfully. The argument must be M-bM-^@M-^\yesM-bM-^@M-^], - M-bM-^@M-^\delayedM-bM-^@M-^], or M-bM-^@M-^\noM-bM-^@M-^]. The default is M-bM-^@M-^\delayedM-bM-^@M-^]. - - DenyGroups - This keyword can be followed by a list of group name patterns, - separated by spaces. Login is disallowed for users whose primary - group or supplementary group list matches one of the patterns. - Only group names are valid; a numerical group ID is not - recognized. By default, login is allowed for all groups. The - allow/deny directives are processed in the following order: - DenyUsers, AllowUsers, DenyGroups, and finally AllowGroups. - - See PATTERNS in ssh_config(5) for more information on patterns. - - DenyUsers - This keyword can be followed by a list of user name patterns, - separated by spaces. Login is disallowed for user names that - match one of the patterns. Only user names are valid; a - numerical user ID is not recognized. By default, login is - allowed for all users. If the pattern takes the form USER@HOST - then USER and HOST are separately checked, restricting logins to - particular users from particular hosts. The allow/deny - directives are processed in the following order: DenyUsers, - AllowUsers, DenyGroups, and finally AllowGroups. - - See PATTERNS in ssh_config(5) for more information on patterns. - - FingerprintHash - Specifies the hash algorithm used when logging key fingerprints. - 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-^]. - - ForceCommand - Forces the execution of the command specified by ForceCommand, - ignoring any command supplied by the client and ~/.ssh/rc if - present. The command is invoked by using the user's login shell - with the -c option. This applies to shell, command, or subsystem - execution. It is most useful inside a Match block. The command - originally supplied by the client is available in the - SSH_ORIGINAL_COMMAND environment variable. Specifying a command - of M-bM-^@M-^\internal-sftpM-bM-^@M-^] will force the use of an in-process sftp - server that requires no support files when used with - ChrootDirectory. - - GatewayPorts - Specifies whether remote hosts are allowed to connect to ports - forwarded for the client. By default, sshd(8) binds remote port - forwardings to the loopback address. This prevents other remote - hosts from connecting to forwarded ports. GatewayPorts can be - used to specify that sshd should allow remote port forwardings to - bind to non-loopback addresses, thus allowing other hosts to - connect. The argument may be M-bM-^@M-^\noM-bM-^@M-^] to force remote port - forwardings to be available to the local host only, M-bM-^@M-^\yesM-bM-^@M-^] to - force remote port forwardings to bind to the wildcard address, or - M-bM-^@M-^\clientspecifiedM-bM-^@M-^] to allow the client to select the address to - which the forwarding is bound. The default is M-bM-^@M-^\noM-bM-^@M-^]. - - GSSAPIAuthentication - Specifies whether user authentication based on GSSAPI is allowed. - The default is M-bM-^@M-^\noM-bM-^@M-^]. Note that this option applies to protocol - version 2 only. - - GSSAPICleanupCredentials - Specifies whether to automatically destroy the user's credentials - cache on logout. The default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that this option - applies to protocol version 2 only. - - GSSAPIStrictAcceptorCheck - Determines whether to be strict about the identity of the GSSAPI - acceptor a client authenticates against. If set to M-bM-^@M-^\yesM-bM-^@M-^] then - the client must authenticate against the host service on the - current hostname. If set to M-bM-^@M-^\noM-bM-^@M-^] then the client may - authenticate against any service key stored in the machine's - default store. This facility is provided to assist with - operation on multi homed machines. The default is M-bM-^@M-^\yesM-bM-^@M-^]. - - HostbasedAcceptedKeyTypes - Specifies the key types that will be accepted for hostbased - authentication as a comma-separated pattern list. Alternately if - the specified value begins with a M-bM-^@M-^X+M-bM-^@M-^Y character, then the - specified key types will be appended to the default set instead - of replacing them. The default for this option is: - - ecdsa-sha2-nistp256-cert-v01@openssh.com, - ecdsa-sha2-nistp384-cert-v01@openssh.com, - ecdsa-sha2-nistp521-cert-v01@openssh.com, - ssh-ed25519-cert-v01@openssh.com, - ssh-rsa-cert-v01@openssh.com, - ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, - ssh-ed25519,ssh-rsa - - The -Q option of ssh(1) may be used to list supported key types. - - HostbasedAuthentication - Specifies whether rhosts or /etc/hosts.equiv authentication - together with successful public key client host authentication is - allowed (host-based authentication). This option is similar to - RhostsRSAAuthentication and applies to protocol version 2 only. - The default is M-bM-^@M-^\noM-bM-^@M-^]. - - HostbasedUsesNameFromPacketOnly - Specifies whether or not the server will attempt to perform a - reverse name lookup when matching the name in the ~/.shosts, - ~/.rhosts, and /etc/hosts.equiv files during - HostbasedAuthentication. A setting of M-bM-^@M-^\yesM-bM-^@M-^] means that sshd(8) - uses the name supplied by the client rather than attempting to - resolve the name from the TCP connection itself. The default is - M-bM-^@M-^\noM-bM-^@M-^]. - - HostCertificate - Specifies a file containing a public host certificate. The - certificate's public key must match a private host key already - specified by HostKey. The default behaviour of sshd(8) is not to - load any certificates. - - HostKey - Specifies a file containing a private host key used by SSH. The - default is /etc/ssh/ssh_host_key for protocol version 1, and - /etc/ssh/ssh_host_dsa_key, /etc/ssh/ssh_host_ecdsa_key, - /etc/ssh/ssh_host_ed25519_key and /etc/ssh/ssh_host_rsa_key for - protocol version 2. - - Note that sshd(8) will refuse to use a file if it is group/world- - accessible and that the HostKeyAlgorithms option restricts which - of the keys are actually used by sshd(8). - - It is possible to have multiple host key files. M-bM-^@M-^\rsa1M-bM-^@M-^] keys are - used for version 1 and M-bM-^@M-^\dsaM-bM-^@M-^], 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 protocol. It is also possible to - specify public host key files instead. In this case operations - on the private key will be delegated to an ssh-agent(1). - - HostKeyAgent - Identifies the UNIX-domain socket used to communicate with an - agent that has access to the private host keys. If - M-bM-^@M-^\SSH_AUTH_SOCKM-bM-^@M-^] is specified, the location of the socket will be - read from the SSH_AUTH_SOCK environment variable. - - HostKeyAlgorithms - Specifies the protocol version 2 host key algorithms that the - server offers. The default for this option is: - - ecdsa-sha2-nistp256-cert-v01@openssh.com, - ecdsa-sha2-nistp384-cert-v01@openssh.com, - ecdsa-sha2-nistp521-cert-v01@openssh.com, - ssh-ed25519-cert-v01@openssh.com, - ssh-rsa-cert-v01@openssh.com, - ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, - ssh-ed25519,ssh-rsa - - The list of available key types may also be obtained using the -Q - option of ssh(1) with an argument of M-bM-^@M-^\keyM-bM-^@M-^]. - - IgnoreRhosts - Specifies that .rhosts and .shosts files will not be used in - RhostsRSAAuthentication or HostbasedAuthentication. - - /etc/hosts.equiv and /etc/shosts.equiv are still used. The - default is M-bM-^@M-^\yesM-bM-^@M-^]. - - IgnoreUserKnownHosts - Specifies whether sshd(8) should ignore the user's - ~/.ssh/known_hosts during RhostsRSAAuthentication or - HostbasedAuthentication. The default is M-bM-^@M-^\noM-bM-^@M-^]. - - IPQoS Specifies the IPv4 type-of-service or DSCP class for the - 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-^], - 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-^], - 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-^], - M-bM-^@M-^\lowdelayM-bM-^@M-^], M-bM-^@M-^\throughputM-bM-^@M-^], M-bM-^@M-^\reliabilityM-bM-^@M-^], or a numeric value. - This option may take one or two arguments, separated by - whitespace. If one argument is specified, it is used as the - packet class unconditionally. If two values are specified, the - first is automatically selected for interactive sessions and the - second for non-interactive sessions. The default is M-bM-^@M-^\lowdelayM-bM-^@M-^] - for interactive sessions and M-bM-^@M-^\throughputM-bM-^@M-^] for non-interactive - sessions. - - KbdInteractiveAuthentication - Specifies whether to allow keyboard-interactive authentication. - The argument to this keyword must be M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The default - is to use whatever value ChallengeResponseAuthentication is set - to (by default M-bM-^@M-^\yesM-bM-^@M-^]). - - KerberosAuthentication - Specifies whether the password provided by the user for - PasswordAuthentication will be validated through the Kerberos - KDC. To use this option, the server needs a Kerberos servtab - which allows the verification of the KDC's identity. The default - is M-bM-^@M-^\noM-bM-^@M-^]. - - KerberosGetAFSToken - If AFS is active and the user has a Kerberos 5 TGT, attempt to - acquire an AFS token before accessing the user's home directory. - The default is M-bM-^@M-^\noM-bM-^@M-^]. - - KerberosOrLocalPasswd - If password authentication through Kerberos fails then the - password will be validated via any additional local mechanism - such as /etc/passwd. The default is M-bM-^@M-^\yesM-bM-^@M-^]. - - KerberosTicketCleanup - Specifies whether to automatically destroy the user's ticket - cache file on logout. The default is M-bM-^@M-^\yesM-bM-^@M-^]. - - KexAlgorithms - Specifies the available KEX (Key Exchange) algorithms. Multiple - algorithms must be comma-separated. Alternately if the specified - value begins with a M-bM-^@M-^X+M-bM-^@M-^Y character, then the specified methods - will be appended to the default set instead of replacing them. - The supported algorithms are: - - curve25519-sha256@libssh.org - diffie-hellman-group1-sha1 - diffie-hellman-group14-sha1 - diffie-hellman-group-exchange-sha1 - diffie-hellman-group-exchange-sha256 - ecdh-sha2-nistp256 - ecdh-sha2-nistp384 - ecdh-sha2-nistp521 - - The default is: - - curve25519-sha256@libssh.org, - ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521, - diffie-hellman-group-exchange-sha256, - diffie-hellman-group14-sha1 - - The list of available key exchange algorithms may also be - obtained using the -Q option of ssh(1) with an argument of M-bM-^@M-^\kexM-bM-^@M-^]. - - KeyRegenerationInterval - In protocol version 1, the ephemeral server key is automatically - regenerated after this many seconds (if it has been used). The - purpose of regeneration is to prevent decrypting captured - sessions by later breaking into the machine and stealing the - keys. The key is never stored anywhere. If the value is 0, the - key is never regenerated. The default is 3600 (seconds). - - ListenAddress - Specifies the local addresses sshd(8) should listen on. The - following forms may be used: - - ListenAddress host|IPv4_addr|IPv6_addr - ListenAddress host|IPv4_addr:port - ListenAddress [host|IPv6_addr]:port - - If port is not specified, sshd will listen on the address and all - Port options specified. The default is to listen on all local - addresses. Multiple ListenAddress options are permitted. - - LoginGraceTime - The server disconnects after this time if the user has not - successfully logged in. If the value is 0, there is no time - limit. The default is 120 seconds. - - LogLevel - Gives the verbosity level that is used when logging messages from - sshd(8). The possible values are: QUIET, FATAL, ERROR, INFO, - VERBOSE, DEBUG, DEBUG1, DEBUG2, and DEBUG3. The default is INFO. - DEBUG and DEBUG1 are equivalent. DEBUG2 and DEBUG3 each specify - higher levels of debugging output. Logging with a DEBUG level - violates the privacy of users and is not recommended. - - MACs Specifies the available MAC (message authentication code) - algorithms. The MAC algorithm is used in protocol version 2 for - data integrity protection. Multiple algorithms must be comma- - separated. If the specified value begins with a M-bM-^@M-^X+M-bM-^@M-^Y character, - then the specified algorithms will be appended to the default set - instead of replacing them. - - The algorithms that contain M-bM-^@M-^\-etmM-bM-^@M-^] calculate the MAC after - encryption (encrypt-then-mac). These are considered safer and - their use recommended. The supported MACs are: - - hmac-md5 - hmac-md5-96 - hmac-ripemd160 - hmac-sha1 - hmac-sha1-96 - hmac-sha2-256 - hmac-sha2-512 - umac-64@openssh.com - umac-128@openssh.com - hmac-md5-etm@openssh.com - hmac-md5-96-etm@openssh.com - hmac-ripemd160-etm@openssh.com - hmac-sha1-etm@openssh.com - hmac-sha1-96-etm@openssh.com - hmac-sha2-256-etm@openssh.com - hmac-sha2-512-etm@openssh.com - umac-64-etm@openssh.com - umac-128-etm@openssh.com - - The default is: - - umac-64-etm@openssh.com,umac-128-etm@openssh.com, - hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com, - umac-64@openssh.com,umac-128@openssh.com, - hmac-sha2-256,hmac-sha2-512 - - The list of available MAC algorithms may also be obtained using - the -Q option of ssh(1) with an argument of M-bM-^@M-^\macM-bM-^@M-^]. - - Match Introduces a conditional block. If all of the criteria on the - Match line are satisfied, the keywords on the following lines - override those set in the global section of the config file, - until either another Match line or the end of the file. If a - keyword appears in multiple Match blocks that are satisfied, only - the first instance of the keyword is applied. - - The arguments to Match are one or more criteria-pattern pairs or - the single token All which matches all criteria. The available - criteria are User, Group, Host, LocalAddress, LocalPort, and - Address. The match patterns may consist of single entries or - comma-separated lists and may use the wildcard and negation - operators described in the PATTERNS section of ssh_config(5). - - The patterns in an Address criteria may additionally contain - addresses to match in CIDR address/masklen format, e.g. - M-bM-^@M-^\192.0.2.0/24M-bM-^@M-^] or M-bM-^@M-^\3ffe:ffff::/32M-bM-^@M-^]. Note that the mask length - provided must be consistent with the address - it is an error to - specify a mask length that is too long for the address or one - with bits set in this host portion of the address. For example, - M-bM-^@M-^\192.0.2.0/33M-bM-^@M-^] and M-bM-^@M-^\192.0.2.0/8M-bM-^@M-^] respectively. - - Only a subset of keywords may be used on the lines following a - Match keyword. Available keywords are AcceptEnv, - AllowAgentForwarding, AllowGroups, AllowStreamLocalForwarding, - AllowTcpForwarding, AllowUsers, AuthenticationMethods, - AuthorizedKeysCommand, AuthorizedKeysCommandUser, - AuthorizedKeysFile, AuthorizedPrincipalsFile, Banner, - ChrootDirectory, DenyGroups, DenyUsers, ForceCommand, - GatewayPorts, GSSAPIAuthentication, HostbasedAcceptedKeyTypes, - HostbasedAuthentication, HostbasedUsesNameFromPacketOnly, IPQoS, - KbdInteractiveAuthentication, KerberosAuthentication, - MaxAuthTries, MaxSessions, PasswordAuthentication, - PermitEmptyPasswords, PermitOpen, PermitRootLogin, PermitTTY, - PermitTunnel, PermitUserRC, PubkeyAcceptedKeyTypes, - PubkeyAuthentication, RekeyLimit, RevokedKeys, - RhostsRSAAuthentication, RSAAuthentication, StreamLocalBindMask, - StreamLocalBindUnlink, TrustedUserCAKeys, X11DisplayOffset, - X11Forwarding and X11UseLocalHost. - - MaxAuthTries - Specifies the maximum number of authentication attempts permitted - per connection. Once the number of failures reaches half this - value, additional failures are logged. The default is 6. - - MaxSessions - Specifies the maximum number of open sessions permitted per - network connection. The default is 10. - - MaxStartups - Specifies the maximum number of concurrent unauthenticated - connections to the SSH daemon. Additional connections will be - dropped until authentication succeeds or the LoginGraceTime - expires for a connection. The default is 10:30:100. - - Alternatively, random early drop can be enabled by specifying the - three colon separated values M-bM-^@M-^\start:rate:fullM-bM-^@M-^] (e.g. "10:30:60"). - sshd(8) will refuse connection attempts with a probability of - M-bM-^@M-^\rate/100M-bM-^@M-^] (30%) if there are currently M-bM-^@M-^\startM-bM-^@M-^] (10) - unauthenticated connections. The probability increases linearly - and all connection attempts are refused if the number of - unauthenticated connections reaches M-bM-^@M-^\fullM-bM-^@M-^] (60). - - PasswordAuthentication - Specifies whether password authentication is allowed. The - default is M-bM-^@M-^\yesM-bM-^@M-^]. - - PermitEmptyPasswords - When password authentication is allowed, it specifies whether the - server allows login to accounts with empty password strings. The - default is M-bM-^@M-^\noM-bM-^@M-^]. - - PermitOpen - Specifies the destinations to which TCP port forwarding is - permitted. The forwarding specification must be one of the - following forms: - - PermitOpen host:port - PermitOpen IPv4_addr:port - PermitOpen [IPv6_addr]:port - - Multiple forwards may be specified by separating them with - whitespace. An argument of M-bM-^@M-^\anyM-bM-^@M-^] can be used to remove all - restrictions and permit any forwarding requests. An argument of - M-bM-^@M-^\noneM-bM-^@M-^] can be used to prohibit all forwarding requests. By - default all port forwarding requests are permitted. - - PermitRootLogin - Specifies whether root can log in using ssh(1). The argument - must be M-bM-^@M-^\yesM-bM-^@M-^], M-bM-^@M-^\prohibit-passwordM-bM-^@M-^], M-bM-^@M-^\without-passwordM-bM-^@M-^], - M-bM-^@M-^\forced-commands-onlyM-bM-^@M-^], or M-bM-^@M-^\noM-bM-^@M-^]. The default is - M-bM-^@M-^\prohibit-passwordM-bM-^@M-^]. - - If this option is set to M-bM-^@M-^\prohibit-passwordM-bM-^@M-^] or - M-bM-^@M-^\without-passwordM-bM-^@M-^], password and keyboard-interactive - authentication are disabled for root. - - If this option is set to M-bM-^@M-^\forced-commands-onlyM-bM-^@M-^], root login with - public key authentication will be allowed, but only if the - command option has been specified (which may be useful for taking - remote backups even if root login is normally not allowed). All - other authentication methods are disabled for root. - - If this option is set to M-bM-^@M-^\noM-bM-^@M-^], root is not allowed to log in. - - PermitTunnel - Specifies whether tun(4) device forwarding is allowed. The - 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-^] - (layer 2), or M-bM-^@M-^\noM-bM-^@M-^]. Specifying M-bM-^@M-^\yesM-bM-^@M-^] permits both - M-bM-^@M-^\point-to-pointM-bM-^@M-^] and M-bM-^@M-^\ethernetM-bM-^@M-^]. The default is M-bM-^@M-^\noM-bM-^@M-^]. - - Independent of this setting, the permissions of the selected - tun(4) device must allow access to the user. - - PermitTTY - Specifies whether pty(4) allocation is permitted. The default is - M-bM-^@M-^\yesM-bM-^@M-^]. - - PermitUserEnvironment - Specifies whether ~/.ssh/environment and environment= options in - ~/.ssh/authorized_keys are processed by sshd(8). The default is - M-bM-^@M-^\noM-bM-^@M-^]. Enabling environment processing may enable users to bypass - access restrictions in some configurations using mechanisms such - as LD_PRELOAD. - - PermitUserRC - Specifies whether any ~/.ssh/rc file is executed. The default is - M-bM-^@M-^\yesM-bM-^@M-^]. - - PidFile - Specifies the file that contains the process ID of the SSH - daemon, or M-bM-^@M-^\noneM-bM-^@M-^] to not write one. The default is - /var/run/sshd.pid. - - Port Specifies the port number that sshd(8) listens on. The default - is 22. Multiple options of this type are permitted. See also - ListenAddress. - - PrintLastLog - Specifies whether sshd(8) should print the date and time of the - last user login when a user logs in interactively. The default - is M-bM-^@M-^\yesM-bM-^@M-^]. - - PrintMotd - Specifies whether sshd(8) should print /etc/motd when a user logs - in interactively. (On some systems it is also printed by the - shell, /etc/profile, or equivalent.) The default is M-bM-^@M-^\yesM-bM-^@M-^]. - - Protocol - Specifies the protocol versions sshd(8) supports. The possible - values are M-bM-^@M-^X1M-bM-^@M-^Y and M-bM-^@M-^X2M-bM-^@M-^Y. Multiple versions must be comma- - separated. The default is M-bM-^@M-^X2M-bM-^@M-^Y. Note that the order of the - protocol list does not indicate preference, because the client - selects among multiple protocol versions offered by the server. - Specifying M-bM-^@M-^\2,1M-bM-^@M-^] is identical to M-bM-^@M-^\1,2M-bM-^@M-^]. - - PubkeyAcceptedKeyTypes - Specifies the key types that will be accepted for public key - authentication as a comma-separated pattern list. Alternately if - the specified value begins with a M-bM-^@M-^X+M-bM-^@M-^Y character, then the - specified key types will be appended to the default set instead - of replacing them. The default for this option is: - - ecdsa-sha2-nistp256-cert-v01@openssh.com, - ecdsa-sha2-nistp384-cert-v01@openssh.com, - ecdsa-sha2-nistp521-cert-v01@openssh.com, - ssh-ed25519-cert-v01@openssh.com, - ssh-rsa-cert-v01@openssh.com, - ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521, - ssh-ed25519,ssh-rsa - - The -Q option of ssh(1) may be used to list supported key types. - - PubkeyAuthentication - Specifies whether public key authentication is allowed. The - default is M-bM-^@M-^\yesM-bM-^@M-^]. Note that this option applies to protocol - version 2 only. - - RekeyLimit - Specifies the maximum amount of data that may be transmitted - before the session key is renegotiated, optionally followed a - maximum amount of time that may pass before the session key is - renegotiated. The first argument is specified in bytes and may - 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, - Megabytes, or Gigabytes, respectively. The default is between - M-bM-^@M-^X1GM-bM-^@M-^Y and M-bM-^@M-^X4GM-bM-^@M-^Y, depending on the cipher. The optional second - value is specified in seconds and may use any of the units - documented in the TIME FORMATS section. The default value for - RekeyLimit is M-bM-^@M-^\default noneM-bM-^@M-^], which means that rekeying is - performed after the cipher's default amount of data has been sent - or received and no time based rekeying is done. This option - applies to protocol version 2 only. - - RevokedKeys - Specifies revoked public keys file, or M-bM-^@M-^\noneM-bM-^@M-^] to not use one. - Keys listed in this file will be refused for public key - authentication. Note that if this file is not readable, then - public key authentication will be refused for all users. Keys - may be specified as a text file, listing one public key per line, - or as an OpenSSH Key Revocation List (KRL) as generated by - ssh-keygen(1). For more information on KRLs, see the KEY - REVOCATION LISTS section in ssh-keygen(1). - - RhostsRSAAuthentication - Specifies whether rhosts or /etc/hosts.equiv authentication - together with successful RSA host authentication is allowed. The - default is M-bM-^@M-^\noM-bM-^@M-^]. This option applies to protocol version 1 only. - - RSAAuthentication - Specifies whether pure RSA authentication is allowed. The - default is M-bM-^@M-^\yesM-bM-^@M-^]. This option applies to protocol version 1 - only. - - ServerKeyBits - Defines the number of bits in the ephemeral protocol version 1 - server key. The default and minimum value is 1024. - - StreamLocalBindMask - Sets the octal file creation mode mask (umask) used when creating - a Unix-domain socket file for local or remote port forwarding. - This option is only used for port forwarding to a Unix-domain - socket file. - - The default value is 0177, which creates a Unix-domain socket - file that is readable and writable only by the owner. Note that - not all operating systems honor the file mode on Unix-domain - socket files. - - StreamLocalBindUnlink - Specifies whether to remove an existing Unix-domain socket file - for local or remote port forwarding before creating a new one. - If the socket file already exists and StreamLocalBindUnlink is - not enabled, sshd will be unable to forward the port to the Unix- - domain socket file. This option is only used for port forwarding - to a Unix-domain socket file. - - 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-^]. - - StrictModes - Specifies whether sshd(8) should check file modes and ownership - of the user's files and home directory before accepting login. - This is normally desirable because novices sometimes accidentally - leave their directory or files world-writable. The default is - M-bM-^@M-^\yesM-bM-^@M-^]. Note that this does not apply to ChrootDirectory, whose - permissions and ownership are checked unconditionally. - - Subsystem - Configures an external subsystem (e.g. file transfer daemon). - Arguments should be a subsystem name and a command (with optional - arguments) to execute upon subsystem request. - - The command sftp-server(8) implements the M-bM-^@M-^\sftpM-bM-^@M-^] file transfer - subsystem. - - Alternately the name M-bM-^@M-^\internal-sftpM-bM-^@M-^] implements an in-process - M-bM-^@M-^\sftpM-bM-^@M-^] server. This may simplify configurations using - ChrootDirectory to force a different filesystem root on clients. - - By default no subsystems are defined. Note that this option - applies to protocol version 2 only. - - SyslogFacility - Gives the facility code that is used when logging messages from - sshd(8). The possible values are: DAEMON, USER, AUTH, LOCAL0, - LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7. The - default is AUTH. - - TCPKeepAlive - Specifies whether the system should send TCP keepalive messages - to the other side. If they are sent, death of the connection or - crash of one of the machines will be properly noticed. However, - this means that connections will die if the route is down - temporarily, and some people find it annoying. On the other - hand, if TCP keepalives are not sent, sessions may hang - indefinitely on the server, leaving M-bM-^@M-^\ghostM-bM-^@M-^] users and consuming - server resources. - - The default is M-bM-^@M-^\yesM-bM-^@M-^] (to send TCP keepalive messages), and the - server will notice if the network goes down or the client host - crashes. This avoids infinitely hanging sessions. - - To disable TCP keepalive messages, the value should be set to - M-bM-^@M-^\noM-bM-^@M-^]. - - TrustedUserCAKeys - Specifies a file containing public keys of certificate - authorities that are trusted to sign user certificates for - authentication, or M-bM-^@M-^\noneM-bM-^@M-^] to not use one. Keys are listed one - per line; empty lines and comments starting with M-bM-^@M-^X#M-bM-^@M-^Y are allowed. - If a certificate is presented for authentication and has its - signing CA key listed in this file, then it may be used for - authentication for any user listed in the certificate's - principals list. Note that certificates that lack a list of - principals will not be permitted for authentication using - TrustedUserCAKeys. For more details on certificates, see the - CERTIFICATES section in ssh-keygen(1). - - UseDNS Specifies whether sshd(8) should look up the remote host name, - and to check that the resolved host name for the remote IP - address maps back to the very same IP address. - - If this option is set to M-bM-^@M-^\noM-bM-^@M-^] (the default) then only addresses - and not host names may be used in ~/.ssh/known_hosts from and - sshd_config(5) Match Host directives. - - UseLogin - Specifies whether login(1) is used for interactive login - sessions. The default is M-bM-^@M-^\noM-bM-^@M-^]. Note that login(1) is never used - for remote command execution. Note also, that if this is - enabled, X11Forwarding will be disabled because login(1) does not - know how to handle xauth(1) cookies. If UsePrivilegeSeparation - is specified, it will be disabled after authentication. - - UsePAM Enables the Pluggable Authentication Module interface. If set to - M-bM-^@M-^\yesM-bM-^@M-^] this will enable PAM authentication using - ChallengeResponseAuthentication and PasswordAuthentication in - addition to PAM account and session module processing for all - authentication types. - - Because PAM challenge-response authentication usually serves an - equivalent role to password authentication, you should disable - either PasswordAuthentication or ChallengeResponseAuthentication. - - If UsePAM is enabled, you will not be able to run sshd(8) as a - non-root user. The default is M-bM-^@M-^\noM-bM-^@M-^]. - - UsePrivilegeSeparation - Specifies whether sshd(8) separates privileges by creating an - unprivileged child process to deal with incoming network traffic. - After successful authentication, another process will be created - that has the privilege of the authenticated user. The goal of - privilege separation is to prevent privilege escalation by - containing any corruption within the unprivileged processes. The - default is M-bM-^@M-^\yesM-bM-^@M-^]. If UsePrivilegeSeparation is set to M-bM-^@M-^\sandboxM-bM-^@M-^] - then the pre-authentication unprivileged process is subject to - additional restrictions. - - VersionAddendum - Optionally specifies additional text to append to the SSH - protocol banner sent by the server upon connection. The default - is M-bM-^@M-^\noneM-bM-^@M-^]. - - X11DisplayOffset - Specifies the first display number available for sshd(8)'s X11 - forwarding. This prevents sshd from interfering with real X11 - servers. The default is 10. - - X11Forwarding - Specifies whether X11 forwarding is permitted. 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-^]. - - When X11 forwarding is enabled, there may be additional exposure - to the server and to client displays if the sshd(8) proxy display - is configured to listen on the wildcard address (see - X11UseLocalhost below), though this is not the default. - Additionally, the authentication spoofing and authentication data - verification and substitution occur on the client side. The - security risk of using X11 forwarding is that the client's X11 - display server may be exposed to attack when the SSH client - requests forwarding (see the warnings for ForwardX11 in - ssh_config(5)). A system administrator may have a stance in - which they want to protect clients that may expose themselves to - attack by unwittingly requesting X11 forwarding, which can - warrant a M-bM-^@M-^\noM-bM-^@M-^] setting. - - Note that disabling X11 forwarding does not prevent users from - forwarding X11 traffic, as users can always install their own - forwarders. X11 forwarding is automatically disabled if UseLogin - is enabled. - - X11UseLocalhost - Specifies whether sshd(8) should bind the X11 forwarding server - to the loopback address or to the wildcard address. By default, - sshd binds the forwarding server to the loopback address and sets - the hostname part of the DISPLAY environment variable to - M-bM-^@M-^\localhostM-bM-^@M-^]. This prevents remote hosts from connecting to the - proxy display. However, some older X11 clients may not function - with this configuration. X11UseLocalhost may be set to M-bM-^@M-^\noM-bM-^@M-^] to - specify that the forwarding server should be bound to the - wildcard address. The argument must be M-bM-^@M-^\yesM-bM-^@M-^] or M-bM-^@M-^\noM-bM-^@M-^]. The - default is M-bM-^@M-^\yesM-bM-^@M-^]. - - XAuthLocation - Specifies the full pathname of the xauth(1) program, or M-bM-^@M-^\noneM-bM-^@M-^] to - not use one. The default is /usr/X11R6/bin/xauth. - -TIME FORMATS - sshd(8) command-line arguments and configuration file options that - specify time may be expressed using a sequence of the form: - time[qualifier], where time is a positive integer value and qualifier is - one of the following: - - M-bM-^_M-(noneM-bM-^_M-) seconds - s | S seconds - m | M minutes - h | H hours - d | D days - w | W weeks - - Each member of the sequence is added together to calculate the total time - value. - - Time format examples: - - 600 600 seconds (10 minutes) - 10m 10 minutes - 1h30m 1 hour 30 minutes (90 minutes) - -FILES - /etc/ssh/sshd_config - Contains configuration data for sshd(8). This file should be - writable by root only, but it is recommended (though not - necessary) that it be world-readable. - -SEE ALSO - sshd(8) - -AUTHORS - OpenSSH is a derivative of the original and free ssh 1.2.12 release by - Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo - de Raadt and Dug Song removed many bugs, re-added newer features and - created OpenSSH. Markus Friedl contributed the support for SSH protocol - versions 1.5 and 2.0. Niels Provos and Markus Friedl contributed support - for privilege separation. - -OpenBSD 5.8 August 6, 2015 OpenBSD 5.8 |
