REXEC(3)						     Linux Programmer's Manual							  REXEC(3)

NAME

       rexec, rexec_af - return stream to a remote command

SYNOPSIS

       #define _BSD_SOURCE	       /* See feature_test_macros(7) */
       #include <netdb.h>

       int rexec(char **ahost, int inport, char *user,
		 char *passwd, char *cmd, int *fd2p);

       int rexec_af(char **ahost, int inport, char *user,
		    char *passwd, char *cmd, int *fd2p,
		    sa_family_t af);

DESCRIPTION

       This interface is obsoleted by rcmd(3).

       The  rexec() function looks up the host *ahost using gethostbyname(3), returning -1 if the host does not exist.	Otherwise *ahost is set to
       the standard name of the host.  If a username and password are both specified, then these are used to authenticate  to  the  foreign  host;
       otherwise  the  environment  and  then  the user's .netrc file in his home directory are searched for appropriate information.  If all this
       fails, the user is prompted for the information.

       The port inport specifies which well-known DARPA Internet port to use for the connection; the call getservbyname("exec", "tcp")	(see  get-
       servent(3))  will  return a pointer to a structure that contains the necessary port.  The protocol for connection is described in detail in
       rexecd(8).

       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 nonzero, then an auxiliary channel to a control process will be setup, 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.  The diagnostic information returned
       does not include remote authorization failure, as the secondary connection is set up after authorization has been verified.  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.

   rexec_af()
       The rexec() function works over IPv4 (AF_INET).	By contrast, the rexec_af() function provides an extra argument, af, that allows the call-
       er  to  select  the protocol.  This argument can be specified as AF_INET, AF_INET6, or AF_UNSPEC (to allow the implementation to select the
       protocol).

VERSIONS

       The rexec_af() function was added to glibc in version 2.2.

ATTRIBUTES

   Multithreading (see pthreads(7))
       The rexec() and rexec_af() functions are not thread-safe.

CONFORMING TO

       These functions are not in POSIX.1-2001.  The rexec() function first appeared in 4.2BSD, and is present on  the	BSDs,  Solaris,  and  many
       other systems.  The rexec_af() function is more recent, and less widespread.

BUGS

       The rexec() function sends the unencrypted password across the network.

       The underlying service is considered a big security hole and therefore not enabled on many sites; see rexecd(8) for explanations.

SEE ALSO

       rcmd(3), rexecd(8)

COLOPHON

       This  page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2013-07-04								  REXEC(3)