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PAMOTPW(8)		     System Manager's Manual		      PAMOTPW(8)

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  authen-
     tication.	A  lock  file ~/.otpw.lock prevents that the same password chal-
     lenge is issued on several concurrent authentication sessions.  This  helps
     to  prevent  an  eavesdropper from copying a one-time password as it is en-
     tered 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 of-
     fered 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 sev-
	    eral passwords simultaneously.

PSEUDO-USER INSTALLATION
     If a system pseudo user aotpwa 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  lo-
     cated  in	the home directory of the pseudo user aotpwa, and be named after
     the user (e.g. a/var/lib/otpw/johna). It will be accessed with  the  effec-
     tive 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)

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