The Netherlands TCP Wrapper is a very portable public domain tool used to monitor and control remote network services on UNIX systems. Using TCP Wrapper does not impact legitimate computer users or impose a great maintenance burden a system administrator. In fact, if you would like CCD to monitor the TCP Wrapper logs for you, we will. CCD is now using this tool on all of it's UNIX workstations to shield off systems and monitor remote access into the CCD sub domain.
Finger is a good example of an unrestricted network service.
Crackers use this information to establish usage patterns, so they can plan to crack your system when no one is logged on. Access to this type of service can in most cases be drasticly reduced to only allow access from hosts within the .bnl.gov domain. If tftp is used, it should be restricted to BNL access only, there are currently very few good reasons to provide this service to workstations physically outside our gates. The tftp service is normally used for downloading system software to diskless workstations or X terminals, but if configured incorrectly will provide read access to every file on a computer, including the password file. The computer security experts at CIAC obviously know where to look and how to exploit cracks in computer systems, but the interesting point is that the software tools they used for the break-ins are not only publicly available, but free for the taking on the Internet.