Reauth is a program that performs a klog, sleeps for a period, then
repeats this action indefinitely -- there's nothing particularly
sophisticated about reauth's functionality, and it is only as secure as
the root password of the host machine on which reauth runs.
One can implement reauth's scheme in a variety of ways, but the long and
short of the security issue is that perpetually authenticated AFS hosts
require a secret root password, limited user access and physical
security. This accomplished, unix "server" machines, like mail and
print spoolers, can run with authenticated daemons by using reauth, by
continuously authenticating a system process via crontab entries, or by
placing server IP number acls on the AFS directories that server daemons
need access to. But regardless of the authentication method used, one
must treat server machines with special regard, as UNIX root access
makes them vulnerable to AFS security breaches.
Bob Dew
National Institues of Health
