rcmd(3X)                       DG/UX R4.11MU05                      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;
       u_short inport;
       char *locuser, *remuser, *cmd;
       int *fd2p;

       s = rresvport(port);
       int *port;

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

DESCRIPTION
       rcmd is a routine used by a user with appropriate privilege (See
       NOTES, below) 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 consist of a port in the
       range 0 to 1023.  Only a user with appropriate privilege 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 that of a privileged user or administrative.  It then checks
       the files /etc/hosts.equiv and, possibly, .rhosts in 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 privileged_user flag is 1, the
       checking of the ``host.equiv'' file is bypassed.

SEE ALSO
       rlogin(1C), rsh(1C), rexecd(1M), rlogind(1M), rexec(3X)i,
       appropriate_privilege(5).
       cap_defaults(5).

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

       On a traditional DG/UX system, appropriate privilege is granted by
       having an effective UID of 0 (root).  See the
       appropriate_privilege(5) man page for more information.

       On a system with DG/UX information security, appropriate privilege is
       granted by having one or more specific capabilities enabled in the
       effective capability set of the user.  See cap_defaults(5) for the
       default capabilities for this command.



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