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



NAME
       rexec, rexec_af - return stream to a remote command

SYNOPSIS
       #include <netdb.h>

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

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

       rexec(), rexec_af():
	   Since glibc 2.19:
	       _DEFAULT_SOURCE
	   In glibc up to and including 2.19:
	       _BSD_SOURCE

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  .netrc file in user's 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  getser-
       vent(3))	 will return a pointer to a structure that contains the neces-
       sary port.  The protocol for connection is described in detail in  rex-
       ecd(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 file 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
       caller 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
       For  an	explanation  of	 the  terms  used   in	 this	section,   see
       attributes(7).

       +--------------------+---------------+-----------+
       |Interface	    | Attribute	    | Value	|
       +--------------------+---------------+-----------+
       |rexec(), rexec_af() | Thread safety | MT-Unsafe |
       +--------------------+---------------+-----------+
CONFORMING TO
       These  functions	 are  not  in  POSIX.1.	  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 4.10 of the Linux  man-pages  project.   A
       description  of	the project, information about reporting bugs, and the
       latest	 version    of	  this	  page,	   can	   be	  found	    at
       https://www.kernel.org/doc/man-pages/.



Linux				  2016-03-15			      REXEC(3)