.\" Copyright (c) 2000 David A. Holland.
.\" 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. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by David A. Holland.
.\" 4. Neither the name of the Author nor the names of any contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND ANY 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 AUTHOR OR ANY CONTRIBUTORS BE LIABLE
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\"
.\"	$Id: telnetlogin.8,v 1.4 2000/07/30 23:57:10 dholland Exp $
.\"
.Dd April 12, 2000
.Dt TELNETLOGIN 8
.Os "Linux NetKit (0.17)"
.Sh NAME
.Nm telnetlogin
.Nd login wrapper for telnetd
.Sh SYNOPSIS
.Nm telnetlogin
.Op Fl h Ar host
.Op Fl p
.Op Ar username
.Sh DESCRIPTION
.Nm telnetlogin
is a setuid wrapper that runs
.Xr login 1 .
It is meant to be invoked by
.Xr telnetd 8 ;
the idea is to remove the necessity of running telnetd as root.
.Pp
.Nm telnetlogin
should be installed mode 4750, user root, group telnetd. Then,
telnetd may be run from
.Pa /etc/inetd.conf
as user ``nobody'', group ``telnetd'', and with the option
.Fl L Ar path-to-telnetlogin .
.Pp
.Nm telnetlogin
accepts only the subset of options to
.Xr login 1
shown above, in the order listed. This is the order 
.Xr telnetd 8
normally provides them in.
.Nm telnetlogin
also does sanity checks on the environment variables
.Ev TERM , 
and
.Ev REMOTEHOST .
It also insists that the standard input, output, and error streams are
open on a terminal, and that it is the process group leader of the
foreground process of that terminal. After checking all of these
conditions, checking the values of the above environment variables for
reasonable values, resetting signal handlers, and so forth, it execs
login.
.Sh SEE ALSO
.Xr login 1 ,
.Xr inetd.conf 5 ,
.Xr inetd 8 ,
.Xr telnetd 8
.Sh RESTRICTIONS
.Nm telnetlogin
does not permit the
.Fl f
option to login, so will not
work with telnetds that perform authentication via Kerberos or SSL.
.Pp
THIS IS PRESENTLY EXPERIMENTAL CODE; USE WITH CAUTION.
.Sh HISTORY
.Nm telnetlogin
was written during the development of NetKit 0.17.