bionic (8) pam_otpw.8.gz

NAME

       pam_otpw - verify one-time passwords

SYNOPSIS

       pam_otpw [ arguments ]

DESCRIPTION

       OTPW  is a one-time password authentication system. It compares entered passwords with hash values stored
       in the user's home directory in the file ~/.otpw.  Once a password was entered correctly, its hash  value
       in ~/.otpw will be overwritten with hyphens, which disables its use in future authentication. A lock file
       ~/.otpw.lock prevents that the same password challenge is issued  on  several  concurrent  authentication
       sessions.  This  helps  to  prevent  an  eavesdropper  from  copying a one-time password as it is entered
       instantly into a second session, in the hope to get access by sending the final newline character  faster
       than the user could.

       Both  an  authentication  management  and  a  session management function are offered by this module. The
       authentication function asks for and verifies one-time passwords. The session function prints  a  message
       after login that reminds the user of the remaining number of one-time passwords.

ARGUMENTS

       debug  Turn on debugging via syslog(3).

       nolock Disable  locking.  This  option  tells  the  authentication  function of pam_otpw.so to ignore any
              existing ~/.otpw.lock lock file and not to generate any. With this option, pam_otpw.so will  never
              ask for several passwords simultaneously.

PSEUDO-USER INSTALLATION

       If  a  system  pseudo  user  “otpw” exists in the user database (with UID < 1000), then the password hash
       files will not be stored in the user's home directory. Instead of looking for ~john/.otpw.lock  the  file
       has  to  be  located  in  the home directory of the pseudo user “otpw”, and be named after the user (e.g.
       “/var/lib/otpw/john”). It will be accessed with the effective UID and GID of that pseudo user.

AUTHOR

       The OTPW package, which includes the otpw-gen progam, has been developed by Markus Kuhn. The most  recent
       version is available from <http://www.cl.cam.ac.uk/~mgk25/otpw.html>.

SEE ALSO

       otpw-gen(1), pam(8)

                                                   2014-08-07                                         PAMOTPW(8)