libcompat/4.3/rexec.3

.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd June 4, 1993
.Dt REXEC 3
.Os
.Sh NAME
.Nm rexec
.Nd return stream to a remote command
.Sh LIBRARY
.Lb libcompat
.Sh SYNOPSIS
.Ft int
.Fn rexec "char **ahost" "int inport" "char *user" "char *passwd" "char *cmd" "int *fd2p"
.Sh DESCRIPTION
.Bf -symbolic
This interface is obsoleted by
.Xr rcmd 3 .
.Ef
.Pp
The
.Fn rexec
function
looks up the host
.Fa *ahost
using
.Xr gethostbyname 3 ,
returning \-1 if the host does not exist.
Otherwise
.Fa *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
.Pa .netrc
file in his
home directory are searched for appropriate information.
If all this fails, the user is prompted for the information.
.Pp
The port
.Fa inport
specifies which well-known
.Tn DARPA
Internet port to use for
the connection; the call
.Fn getservbyname \*qexec\*q \*qtcp\*q
(see
.Xr getservent 3 )
will return a pointer to a structure, which contains the
necessary port.
The protocol for connection is described in detail in
.Xr rexecd 8 .
.Pp
If the connection succeeds,
a socket in the Internet domain of type
.Dv SOCK_STREAM
is returned to
the caller, and given to the remote command as
.Dv stdin
and
.Dv stdout .
If
.Fa fd2p
is non-zero, then an auxiliary channel to a control
process will be setup, and a descriptor for it will be placed
in
.Fa *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
.Ux
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
.Fa fd2p
is 0, then the
.Dv stderr
(unit 2 of the remote
command) will be made the same as the
.Dv 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.
.Sh SEE ALSO
.Xr rcmd 3 ,
.Xr rexecd 8
.Sh HISTORY
The
.Fn rexec
function appeared in
.Bx 4.2 .
.Sh BUGS
The
.Fn rexec
function sends the unencrypted password across the network.
.Pp
The underlying service is considered a big security hole and therefore
not enabled on many sites, see
.Xr rexecd 8
for explanations.