PAM_SSH(8)

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, pam_ssh 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 (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.

nullok
    Allow empty passphrases.

  SSH Session Management Module
The SSH session management component provides functions to initiate (pam_sm_open_session()) and terminate (pam_sm_close_session()) sessions. The 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 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

SEE ALSO
ssh-agent(1), syslog(3), pam.conf(5), pam(8)

AUTHORS

-nosplit Andrew J. Korty <ajk@iu.edu> wrote pam_ssh. Dag-Erling Smorgrav wrote the original OpenPAM support code. Mark R V Murray wrote the original version of this manual page.