Prepocessing in ipfw

[Dan Nelson]

In the last episode (Jul 14), Matin Tamizi said:
> How can I use the preprocessing feature in ipfw to run incoming
> packets through my own C program?  How can my C program communicate
> to ipfw to drop (deny) and packet or connection?

If you're talking about the -p flag to ipfw, that's just for parsing
config files (like what cpp does with #include and #define for C).

Take a look at divert sockets for a way to capture packets from ipfw
into a program, and then reinject (or drop) them.  See the divert and
ipfw manpages.  natd uses divert sockets, so you can look at its source
to see how they work.

-- 
	Dan Nelson
	dnelson at allantgroup.com