Hi Nitin, I know that u r trying to implement a firewall so I guess u r the best person to ask this ? to. How have u gotten around reading the headers and classifying them accordingly. I know that we have the 8 bit L3-proto after the L2-Source Address. However I have been unable to read the proto byte successfully. I will really appreciate it if you could gimme some pointers on this. Regards, Tabrez __________________________________ Do you Yahoo!? Yahoo! Mail - Helps protect you from nasty viruses. http://promotions.yahoo.com/new_mail