| SSHD_CONFIG(5) | File Formats Manual | SSHD_CONFIG(5) | 
sshd_config —
-f on the command line). The file contains
  keyword-argument pairs, one per line. Unless noted otherwise, for each
  keyword, the first obtained value will be used. Lines starting with
  ‘#’ 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):
AcceptEnvSendEnv and SetEnv in
      ssh_config(5) for how to
      configure the client. The TERM environment
      variable is always accepted 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
      ‘*’ and
      ‘?’. 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.AddressFamilyany (the default), inet
      (use IPv4 only), or inet6 (use IPv6 only).AllowAgentForwardingyes. Note that
      disabling agent forwarding does not improve security unless users are also
      denied shell access, as they can always install their own forwarders.AllowGroupsDenyGroups,
      AllowGroups.
    See PATTERNS in
        ssh_config(5) for more
        information on patterns. This keyword may appear multiple times in
        sshd_config with each instance appending to the
        list.
AllowStreamLocalForwardingyes (the
      default) or all to allow StreamLocal forwarding,
      no to prevent all StreamLocal forwarding,
      local to allow local (from the perspective of
      ssh(1)) forwarding only or
      remote to allow remote forwarding only. Note that
      disabling StreamLocal forwarding does not improve security unless users
      are also denied shell access, as they can always install their own
      forwarders.AllowTcpForwardingyes (the default) or all
      to allow TCP forwarding, no to prevent all TCP
      forwarding, local to allow local (from the
      perspective of ssh(1))
      forwarding only or remote to allow remote
      forwarding only. Note that disabling TCP forwarding does not improve
      security unless users are also denied shell access, as they can always
      install their own forwarders.AllowUsersDenyUsers,
      AllowUsers.
    See PATTERNS in
        ssh_config(5) for more
        information on patterns. This keyword may appear multiple times in
        sshd_config with each instance appending to the
        list.
AuthenticationMethodsany to indicate the default
      behaviour of accepting any single authentication method. If the default is
      overridden, then successful authentication requires completion of every
      method in at least one of these lists.
    For example, “publickey,password publickey,keyboard-interactive” 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 bsdauth,
        pam, or skey, depending
        on the server configuration. For example,
        “keyboard-interactive:bsdauth” would restrict keyboard
        interactive authentication to the bsdauth
        device.
If the publickey method is listed more than once, sshd(8) verifies that keys that have been used successfully are not reused for subsequent authentications. For example, “publickey,publickey” requires successful authentication using two different public keys.
Note that each authentication method listed should also be explicitly enabled in the configuration.
The available authentication methods are:
        “gssapi-with-mic”, “hostbased”,
        “keyboard-interactive”, “none” (used for
        access to password-less accounts when
        PermitEmptyPasswords is enabled),
        “password” and “publickey”.
AuthorizedKeysCommandAuthorizedKeysCommand accept the tokens described
      in the TOKENS section. If no arguments
      are specified then the username of the target user is used.
    The program should produce on standard output zero or more
        lines of authorized_keys output (see
        AUTHORIZED_KEYS in
        sshd(8)).
        AuthorizedKeysCommand is tried after the usual
        AuthorizedKeysFile files and will not be
        executed if a matching key is found there. By default, no
        AuthorizedKeysCommand is run.
AuthorizedKeysCommandUserAuthorizedKeysCommand 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.AuthorizedKeysFileAuthorizedKeysFile accept the tokens described
      in the TOKENS section. 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. Alternately this option may be set to
      none to skip checking for user keys in files. The
      default is “.ssh/authorized_keys
    .ssh/authorized_keys2”.AuthorizedPrincipalsCommandAuthorizedPrincipalsFile. The
      program must be owned by root, not writable by group or others and
      specified by an absolute path. Arguments to
      AuthorizedPrincipalsCommand accept the tokens
      described in the TOKENS section. If no
      arguments are specified then the username of the target user is used.
    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.
AuthorizedPrincipalsCommandUserAuthorizedPrincipalsCommand 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.AuthorizedPrincipalsFileTrustedUserCAKeys, 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 ‘#’
      are ignored.
    Arguments to AuthorizedPrincipalsFile
        accept the tokens described in the
        TOKENS section. After expansion,
        AuthorizedPrincipalsFile is taken to be an
        absolute path or one relative to the user's home directory. The default
        is none, i.e. not to use a principals file
        – 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).
Bannernone
      then no banner is displayed. By default, no banner is displayed.CASignatureAlgorithms
ssh-ed25519,ecdsa-sha2-nistp256,
ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
sk-ssh-ed25519@openssh.com,
sk-ecdsa-sha2-nistp256@openssh.com,
rsa-sha2-512,rsa-sha2-256
    
    If the specified list begins with a ‘+’ character, then the specified algorithms will be appended to the default set instead of replacing them. If the specified list begins with a ‘-’ character, then the specified algorithms (including wildcards) will be removed from the default set instead of replacing them.
Certificates signed using other algorithms will not be accepted for public key or host-based authentication.
ChannelTimeoutThe timeout value “interval” is specified in seconds or may use any of the units documented in the TIME FORMATS section. For example, “session:*=5m” would cause all sessions to terminate after five minutes of inactivity. Specifying a zero value disables the inactivity timeout.
The available channel types include:
agent-connectiondirect-tcpip,
        direct-streamlocal@openssh.comLocalForward or
          DynamicForward.forwarded-tcpip,
        forwarded-streamlocal@openssh.comRemoteForward.session:commandsession:shellsession:subsystem:...session:subsystem:sftp.x11-connectionNote that in all the above cases, terminating an inactive session does not guarantee to remove all resources associated with the session, e.g. shell processes or X11 clients relating to the session may continue to execute.
Moreover, terminating an inactive channel or session does not
        necessarily close the SSH connection, nor does it prevent a client from
        requesting another channel of the same type. In particular, expiring an
        inactive forwarding session does not prevent another identical
        forwarding from being subsequently created. See also
        UnusedConnectionTimeout, which may be used in
        conjunction with this option.
The default is not to expire channels of any type for inactivity.
ChrootDirectoryChrootDirectory accept the tokens described in the
      TOKENS section.
    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 SFTP 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 none, indicating not to
        chroot(2).
CiphersThe supported ciphers are:
The default is:
chacha20-poly1305@openssh.com,
aes128-ctr,aes192-ctr,aes256-ctr,
aes128-gcm@openssh.com,aes256-gcm@openssh.com
    
    The list of available ciphers may also be obtained using “ssh -Q cipher”.
ClientAliveCountMaxTCPKeepAlive. 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 unresponsive.
    The default value is 3. If
        ClientAliveInterval is set to 15, and
        ClientAliveCountMax is left at the default,
        unresponsive SSH clients will be disconnected after approximately 45
        seconds. Setting a zero ClientAliveCountMax
        disables connection termination.
ClientAliveIntervalCompressionyes,
      delayed (a legacy synonym for
      yes) or no. The default is
      yes.DenyGroupsDenyGroups,
      AllowGroups.
    See PATTERNS in
        ssh_config(5) for more
        information on patterns. This keyword may appear multiple times in
        sshd_config with each instance appending to the
        list.
DenyUsersDenyUsers, AllowUsers.
    See PATTERNS in
        ssh_config(5) for more
        information on patterns. This keyword may appear multiple times in
        sshd_config with each instance appending to the
        list.
DisableForwardingExposeAuthInfoSSH_USER_AUTH environment variable. The default is
      no.FingerprintHashmd5 and
      sha256. The default is
      sha256.ForceCommandForceCommand, 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 internal-sftp will force
      the use of an in-process SFTP server that requires no support files when
      used with ChrootDirectory. The default is
      none.GatewayPortsGatewayPorts 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 no to force remote port forwardings to be
      available to the local host only, yes to force
      remote port forwardings to bind to the wildcard address, or
      clientspecified to allow the client to select the
      address to which the forwarding is bound. The default is
      no.GSSAPIAuthenticationno.GSSAPICleanupCredentialsyes.GSSAPIStrictAcceptorCheckyes then
      the client must authenticate against the host service on the current
      hostname. If set to no 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 yes.HostbasedAcceptedAlgorithms
ssh-ed25519-cert-v01@openssh.com,
ecdsa-sha2-nistp256-cert-v01@openssh.com,
ecdsa-sha2-nistp384-cert-v01@openssh.com,
ecdsa-sha2-nistp521-cert-v01@openssh.com,
sk-ssh-ed25519-cert-v01@openssh.com,
sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
rsa-sha2-512-cert-v01@openssh.com,
rsa-sha2-256-cert-v01@openssh.com,
ssh-ed25519,
ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
sk-ssh-ed25519@openssh.com,
sk-ecdsa-sha2-nistp256@openssh.com,
rsa-sha2-512,rsa-sha2-256
    
    The list of available signature algorithms may also be obtained using “ssh -Q HostbasedAcceptedAlgorithms”. This was formerly named HostbasedAcceptedKeyTypes.
HostbasedAuthenticationno.HostbasedUsesNameFromPacketOnlyHostbasedAuthentication. A setting of
      yes 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 no.HostCertificateHostKey. The default behaviour of
      sshd(8) is not to load any
      certificates.HostKeyNote 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. 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).
HostKeyAgentSSH_AUTH_SOCK environment
      variable.HostKeyAlgorithms
ssh-ed25519-cert-v01@openssh.com,
ecdsa-sha2-nistp256-cert-v01@openssh.com,
ecdsa-sha2-nistp384-cert-v01@openssh.com,
ecdsa-sha2-nistp521-cert-v01@openssh.com,
sk-ssh-ed25519-cert-v01@openssh.com,
sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
rsa-sha2-512-cert-v01@openssh.com,
rsa-sha2-256-cert-v01@openssh.com,
ssh-ed25519,
ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
sk-ssh-ed25519@openssh.com,
sk-ecdsa-sha2-nistp256@openssh.com,
rsa-sha2-512,rsa-sha2-256
    
    The list of available signature algorithms may also be obtained using “ssh -Q HostKeyAlgorithms”.
IgnoreRhostsHostbasedAuthentication. The system-wide
      /etc/hosts.equiv and
      /etc/shosts.equiv are still used regardless of
      this setting.
    Accepted values are yes (the default)
        to ignore all per-user files, shosts-only to
        allow the use of .shosts but to ignore
        .rhosts or no to allow
        both .shosts and
      rhosts.
IgnoreUserKnownHostsHostbasedAuthentication and use only the
      system-wide known hosts file
      /etc/ssh/ssh_known_hosts. The default is
      “no”.IncludeInclude directive may appear inside a
      Match block to perform conditional inclusion.IPQoSaf11,
      af12, af13,
      af21, af22,
      af23, af31,
      af32, af33,
      af41, af42,
      af43, cs0,
      cs1, cs2,
      cs3, cs4,
      cs5, cs6,
      cs7, ef,
      le, lowdelay,
      throughput, reliability, a
      numeric value, or none to use the operating system
      default. 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 af21 (Low-Latency Data)
      for interactive sessions and cs1 (Lower Effort)
      for non-interactive sessions.KbdInteractiveAuthenticationyes. The argument to
      this keyword must be yes or
      no.
      ChallengeResponseAuthentication is a deprecated
      alias for this.KerberosAuthenticationPasswordAuthentication 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
      no.KerberosGetAFSTokenno.KerberosOrLocalPasswdyes.KerberosTicketCleanupyes.KexAlgorithmsThe default is:
sntrup761x25519-sha512@openssh.com,
curve25519-sha256,curve25519-sha256@libssh.org,
ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,
diffie-hellman-group-exchange-sha256,
diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,
diffie-hellman-group14-sha256
    
    The list of available key exchange algorithms may also be obtained using “ssh -Q KexAlgorithms”.
ListenAddressListenAddress
          hostname|address
          [rdomain domain]ListenAddress
          hostname:port
          [rdomain domain]ListenAddress
          IPv4_address:port
          [rdomain domain]ListenAddress
          [hostname|address]:port
          [rdomain domain]The optional rdomain qualifier
        requests sshd(8) listen in
        an explicit routing domain. 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 on the current default routing domain. Multiple
        ListenAddress options are permitted. For more
        information on routing domains, see
        rdomain(4).
LoginGraceTimeLogLevelLogVerbose
kex.c:*:1000,*:kex_exchange_identification():*,packet.c:*
    
    would enable detailed logging for line 1000 of
        kex.c, everything in the
        kex_exchange_identification() function, and all
        code in the packet.c file. This option is
        intended for debugging and no overrides are enabled by default.
MACsThe algorithms that contain “-etm” calculate the MAC after encryption (encrypt-then-mac). These are considered safer and their use recommended. The supported MACs are:
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,
hmac-sha1-etm@openssh.com,
umac-64@openssh.com,umac-128@openssh.com,
hmac-sha2-256,hmac-sha2-512,hmac-sha1
    
    The list of available MAC algorithms may also be obtained using “ssh -Q mac”.
MatchMatch 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, RDomain, and
        Address (with RDomain
        representing the
        rdomain(4) on which the
        connection was received).
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, such as 192.0.2.0/24 or 2001:db8::/32. 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, 192.0.2.0/33 and
        192.0.2.0/8, 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,
        AuthorizedPrincipalsCommand,
        AuthorizedPrincipalsCommandUser,
        AuthorizedPrincipalsFile,
        Banner,
        CASignatureAlgorithms,
        ChannelTimeout,
        ChrootDirectory,
        ClientAliveCountMax,
        ClientAliveInterval,
        DenyGroups, DenyUsers,
        DisableForwarding,
        ExposeAuthInfo,
        ForceCommand,
        GatewayPorts,
        GSSAPIAuthentication,
        HostbasedAcceptedAlgorithms,
        HostbasedAuthentication,
        HostbasedUsesNameFromPacketOnly,
        IgnoreRhosts, Include,
        IPQoS,
        KbdInteractiveAuthentication,
        KerberosAuthentication,
        LogLevel, MaxAuthTries,
        MaxSessions,
        PasswordAuthentication,
        PermitEmptyPasswords,
        PermitListen,
        PermitOpen,
        PermitRootLogin,
        PermitTTY, PermitTunnel,
        PermitUserRC,
        PubkeyAcceptedAlgorithms,
        PubkeyAuthentication,
        PubkeyAuthOptions,
        RekeyLimit, RevokedKeys,
        RDomain, SetEnv,
        StreamLocalBindMask,
        StreamLocalBindUnlink,
        TrustedUserCAKeys,
        UnusedConnectionTimeout,
        X11DisplayOffset,
        X11Forwarding and
        X11UseLocalhost.
MaxAuthTriesMaxSessionsMaxSessions to 1 will effectively disable session
      multiplexing, whereas setting it to 0 will prevent all shell, login and
      subsystem sessions while still permitting forwarding. The default is
    10.MaxStartupsLoginGraceTime
      expires for a connection. The default is 10:30:100.
    Alternatively, random early drop can be enabled by specifying the three colon separated values start:rate:full (e.g. "10:30:60"). sshd(8) will refuse connection attempts with a probability of rate/100 (30%) if there are currently start (10) unauthenticated connections. The probability increases linearly and all connection attempts are refused if the number of unauthenticated connections reaches full (60).
ModuliFilePasswordAuthenticationyes.PermitEmptyPasswordsno.PermitListenPermitListen
          portPermitListen
          host:portMultiple permissions may be specified by separating them with
        whitespace. An argument of any can be used to
        remove all restrictions and permit any listen requests. An argument of
        none can be used to prohibit all listen
        requests. The host name may contain wildcards as described in the
        PATTERNS section in
        ssh_config(5). The
        wildcard ‘*’ can also be used in place of a port number to
        allow all ports. By default all port forwarding listen requests are
        permitted. Note that the GatewayPorts option may
        further restrict which addresses may be listened on. Note also that
        ssh(1) will request a listen
        host of “localhost” if no listen host was specifically
        requested, and this name is treated differently to explicit localhost
        addresses of “127.0.0.1” and “::1”.
PermitOpenPermitOpen
          host:portPermitOpen
          IPv4_addr:portPermitOpen
          [IPv6_addr]:portMultiple forwards may be specified by separating them with
        whitespace. An argument of any can be used to
        remove all restrictions and permit any forwarding requests. An argument
        of none can be used to prohibit all forwarding
        requests. The wildcard ‘*’ can be used for host or port to
        allow all hosts or ports respectively. Otherwise, no pattern matching or
        address lookups are performed on supplied names. By default all port
        forwarding requests are permitted.
PermitRootLoginyes, prohibit-password,
      forced-commands-only, or
      no. The default is
      prohibit-password.
    If this option is set to
        prohibit-password (or its deprecated alias,
        without-password), password and
        keyboard-interactive authentication are disabled for root.
If this option is set to
        forced-commands-only, 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 no, root is
        not allowed to log in.
PermitTTYyes.PermitTunnelyes,
      point-to-point (layer 3),
      ethernet (layer 2), or no.
      Specifying yes permits both
      point-to-point and
      ethernet. The default is
      no.
    Independent of this setting, the permissions of the selected tun(4) device must allow access to the user.
PermitUserEnvironmentenvironment= options in
      ~/.ssh/authorized_keys are processed by
      sshd(8). Valid options are
      yes, no or a pattern-list
      specifying which environment variable names to accept (for example
      “LANG,LC_*”). The default is no.
      Enabling environment processing may enable users to bypass access
      restrictions in some configurations using mechanisms such as
      LD_PRELOAD.PermitUserRCyes.PerSourceMaxStartupsMaxStartups, whichever
      is lower. The default is none.PerSourceNetBlockSize32:128, which means each address is considered
      individually.PidFilenone to not write one. The default is
      /var/run/sshd.pid.PortListenAddress.PrintLastLogyes.PrintMotdyes.PubkeyAcceptedAlgorithms
ssh-ed25519-cert-v01@openssh.com,
ecdsa-sha2-nistp256-cert-v01@openssh.com,
ecdsa-sha2-nistp384-cert-v01@openssh.com,
ecdsa-sha2-nistp521-cert-v01@openssh.com,
sk-ssh-ed25519-cert-v01@openssh.com,
sk-ecdsa-sha2-nistp256-cert-v01@openssh.com,
rsa-sha2-512-cert-v01@openssh.com,
rsa-sha2-256-cert-v01@openssh.com,
ssh-ed25519,
ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,
sk-ssh-ed25519@openssh.com,
sk-ecdsa-sha2-nistp256@openssh.com,
rsa-sha2-512,rsa-sha2-256
    
    The list of available signature algorithms may also be obtained using “ssh -Q PubkeyAcceptedAlgorithms”.
PubkeyAuthOptionsnone (the default; indicating no additional
      options are enabled), touch-required and
      verify-required.
    The touch-required option causes
        public key authentication using a FIDO authenticator algorithm (i.e.
        ecdsa-sk or ed25519-sk)
        to always require the signature to attest that a physically present user
        explicitly confirmed the authentication (usually by touching the
        authenticator). By default,
        sshd(8) requires user
        presence unless overridden with an authorized_keys option. The
        touch-required flag disables this override.
The verify-required option requires a
        FIDO key signature attest that the user was verified, e.g. via a
      PIN.
Neither the touch-required or
        verify-required options have any effect for
        other, non-FIDO, public key types.
PubkeyAuthenticationyes.RekeyLimitRekeyLimit is
      default none, 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.RequiredRSASize1024 bits. Note that this limit may
      only be raised from the default.RevokedKeysnone 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).RDomain%D, then the domain in which the
      incoming connection was received will be applied.SecurityKeyProviderSetEnvSetEnv override the default environment and any
      variables specified by the user via AcceptEnv or
      PermitUserEnvironment.StreamLocalBindMaskThe 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.
StreamLocalBindUnlinkStreamLocalBindUnlink 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 yes or
        no. The default is
      no.
StrictModesyes. Note that this
      does not apply to ChrootDirectory, whose
      permissions and ownership are checked unconditionally.SubsystemThe command sftp-server implements the
        SFTP file transfer subsystem.
Alternately the name internal-sftp
        implements an in-process SFTP server. This may simplify configurations
        using ChrootDirectory to force a different
        filesystem root on clients.
By default no subsystems are defined.
SyslogFacilityTCPKeepAliveThe default is yes (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
        no.
TrustedUserCAKeysnone to not use one. Keys are listed one per line;
      empty lines and comments starting with
      ‘#’ 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).UnusedConnectionTimeout-R flag, are not considered as open channels and
      do not prevent the timeout. The timeout value is specified in seconds or
      may use any of the units documented in the
      TIME FORMATS section.
    Note that this timeout starts when the client connection completes user authentication but before the client has an opportunity to open any channels. Caution should be used when using short timeout values, as they may not provide sufficient time for the client to request and open its channels before terminating the connection.
The default none is to never expire
        connections for having no open channels. This option may be useful in
        conjunction with ChannelTimeout.
UseDNSIf this option is set to no (the
        default) then only addresses and not host names may be used in
        ~/.ssh/authorized_keys
        from and sshd_config
        Match Host
      directives.
VersionAddendumnone.X11DisplayOffsetX11Forwardingyes or no. The default is
      no.
    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), 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 no
      setting.
Note that disabling X11 forwarding does not prevent users from forwarding X11 traffic, as users can always install their own forwarders.
X11UseLocalhostDISPLAY environment variable to
      localhost. 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 no to specify that the forwarding
      server should be bound to the wildcard address. The argument must be
      yes or no. The default is
      yes.XAuthLocationnone to not use one. The default is
      /usr/X11R6/bin/xauth.UseLPKLpkLdapConfLpkServersLpkServers ldaps://127.0.0.1 ldap://127.0.0.2 ldap://127.0.0.3
LpkUserDNLpkUserDN ou=users,dc=phear,dc=org
LpkGroupDNLpkGroupDN ou=groups,dc=phear,dc=org
LpkBindDNLpkBindDN cn=Manager,dc=phear,dc=org
LpkBindPwLpkBindPw secret
LpkServerGroupLpkServerGroup unix mail prod
LpkFilterLpkFilter (hostAccess=master.phear.org)
LpkForceTLSLpkSearchTimelimitLpkSearchTimelimit 3
LpkBindTimelimitLpkBindTimelimit 3
Each member of the sequence is added together to calculate the total time value.
Time format examples:
AuthorizedKeysCommand accepts the tokens
    %%, %C, %D, %f, %h, %k, %t, %U, and %u.
AuthorizedKeysFile accepts the tokens %%,
    %h, %U, and %u.
AuthorizedPrincipalsCommand accepts the
    tokens %%, %C, %D, %F, %f, %h, %i, %K, %k, %s, %T, %t, %U, and %u.
AuthorizedPrincipalsFile accepts the
    tokens %%, %h, %U, and %u.
ChrootDirectory accepts the tokens %%, %h,
    %U, and %u.
RoutingDomain accepts the token %D.
| July 28 2023 | NetBSD 9.4 |