Packet Sniffing using Raw Sockets in Linux in C

Question

I need to write packet sniffer in Linux that detect http packet that send and save the url that request . I see code in security-freak

and run related code . This code run and only sniff received packet but I need send packet to sniff . In this code how to detect sent packet ?

I can't use any library like libcap or ... (forbidden)
the code is :sniffer.c

Answer 1

With appropriate libpcap or DNET usage You should be able to get all network traffic on the desired layer (protocol - 5) (also this outgoing). But You should know that already.

You need to go through the above libraries manuals and find the appropriate filtering.

Answer 2

Why can't you use any library? Homework?

It's hard to answer without having examples from your code, for example how you set sll_pkttype.

The urlsnarf tool in the dnsiff suite could be worth a look.

Answer 3

You should be using ETH_P_ALL instead of ETH_P_IP as the protocol. ETH_P_IP only listens for incoming IP packets.