Blocking udp flood trafiic using pf, hints welcome

[Elvir Kuric]

Hi all,

I am playing with pf tool on openbsd/freebsd platforms and it is super
tool for firewalls. On thing is interesting for me, and I am hopping
someone has expeience with this.

If I say

block log all
block in log (all) quick on $ext_if proto udp from any to $ext_if

this would block all traffic on $ext_if, but on my ext_if I recive a
lot of ( huge amount ) of udp generated traffic which make me a lot
of problems.
I also tryed to add small pipe and play with ALTQ to handle this but
it did not help a lot. Also I know that every packet which hit my
ext_if should be
 processed ( or least  take a little processor resources, if I block
it with keyword quick ), but I am wondering is there some way to
decrease impact on system
when a lot of packets arive in short time.

My question would be, what are your experinces with battling against
boring udp flooders ? Platform are FreeBSD / OpenBSD and all works
like a charm except time to time, stupid udp flood atacks.

Any suggestion is welcome,

With Regards,

Elvir Kuric