pam_ssh (8) - Linux Manuals

pam_ssh: authentication and session management with SSH private keys

NAME

pam_ssh - authentication and session management with SSH private keys

SYNOPSIS

[service-name ] module-type control-flag pam_ssh [options ]

DESCRIPTION

The SSH authentication service module for PAM, provides functionality for two PAM categories: authentication and session management. In terms of the module-type parameter, they are the ``auth '' and ``session '' features. It also provides null functions for the remaining categories.

SSH Authentication Module

The SSH authentication component provides a function to verify the identity of a user (Fn pam_sm_authenticate ) by prompting the user for a passphrase and verifying that it can decrypt the target user's SSH key using that passphrase.

The following options may be passed to the authentication module:

debug

syslog(3) debugging information at LOG_DEBUG level.

use_first_pass

If the authentication module is not the first in the stack, and a previous module obtained the user's password, that password is used to authenticate the user. If this fails, the authentication module returns failure without prompting the user for a password. This option has no effect if the authentication module is the first in the stack, or if no previous modules obtained the user's password.

try_first_pass

This option is similar to the use_first_pass option, except that if the previously obtained password fails, the user is prompted for another password.

keyfiles

Specify the comma-separated list of files in $HOME/.ssh to check for SSH keys. The default is ``id_dsa,id_rsa,identity''

nullok

Allow empty passphrases.

SSH Session Management Module

The SSH session management component provides functions to initiate (Fn pam_sm_open_session ) and terminate (Fn pam_sm_close_session ) sessions. The Fn pam_sm_open_session function starts an SSH agent, passing it any private keys it decrypted during the authentication phase, and sets the environment variables the agent specifies. The Fn pam_sm_close_session function kills the previously started SSH agent by sending it a SIGTERM

The following options may be passed to the session management module:

debug

syslog(3) debugging information at LOG_DEBUG level.

FILES

$HOME/.ssh/identity

SSH1/OpenSSH RSA key

$HOME/.ssh/id_dsa

OpenSSH DSA key

$HOME/.ssh2/id_rsa_*

SSH2 RSA keys

$HOME/.ssh2/id_dsa_*

SSH2 DSA keys

/var/run/pam_ssh/<user>*

ssh-agent environment information. The files are owned by the superuser but readable by the users. The location is Fedora specific, in the original package these files are in $HOME/.ssh/agent-*

AUTHORS

An -nosplit An Andrew J. Korty Aq ajk [at] iu.edu wrote . An Dag-Erling Smorgrav wrote the original OpenPAM support code. An Mark R V Murray wrote the original version of this manual page.