Re: Stateless dropping of packets

[Kevin Buhr <buhr@telus.net>]

Florian Weimer <fw@deneb.enyo.de> writes:
> 
> Is this extremely important application of the PREROUTING chain
> documented somewhere?  Should I feel embarrassed? 8-)

No, I haven't seen it documented explicitly.  It's just a fortunate
side effect of the fact that the DROP target can be used anywhere and
there's a fairly general-purpose table ("mangle") that has a
PREROUTING chain.

There's no particular reason for the "filter" table *not* to implement
PREROUTING and POSTROUTING chains (at least not that I can see) except
for a very small performance hit.  I guess no one thought there'd be
much of a use for them.  And it would break the nice rule of thumb
that a packet only passes through one of the three chains of the
"filter" table (not counting packets throught the loopback interface
which pass through OUTPUT then back through INPUT).

-- 
Kevin <buhr@telus.net>