Hygiene: block-policy, scrub og antispoof

block-policy:

drop - droppe uten retur, eller

return - Connection refused, Destination unreachable, osv

set block-policy return

scrub:

normalisering, defragmentering

scrub in all

antispoof:

"Denne pakken skulle ikke vært her"

antispoof for $ext_if
antispoof for $int_if