RE: Using Debian packet sockets

["Bender, John" <john.bender@GD-CS.Com>]

I am working on developing some bridge software that takes Ethernet frames
from a PC, filters them, then changes them to UDP packets then sends them to
a server. This process needs to be reversed when UDP packets are returned
from the server destined for that PC.   
I need to use:
     1) Debian Linux v.2.4.13
     2) host system type = i686-pc-linux-gnui
     3) two (2) National Semiconductor PCI Ethernet Interface card

 I need to trap and modify all the IEEE 802.3 frames on one of the
interfaces (/dev/eth1) and send it out the other (/dev/eth0).
How do you trap all traffic?  (i.e. Use a PACKET socket??)  Has anyone done
this before using Debian?  What system calls are necessary to successfully
accept/send raw (IEEE 802.3) frames from/to the NIC device driver?


John Bender
GENERAL DYNAMICS
C4 Systems
Phone: 781-455-2428
John.Bender@GD-CS.com