Porting the PF stateful packet filter
The upcoming release of OpenBSD 3.3 on May 1'st will include, among many other improvements, a notably enhanced version of PF, OpenBSD's stateful packet filter. Some of the more significant enhancements to PF include: 'queues', allowing for per-rule bandwidth control [story]; 'pool options', allowing one to utilize multiple uplinks and to intelligently redirect traffic to multiple servers; 'anchors', which allow one to divide packet filtering rule lists into logical pieces; 'tables', efficiently allowing for very large lists; and other parser improvements that make an already friendly syntax more human readable.
PF replaced its predecessor, IPF, with the release of OpenBSD 3.0 in December of 2001. Since that time, this impressive and relatively new packet filter has grown a faithful following (myself included), and continues to evolve rapidly with each new OpenBSD release. Perhaps the greatest compliment, developers have begun to port PF to other operating systems. Back in January, Joel Wilsson announced his effort to port PF to NetBSD. And more recently, Pyun YongHyeon announced his port for FreeBSD.
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