rcmd(3X)                   DG/UX 4.31                    rcmd(3X)



     NAME
          rcmd, rresvport, ruserok - routines for returning a stream
          to a remote command

     SYNOPSIS
          rem = rcmd(ahost, inport, locuser, remuser, cmd, fd2p);
          char **ahost;
          ushort inport;
          char *locuser, *remuser, *cmd;
          int *fd2p;

          s = rresvport(port);
          int *port;

          ruserok(rhost, superuser, ruser, luser);
          char *rhost;
          int superuser;
          char *ruser, *luser;

     DESCRIPTION
          Rcmd is a routine used by the super-user to execute a
          command on a remote machine using an authentication scheme
          based on reserved port numbers.  Rresvport is a routine
          which returns a descriptor to a socket with an address in
          the privileged port space.  Ruserok is a routine used by
          servers to authenticate clients requesting service with
          rcmd.

          Rcmd looks up the host *ahost using gethostbyname(3N),
          returning -1 if the host does not exist.  Otherwise *ahost
          is set to the standard name of the host and a connection is
          established to a server residing at the well-known Internet
          port inport.

          If the call succeeds, a socket of type SOCK_STREAM is
          returned to the caller, and given to the remote command as
          stdin and stdout.  If fd2p is non-zero, then an auxiliary
          channel to a control process will be set up, and a
          descriptor for it will be placed in *fd2p.  The control
          process will return diagnostic output from the command (unit
          2) on this channel, and will also accept bytes on this
          channel as being DG/UX system signal numbers, to be
          forwarded to the process group of the command.  If fd2p is
          0, then the stderr (unit 2 of the remote command) will be
          made the same as the stdout and no provision is made for
          sending arbitrary signals to the remote process, although
          you may be able to get its attention by using out-of-band
          data.

          The rresvport routine is used to obtain a socket with a
          privileged address bound to it.  This socket is suitable for
          use by rcmd and sevral other routines.  Privileged addresses



     Licensed material--property of copyright holder(s)         Page 1

     rcmd(3X)                   DG/UX 4.31                    rcmd(3X)



          consist of a port in the range 0 to 1023.  Only the super-
          user is allowed to bind an address of this sort to a socket.

          Ruserok takes a remote host's name, as returned by a
          gethostent(3N) routine, two user names and a flag indicating
          if the local user's name is the super-user.  It then checks
          the files /etc/hosts.equiv and, possibly, .rhosts in the
          current working directory (normally the local user's home
          directory) to see if the request for service is allowed.  A
          0 is returned if the machine name is listed in the
          ``hosts.equiv'' file, or the host and remote user name are
          found in the ``.rhosts'' file; otherwise ruserok returns -1.
          If the superuser flag is 1, the checking of the
          ``host.equiv'' file is bypassed.

     SEE ALSO
          rlogin(1C), rsh(1C), rexec(3X), rexecd(8C), rlogind(8C),

     NOTE
          There is no way to specify options to the socket call that
          rcmd makes.


































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