1.\" Copyright (c) 2001 Mark R V Murray 2.\" Copyright (c) 2001-2003 Networks Associates Technology, Inc. 3.\" Copyright (c) 2004-2011 Dag-Erling Smørgrav 4.\" All rights reserved. 5.\" 6.\" This software was developed for the FreeBSD Project by ThinkSec AS and 7.\" NAI Labs, the Security Research Division of Network Associates, Inc. 8.\" under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 9.\" DARPA CHATS research program. 10.\" 11.\" Redistribution and use in source and binary forms, with or without 12.\" modification, are permitted provided that the following conditions 13.\" are met: 14.\" 1. Redistributions of source code must retain the above copyright 15.\" notice, this list of conditions and the following disclaimer. 16.\" 2. Redistributions in binary form must reproduce the above copyright 17.\" notice, this list of conditions and the following disclaimer in the 18.\" documentation and/or other materials provided with the distribution. 19.\" 3. The name of the author may not be used to endorse or promote 20.\" products derived from this software without specific prior written 21.\" permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" $FreeBSD$ 36.\" 37.Dd October 7, 2011 38.Dt PAM_SSH 8 39.Os 40.Sh NAME 41.Nm pam_ssh 42.Nd authentication and session management with SSH private keys 43.Sh SYNOPSIS 44.Op Ar service-name 45.Ar module-type 46.Ar control-flag 47.Pa pam_ssh 48.Op Ar options 49.Sh DESCRIPTION 50The 51SSH 52authentication service module for PAM, 53.Nm 54provides functionality for two PAM categories: 55authentication 56and session management. 57In terms of the 58.Ar module-type 59parameter, they are the 60.Dq Li auth 61and 62.Dq Li session 63features. 64.Ss SSH Authentication Module 65The 66SSH 67authentication component 68provides a function to verify the identity of a user 69.Pq Fn pam_sm_authenticate , 70by prompting the user for a passphrase and verifying that it can 71decrypt the target user's SSH key using that passphrase. 72.Pp 73The following options may be passed to the authentication module: 74.Bl -tag -width ".Cm use_first_pass" 75.It Cm use_first_pass 76If the authentication module 77is not the first in the stack, 78and a previous module 79obtained the user's password, 80that password is used 81to authenticate the user. 82If this fails, 83the authentication module returns failure 84without prompting the user for a password. 85This option has no effect 86if the authentication module 87is the first in the stack, 88or if no previous modules 89obtained the user's password. 90.It Cm try_first_pass 91This option is similar to the 92.Cm use_first_pass 93option, 94except that if the previously obtained password fails, 95the user is prompted for another password. 96.It Cm nullok 97Normally, keys with no passphrase are ignored for authentication 98purposes. 99If this option is set, keys with no passphrase will be taken into 100consideration, allowing the user to log in with a blank password. 101.El 102.Ss SSH Session Management Module 103The 104SSH 105session management component 106provides functions to initiate 107.Pq Fn pam_sm_open_session 108and terminate 109.Pq Fn pam_sm_close_session 110sessions. 111The 112.Fn pam_sm_open_session 113function starts an SSH agent, 114passing it any private keys it decrypted 115during the authentication phase, 116and sets the environment variables 117the agent specifies. 118The 119.Fn pam_sm_close_session 120function kills the previously started SSH agent 121by sending it a 122.Dv SIGTERM . 123.Pp 124The following options may be passed to the session management module: 125.Bl -tag -width ".Cm want_agent" 126.It Cm want_agent 127Start an agent even if no keys were decrypted during the 128authentication phase. 129.El 130.Sh FILES 131.Bl -tag -width ".Pa $HOME/.ssh/identity" -compact 132.It Pa $HOME/.ssh/identity 133SSH1 RSA key 134.It Pa $HOME/.ssh/id_rsa 135SSH2 RSA key 136.It Pa $HOME/.ssh/id_dsa 137SSH2 DSA key 138.It Pa $HOME/.ssh/id_ecdsa 139SSH2 ECDSA key 140.El 141.Sh SEE ALSO 142.Xr ssh-agent 1 , 143.Xr pam.conf 5 , 144.Xr pam 8 145.Sh AUTHORS 146The 147.Nm 148module was originally written by 149.An -nosplit 150.An Andrew J. Korty Aq Mt ajk@iu.edu . 151The current implementation was developed for the 152.Fx 153Project by 154ThinkSec AS and NAI Labs, the Security Research Division of Network 155Associates, Inc.\& under DARPA/SPAWAR contract N66001-01-C-8035 156.Pq Dq CBOSS , 157as part of the DARPA CHATS research program. 158This manual page was written by 159.An Mark R V Murray Aq Mt markm@FreeBSD.org . 160