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, 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);
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
getservent(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 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¶
Multithreading (see pthreads(7))¶
The
rexec() and
rexec_af() functions are not thread-safe.
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 3.74 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
http://www.kernel.org/doc/man-pages/.
