OpenBSD journal has published excellent PF Firewall Ruleset Optimization tutorial.
From the article:
"This is the first installment in a series of three articles about PF. I originally wrote them as chapters for a book, but then publication was cancelled. Luckily, the rights could be salvaged, and now you get to enjoy them as undeadly.org exclusives."
Firewall Ruleset Optimization topics:
- The significance of packet rate
- When pf is the bottleneck
- Filter statefully
- The downside of stateful filtering
- Ruleset evaluation
- Ordering rulesets to maximize skip steps
- Use tables for address lists
- Use quick to abort ruleset evaluation when rules match
- Anchors with conditional evaluation
- Let pfctl do the work for you
- Testing Your Firewall (read)
- Firewall Management (upcoming)
Read more at OpenBSD journal...