The Book of PF by Peter N.M. Hansteen.

The Book of PF by Peter N.M. Hansteen.

Book blurb: The Book of PF is a practical, how-to guide to building the
network you need with the powerful BSD Packet Filter, PF. From simple
NAT to load balancing, queues, and more, there's something for every BSD
admin.

http://www.nostarch.com/pf.htm

This book has now been printed and is in transit or already arrived at
your favorite computer book store.

We would also like to announce it's availablity on the OpenBSD website,
where part of the proceeds goes to help support the project:

http://www.openbsd.org/orders.html