man pf.conf жжот

$man pf.conf
...
pass  out proto tcp from any os OpenBSD keep state
block out proto tcp from any os Doors
block out proto tcp from any os "Doors PT"
block out proto tcp from any os "Doors PT SP3"
block out from any os "unknown"
pass on lo0 proto tcp from any os "OpenBSD 3.3 lo0" keep state
...

Doors, Doors PT SP3 ;)))

PS: Навеяно http://www.linux.org.ru/jump-message.jsp?msgid=1159913