FreeBSD 7.0 manual page repository

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pam_ssh - authentication and session management with SSH private keys



      pam_ssh - authentication and session management with SSH private keys


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


      The SSH authentication service module for PAM, pam_ssh provides function‐
      ality for two PAM categories: authentication and session management.  In
      terms of the module-type parameter, they are the “auth” and “session”
    SSH Authentication Module
      The SSH authentication component provides a function to verify the iden‐
      tity 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:
      use_first_pass  If the authentication module is not the first in the
                      stack, and a previous module obtained the user’s pass‐
                      word, 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          Normally, keys with no passphrase are ignored for authen‐
                      tication purposes.  If this option is set, keys with no
                      passphrase will be taken into consideration, allowing the
                      user to log in with a blank password.
    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:
      want_agent  Start an agent even if no keys were decrypted during the
                  authentication phase.


      $HOME/.ssh/identity  SSH1 RSA key
      $HOME/.ssh/id_rsa    SSH2 RSA key
      $HOME/.ssh/id_dsa    SSH2 DSA key
      ssh-agent(1), pam.conf(5), pam(8)


      The pam_ssh module was originally written by Andrew J. Korty
      〈〉.  The current implementation was developed for the FreeBSD
      Project by ThinkSec AS and NAI Labs, the Security Research Division of
      Network Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
      (“CBOSS”), as part of the DARPA CHATS research program.  This manual page
      was written by Mark R V Murray 〈〉.


Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.