telnetlogin.8

这是关于远程登陆TELNET 的源代码 已经测试过的。

.\" Copyright (c) 2000 David A. Holland.
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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
.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 
.Nm telnetd 8
normally provides them in.
.Nm telnetlogin
also only accepts the environment variables
.Ev TERM , 
.Ev DISPLAY , 
.Ev POSIXLY_CORRECT ,
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, and does not permit passing a username, 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.