rcmd(3) [bsd man page]

RCMD(3) 						     Library Functions Manual							   RCMD(3)

NAME

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

SYNOPSIS

       rem = rcmd(ahost, inport, locuser, remuser, cmd, fd2p);
       char **ahost;
       int 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.  All three functions are present in the same file and are used by the
       rshd(8C) server (among others).

       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 connection succeeds, a socket in the Internet domain 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 UNIX 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 protocol is described in detail in rshd(8C).

       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  sev-
       eral  other  routines.	Privileged  Internet ports are those 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 gethostbyaddr(3N) routine, two user names and a  flag  indicating  whether	the  local
       user's  name  is that of 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 supe-
       ruser flag is 1, the checking of the ``host.equiv'' file is bypassed.  If the local domain (as obtained from gethostname(2)) is the same as
       the remote domain, only the machine name need be specified.

SEE ALSO

       rlogin(1C), rsh(1C), intro(2), rexec(3), rexecd(8C), rlogind(8C), rshd(8C)

DIAGNOSTICS

       Rcmd returns a valid socket descriptor on success.  It returns -1 on error and prints a diagnostic message on the standard error.

       Rresvport  returns  a  valid,  bound socket descriptor on success.  It returns -1 on error with the global value errno set according to the
       reason for failure.  The error code EAGAIN is overloaded to mean ``All network ports in use.''

4.2 Berkeley Distribution					   May 14, 1986 							   RCMD(3)

RCMD(3) 						     Library Functions Manual							   RCMD(3)

NAME

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

SYNOPSIS

       rem = rcmd(ahost, inport, locuser, remuser, cmd, fd2p);
       char **ahost;
       int 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.  All three functions are present in the same file and are used by the
       rshd(8C) server (among others).

       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 connection succeeds, a socket in the Internet domain 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 UNIX 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 protocol is described in detail in rshd(8C).

       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  sev-
       eral  other  routines.	Privileged  Internet ports are those 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 gethostbyaddr(3N) routine, two user names and a  flag  indicating  whether	the  local
       user's  name  is that of 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 supe-
       ruser flag is 1, the checking of the ``host.equiv'' file is bypassed.  If the local domain (as obtained from gethostname(2)) is the same as
       the remote domain, only the machine name need be specified.

SEE ALSO

       rlogin(1C), rsh(1C), intro(2), rexec(3), rexecd(8C), rlogind(8C), rshd(8C)

DIAGNOSTICS

       Rcmd returns a valid socket descriptor on success.  It returns -1 on error and prints a diagnostic message on the standard error.

       Rresvport  returns  a  valid,  bound socket descriptor on success.  It returns -1 on error with the global value errno set according to the
       reason for failure.  The error code EAGAIN is overloaded to mean ``All network ports in use.''

4.2 Berkeley Distribution					   May 14, 1986 							   RCMD(3)