In /afs/sipb/project/sipb-athena/src/login/Linux/athena.c
We define _PATH_NOCREATE as /etc/nocreate" and _PATH_NOREMOTE as
  /etc/noremote.

  NOCREATE first checked in athena_login (called from login.c)
    If it is not able to find you in /etc/passwd, it checks for
    existence of NOCREATE ---
    if the file exists then you are not allowed to login, we return FALSE,
    and set an error flag.
    (Additionally, if you are a remote user and NOREMOTE exists, you are
    denied access again)

  NOCREATE also checked in make_homedir
    If the file exists, we exit the procedure with -1.

  NOCREATE also checked in get_groups
    If the file exists, we return. No specific value returned.