packet filter firewall

kikilinux · 03-10-2013, 01:59 PM

hi
i wanna write a simple packet filter firewall in C programming language ,can i write a program by socket programming and direct the traffic to a port which my program listen to it and then in my program i want to separate the header portion of packet from payload to do filtering policy on header portion and accept or drop the packet.
just like a proxy

is that possible ?
if it is , the problem face to that ?
ur suggestions ?

best

NevemTeve · 03-10-2013, 04:13 PM

Packet filtering is performed by the kernel, not by an user program. You can give hints to the kernel though, via program iptables.

unSpawn · 03-10-2013, 04:58 PM

Quote:

You can give hints to the kernel though, via program iptables.

...also see NFQUEUE, a packet handler in userland (with bindings).