SSH(1)                                                     SSH(1)

     NAME
          ssh, sshnet, scp, sshserve - secure login and file copy
          from/to Unix or Plan 9

     SYNOPSIS
          ssh [ -CfiImPpRrw ] [ -A authlist ] [ -c cipherlist ] [
          -[lu] user ] [user@]host [ cmd [ args ... ]]

          sshnet [ -A authlist ] [ -c cipherlist ] [ -m mtpt ] [ -s
          service ] [user@]host

          scp [host:]file [host:]file
          scp [host:]file ... [host:]dir

          aux/sshserve [ -p ] address

     DESCRIPTION
          Ssh allows authenticated login over an encrypted channel to
          hosts that support the ssh protocol (see the RFC listed
          below for encryption and authentication details).

          Ssh takes the host name of the machine to connect to as its
          mandatory argument.  It may be specified as a domain name or
          an IP address.  Normally, login is attempted using the user
          name from /dev/user.

          Command-line options are:

          -C   force input to be read in cooked mode: ``line at a
               time'' with local echo.

          -f   enable agent forwarding.  With this flag, ssh uses
               SSH's agent forwarding protocol to allow programs run-
               ning on the remote server to interact with factotum(4)
               to perform RSA authentication.

          -i   force interactive mode.  In interactive mode, ssh
               prompts for passwords and confirmations of new host
               keys when necessary.  (In non-interactive mode, pass-
               word requests are rejected and unrecognized host keys
               are cause for disconnecting.)  By default, ssh runs in
               interactive mode only when its input file descriptor is
               /dev/cons.

          -I   force non-interactive mode.

          -m   disable the control-\ menu, described below.

          -p   force pseudoterminal request.  The ssh protocol,
               grounded in Unix tradition, differentiates between

     SSH(1)                                                     SSH(1)

               connections that request controlling pseudoterminals
               and those that do not.  By default, ssh requests a
               pseudoterminal only when no command is given.

          -P   force no pseudoterminal request.

          -r   strip carriage returns.

          -R   put the allocated pseudoterminal, if any, in raw mode.

          -w   notify the remote side whenever the window changes
               size.

          -[lu] user
               specify user name.  This option is deprecated in favor
               of the user@hostname syntax.

          -A authlist
               specify an ordered space-separated list of authentica-
               tion protocols to try.  The full set of authentication
               protocols is rsa (RSA using factotum(4) to moderate key
               usage), password (use a password gathered from facto-
               tum), and tis (challenge-response).  The default list
               is all three in that order.

          -c cipherlist
               specify an ordered space-separated list of allowed
               ciphers to use when encrypting the channel.  The full
               set of ciphers is des (standard DES), 3des (a somewhat
               doubtful variation on triple DES), blowfish (Bruce
               Schneier's Blowfish), rc4 (RC4), and none (no encryp-
               tion).  The default cipher list is blowfish rc4 3des.

          The control-\ character is a local escape, as in con(1). It
          prompts with >>>.  Legitimate responses to the prompt are

          q    Exit.

          .    Return from the escape.

          !cmd Run the command with the network connection as its
               standard input and standard output.  Standard error
               will go to the screen.

          r    Toggle printing of carriage returns.

          If no command is specified, a login session is started on
          the remote host.  Otherwise, the command is executed with
          its arguments.

          Ssh establishes a connection with an ssh daemon on the
          remote host.  The daemon sends to ssh its RSA public host

     SSH(1)                                                     SSH(1)

          key and session key.  Using these, ssh sends a session key
          which, presumably, only the daemon can decipher.  After
          this, both sides start encrypting their data with this ses-
          sion key.

          When the daemon's host key has been received, ssh looks it
          up in $home/lib/keyring and in /sys/lib/ssh/keyring.  If the
          key is found there, and it matches the received key, ssh is
          satisfied.  If not, ssh reports this and offers to add the
          key to $home/lib/keyring.

          Over the encrypted channel, ssh attempts to convince the
          daemon to accept the call using the listed authentication
          protocols (see the -A option above).

          The preferred way to authenticate is a netkey-style
          challenge/response or via a SecurID token.  Ssh users on
          other systems than Plan 9 should enable TIS_Authentication.

          When the connection is authenticated, the given command
          line, (by default, a login shell) is executed on the remote
          host.

          The SSH protocol allows clients to make outgoing TCP calls
          via the server.  Sshnet establishes an SSH connection and,
          rather than execute a remote command, presents the remote
          server's TCP stack as a network stack (see the discussion of
          TCP in ip(3)) mounted at mtpt (default /net), optionally
          posting a 9P service descriptor for the new file system as
          /srv/service.  The -A and -c arguments are as in ssh.

          Scp uses ssh to copy files from one host to another.  A
          remote file is identified by a host name, a colon and a file
          name (no spaces).  Scp can copy files from remote hosts and
          to remote hosts.

          Sshserve is the server that services ssh calls from remote
          hosts. The -A and -c options set valid authentication meth-
          ods and ciphers as in ssh, except that there is no rsa
          authentication method.  Unlike in ssh, the list is not
          ordered: the server presents a set and the client makes the
          choice.  The default sets are tis and blowfish rc4 3des.  By
          default, users start with the namespace defined in
          /lib/namespace.  Users in group noworld in /adm/users start
          with the namespace defined in /lib/namespace.noworld.
          Sshserve does not provide the TCP forwarding functionality
          used by sshnet, because many Unix clients present this capa-
          bility in an insecure manner.

          Sshserve requires that factotum(4) hold the host key, iden-
          tified by having attributes proto=rsa service=sshserve.  To
          generate a host key:

     SSH(1)                                                     SSH(1)

               auth/rsagen -t 'service=sshserve' >/mnt/factotum/ctl

          To extract the public part of the host key in the form used
          by SSH key rings:

               grep 'service=sshserve' /mnt/factotum/ctl | auth/rsa2ssh

     FILES
          /sys/lib/ssh/keyring
               System key ring file containing public keys for remote
               ssh clients and servers.

          /usr/user/lib/keyring
               Personal key ring file containing public keys for
               remote ssh clients and servers.

     SOURCE
          /sys/src/cmd/ssh

     SEE ALSO
          factotum(4), authsrv(6), rsa(8)