Interface groups: dynamic expansion


for an interface foo0, used in a rule like "pass to (foo0)", pf creates a table called by the interface within the _pf anchor

<henning@skywalker>  $ echo "pass to (wi0)" | sudo pfctl -f - 
<henning@skywalker>  $ sudo pfctl -a _pf -t wi0 -T show
   172.16.43.1
   fe80::202:6fff:fe37:fc66

create a table named by the group, again inside _pf, and put all member interface's addresses in them
on changes, the addresses need to be updated in the interface _and_ all group tables
additional gotcha: interfaces can leave and join groups any time, that needs handling too