-and
-.Ql ?
-can be used as wildcards in 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.
-.It Cm GatewayPorts
-Specifies whether remote hosts are allowed to connect to ports
-forwarded for the client.
-By default,
-.Nm
-binds remote port forwardings to the loopback addresss. This
-prevents other remote hosts from connecting to forwarded ports.
-.Cm GatewayPorts
-can be used to specify that
-.Nm
-should bind remote port forwardings to the wildcard address,
-thus allowing remote hosts to connect to forwarded ports.
-The argument must be
-.Dq yes
-or
-.Dq no .
-The default is
-.Dq no .
-.It Cm HostbasedAuthentication
-Specifies whether rhosts or /etc/hosts.equiv authentication together
-with successful public key client host authentication is allowed
-(hostbased authentication).
-This option is similar to
-.Cm RhostsRSAAuthentication
-and applies to protocol version 2 only.
-The default is
-.Dq no .
-.It Cm HostKey
-Specifies a file containing a private host key
-used by SSH.
-The default is
-.Pa /etc/ssh/ssh_host_key
-for protocol version 1, and
-.Pa /etc/ssh/ssh_host_rsa_key
-and
-.Pa /etc/ssh/ssh_host_dsa_key
-for protocol version 2.
-Note that
-.Nm
-will refuse to use a file if it is group/world-accessible.
-It is possible to have multiple host key files.
-.Dq rsa1
-keys are used for version 1 and
-.Dq dsa
-or
-.Dq rsa
-are used for version 2 of the SSH protocol.
-.It Cm IgnoreRhosts
-Specifies that
-.Pa .rhosts
-and
-.Pa .shosts
-files will not be used in
-.Cm RhostsAuthentication ,
-.Cm RhostsRSAAuthentication
-or
-.Cm HostbasedAuthentication .
-.Pp
-.Pa /etc/hosts.equiv
-and
-.Pa /etc/shosts.equiv
-are still used.
-The default is
-.Dq yes .
-.It Cm IgnoreUserKnownHosts
-Specifies whether
-.Nm
-should ignore the user's
-.Pa $HOME/.ssh/known_hosts
-during
-.Cm RhostsRSAAuthentication
-or
-.Cm HostbasedAuthentication .
-The default is
-.Dq no .
-.It Cm KeepAlive
-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 keepalives are not sent,
-sessions may hang indefinitely on the server, leaving
-.Dq ghost
-users and consuming server resources.
-.Pp
-The default is
-.Dq yes
-(to send keepalives), and the server will notice
-if the network goes down or the client host crashes.
-This avoids infinitely hanging sessions.
-.Pp
-To disable keepalives, the value should be set to
-.Dq no .
-.It Cm KerberosAuthentication
-Specifies whether Kerberos authentication is allowed.
-This can be in the form of a Kerberos ticket, or if
-.Cm PasswordAuthentication
-is yes, the password provided by the user 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.
-Default is
-.Dq yes .
-.It Cm KerberosOrLocalPasswd
-If set then if password authentication through Kerberos fails then
-the password will be validated via any additional local mechanism
-such as
-.Pa /etc/passwd .
-Default is
-.Dq yes .
-.It Cm KerberosTgtPassing
-Specifies whether a Kerberos TGT may be forwarded to the server.
-Default is
-.Dq no ,
-as this only works when the Kerberos KDC is actually an AFS kaserver.
-.It Cm KerberosTicketCleanup
-Specifies whether to automatically destroy the user's ticket cache
-file on logout.
-Default is
-.Dq yes .
-.It Cm 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).
-.It Cm ListenAddress
-Specifies the local addresses
-.Nm
-should listen on.
-The following forms may be used:
-.Pp
-.Bl -item -offset indent -compact
-.It
-.Cm ListenAddress
-.Sm off
-.Ar host No | Ar IPv4_addr No | Ar IPv6_addr
-.Sm on
-.It
-.Cm ListenAddress
-.Sm off
-.Ar host No | Ar IPv4_addr No : Ar port
-.Sm on
-.It
-.Cm ListenAddress
-.Sm off
-.Oo
-.Ar host No | Ar IPv6_addr Oc : Ar port
-.Sm on
-.El
-.Pp
-If
-.Ar port
-is not specified,
-.Nm
-will listen on the address and all prior
-.Cm Port
-options specified. The default is to listen on all local
-addresses. Multiple
-.Cm ListenAddress
-options are permitted. Additionally, any
-.Cm Port
-options must precede this option for non port qualified addresses.
-.It Cm 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 600 (seconds).
-.It Cm LogLevel
-Gives the verbosity level that is used when logging messages from
-.Nm sshd .
-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.
-.It Cm 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.
-The default is
-.Dq hmac-md5,hmac-sha1,hmac-ripemd160,hmac-sha1-96,hmac-md5-96 .
-.It Cm MaxStartups
-Specifies the maximum number of concurrent unauthenticated connections to the
-.Nm
-daemon.
-Additional connections will be dropped until authentication succeeds or the
-.Cm LoginGraceTime
-expires for a connection.
-The default is 10.
-.Pp
-Alternatively, random early drop can be enabled by specifying
-the three colon separated values
-.Dq start:rate:full
-(e.g., "10:30:60").
-.Nm
-will refuse connection attempts with a probability of
-.Dq rate/100
-(30%)
-if there are currently
-.Dq start
-(10)
-unauthenticated connections.
-The probability increases linearly and all connection attempts
-are refused if the number of unauthenticated connections reaches
-.Dq full
-(60).
-.It Cm PAMAuthenticationViaKbdInt
-Specifies whether PAM challenge response authentication is allowed. This
-allows the use of most PAM challenge response authentication modules, but
-it will allow password authentication regardless of whether
-.Cm PasswordAuthentication
-is disabled.
-The default is
-.Dq no .
-.It Cm PasswordAuthentication
-Specifies whether password authentication is allowed.
-The default is
-.Dq yes .
-.It Cm PermitEmptyPasswords
-When password authentication is allowed, it specifies whether the
-server allows login to accounts with empty password strings.
-The default is
-.Dq no .
-.It Cm PermitRootLogin
-Specifies whether root can login using
-.Xr ssh 1 .
-The argument must be
-.Dq yes ,
-.Dq without-password ,
-.Dq forced-commands-only