david-hoze

This is a reconstruction of http://www.roman10.net/2011/11/27/how-to-calculate-iptcpudp-checksumpart-2-implementation/ The site is gone so I took it from the archive for the sake of C Programming TCP Checksum's answer Enjoy! All credits go to https://github.com/roman10.

This is a follow up of the previous post, how to calculate IP/TCP/UDP checksum part 1 — theory.

IP Header Checksum Calculation Implementation

To calculate the IP checksum, one can use the code below,

2opremio

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <err.h>

#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>