Normalization: scrub

Starting with OpenBSD 4.6, scrub is a state option:

set state-defaults pflow
match in all scrub (no-df max-mss 1440)
match in proto tcp from to self tag fortyeight
pass in proto tcp tagged fortyeight scrub (random-id reassemble tcp)
pass proto tcp from self to port 9000 scrub (set-tos lowdelay)

Also min-ttl, random-id, set-tos