[$] Faster firewalls with bpfilter

From
servers in a data center to desktop computers, many devices
communicating on a network will eventually have to filter network
traffic, whether it's for security or performance reasons. As a result,
this is a domain where a lot of work is put into improving performance:
a tiny performance improvement can have considerable gains.

Bpfilter is a
project that allows for packet filtering to easily be done with BPF, which can
be faster than other mechanisms.