  listfile_mod is a exec modules for Cleo batch system. It controls
PAM module listfile to restrict direct users access to compute nodes.

  Before task start it creates (or updates) files named /DIR/NODENAME
where DIR is predefined dir (must be accessible to all nodes) and
NODENAME is name of used node. If task uses N nodes, there will be
N files created (updated).
  Each created or updated file will contain user name, so user will be
allowed to use services on node.
  After task finish username will be erased from file.

  NOTE! If one user runs 2 or more tasks on onw node, his name will be
erased from file on FIRST task end.

  To enable PAM control for ssh, add theese lines to BEGIN of /etc/pam.d/sshd:

account sufficient pam_listfile.so onerr=succeed sense=allow item=user file=/DIR/root
account required   pam_listfile.so onerr=succeed sense=allow item=user file=/DIR/NODENAME

  DIR and NODENAME were spoken about before.

  In file /DIR/root you may list users, which are always allowed. If you want to
be more restricted, change onerr=succeed in second line to onerr=fail.

