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.\"	@(#)rlogind.8	6.4 (Berkeley) 9/19/88
.\"
.TH KLOGIND 8 "Kerberos Version 4.0" "MIT Project Athena"
.UC 5
.SH NAME
klogind \- remote login server
.SH SYNOPSIS
.B /usr/etc/klogind
.br
.B /usr/etc/Klogind
.br
.B /usr/etc/eklogind
.SH DESCRIPTION
.I Klogind
is the server for the Kerberos version of the
.IR rlogin (1)
program.  The server provides a remote login facility
with authentication provided by Kerberos.
.PP
.I Klogind
listens for service requests at the port indicated in
the ``klogin'' or ``eklogin'' service specification; see
.IR services (5).
.PP
Invocation as Klogind is intended for secure
hosts to which no password access will be granted; invocation as klogind
is intended for normal hosts to which password access may be granted if
Kerberos authorization fails; invocation as eklogind provides an
encrypted communications channel.  A host can run either Klogind or
klogind but not both (they use the same port, ``klogin'').  Eklogind may
be run independently.
.PP
When a service request is received, the server checks the client's
source address and requests the corresponding host name (see
.IR gethostbyaddr (3N),
.IR hosts (5)
and
.IR named (8)).
If the hostname cannot be determined,
the dot-notation representation of the host address is used.
.PP
Once the source address has been checked, 
.I klogind
allocates a pseudo terminal (see 
.IR pty (4)),
and manipulates file descriptors so that the slave
half of the pseudo terminal becomes the 
.B stdin ,
.B stdout ,
and
.B stderr 
for a login process.
The login process is an instance of the
.IR login (1)
program, invoked with the
.B \-k,
.B \-K,
or
.B \-e
option, depending on whether the klogind was started as klogind, Klogind
or eklogind, respectively.
The login process then proceeds with the
authentication process as described in
.IR kshd (8),
but if automatic authentication fails, it reprompts the user
to login as one finds on a standard terminal line.
.PP
The parent of the login process manipulates the master side of
the pseudo terminal, operating as an intermediary
between the login process and the client instance of the
.I rlogin
program.  If klogind is invoked as eklogind, all data passed over
the network are encrypted.
In normal operation, the packet protocol described
in
.IR pty (4)
is invoked to provide ^S/^Q type facilities and propagate
interrupt signals to the remote programs.  The login process
propagates the client terminal's baud rate and terminal type,
as found in the environment variable, ``TERM''; see
.IR environ (7).
The screen or window size of the terminal is requested from the client,
and window size changes from the client are propagated to the pseudo terminal.
.SH DIAGNOSTICS
All diagnostic messages are returned on the connection
associated with the
.BR stderr ,
after which any network connections are closed.
An error is indicated by a leading byte with a value of 1.
.PP
.B ``Try again.''
.br
A
.I fork
by the server failed.
.PP
.B ``/bin/sh: ...''
.br
The user's login shell could not be started.
.SH SEE ALSO
kerberos(3)
.SH BUGS
.PP
A more extensible protocol should be used.