.\" $OpenBSD: login_skey.8,v 1.8 2004/08/05 13:37:06 millert Exp $
.\"
.\" Copyright (c) 2000, 2002 Todd C. Miller <Todd.Miller@courtesan.com>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
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.\" copyright notice and this permission notice appear in all copies.
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.\" Sponsored in part by the Defense Advanced Research Projects
.\" Agency (DARPA) and Air Force Research Laboratory, Air Force
.\" Materiel Command, USAF, under agreement number F39502-99-1-0512.
.\"
.Dd July 26, 2004
.Dt LOGIN_SKEY 8
.Os
.Sh NAME
.Nm login_skey
.Nd provide S/Key authentication type
.Sh SYNOPSIS
.Nm login_skey
.Op Fl s Ar service
.Op Fl v Ar fd=number
.Ar user
.Op Ar class
.Sh DESCRIPTION
The
.Nm
utility is called by
.Xr login 1 ,
.Xr su 1 ,
.Xr ftpd 8 ,
and others to authenticate the
.Ar user
with S/Key authentication.
.Pp
The
.Ar service
argument specifies which protocol to use with the
invoking program.
The allowed protocols are
.Em login ,
.Em challenge ,
and
.Em response .
The default protocol is
.Em login .
.Pp
The
.Ar fd
argument is used to specify the number of an open, locked file descriptor
that references the user's S/Key entry.
This is used to prevent simultaneous S/Key authorization attempts from
using the same challenge.
.Pp
The
.Ar user
argument is the login name of the user to be authenticated.
.Pp
The optional
.Ar class
argument is accepted for consistency with the other login scripts but
is not used.
.Pp
.Nm
will look up
.Ar user
in the S/Key database and, depending on the desired protocol,
will do one of three things:
.Bl -tag -width challenge
.It login
Present
.Ar user
with an S/Key challenge, accept a response and report back to the
invoking program whether or not the authentication was successful.
.It challenge
Return the current S/Key challenge for
.Ar user .
.It response
Report back to the invoking program whether or not the specified
response matches the current S/Key challenge for
.Ar user .
.El
.Pp
If
.Ar user
does not have an entry in the S/Key database, a fake challenge will
be generated by the S/Key library.
.Sh FILES
.Bl -tag -width /etc/skey
.It Pa /etc/skey
directory containing user entries for S/Key
.El
.Sh SEE ALSO
.Xr login 1 ,
.Xr skey 1 ,
.Xr skeyinfo 1 ,
.Xr skeyinit 1 ,
.Xr login.conf 5 ,
.Xr ftpd 8