OpenBSD's stateful packet filter, PF, offers an amazing feature set and support across the major BSD platforms. Like most firewall software though, unlocking PF's full potential takes a good teacher. Peter . Hansteen's PF website and conference tutorials have helped thousands of users build the networks they need using PF. The Book of PF is the product of Hansteen's knowledge and experience, teaching good practices as well as bare facts and software options. Throughout the book, Hansteen emphasizes the importance of staying in control by having a written network specification, using macros to make rule sets more readable, and performing
