2011-03-20 20:27:04 by chort
Many security practitioners are familiar with Fail2ban, an application that scans log files for various types of suspicious failures and bans the source IP after too many attempts. Most users implement it to protect their Linux systems (via Netfilter/iptables and TCP wrappers), but it also includes methods for Sendmail and IPFW (FreeBSD and OSX).
What is notably missing from the above list is the wildly popular PF (Packet Filter). It was originally designed by Daniel Hartmeier to replace IPF in OpenBSD, but has since been adopted by FreeBSD, NetBSD, and DragonflyBSD. PF is widely embraced due to the simplicity and clarity of the syntax, and the comprehensive array of professional-grade features available.
Ironically, PF is probably better known now due to FreeBSD than the originating project, OpenBSD. It's somewhat startling that no one has yet included PF support in Fail2ban. It's also disappointing that Apple hasn't switch from IPFW to PF as their packet filtering firewall (hint hint).
In the spirit of the Open Source "submit a patch or GTFO" mentality, here's how you can use Fail2ban to insert rules into your PF firewall.
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