Association for Computing Machinery
Firewalls are the cornerstones of the security infrastructure for most enterprises. They have been widely deployed for protecting private networks. The quality of the protection provided by a firewall directly depends on the quality of its policy (i.e., configuration). Due to the lack of tools for analyzing firewall policies, many firewalls used today have policy errors. A firewall policy error either creates security holes that will allow malicious traffic to sneak into a private network or blocks legitimate traffic and disrupts normal business processes, which in turn could lead to irreparable, if not tragic, consequences. A major cause of policy errors are policy changes. Firewall policies often need to be changed as networks evolve and new threats emerge.