Hello, I am facing a strange problem while trying to create IP packets through a kernel module . iph = skb->nh.iph I set iph->check = 0 and then iph->check = ip_fast_csum (iph, iph->ihl) If I do the checksum again, it returns a non zero value. This happens on a RH6.0 machine, on which I have kernel 2.4.2 installed. The same piece of code runs unaltered on another RH7.1 machine with kernel 2.4.2, and on several other machines with other configurations. What could be the problem? data alignment? (but then why does it work on some (same architecture) machines and not others?) Something to do with gcc? TIA akshay __________________________________________________ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail http://personal.mail.yahoo.com/ - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org