Thanks for all the help... as I said, I solved the problem by using the incremental checksum method described in rfc1624, haven't looked through the ip_nat_dumb code, but, I think using incremental checksums would be faster than doing the checksumming all over again... --- - Amit http://amitshah.nav.to/ amitshah@gmx.net -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ IRC Channel: irc.openprojects.net / #kernelnewbies Web Page: http://www.kernelnewbies.org/