Identity of users. Any person connecting to the CS network must be identifiable. For example, every piece of e-mail sent from a departmental account is sent with an automatically generated header that contains the name of the sender. Logs are always generated. Systems administrators regularly review the logs.
System administrators watch for probes, and, when one is detected, they immediately respond.
System and service software is continually upgraded. Critical systems are backed up. Systems administrators filter for well-known vulnerabilities at the router. To balance the sometimes competing needs for security and flexibility, the department supports two networks. The first, a Unix-based production network, is strictly controlled and closely watched.