Maiko, I think you are chasing a red herring. It is true that the RIP broadcasts have no checksum, but that is unlikely to be the cause of any problem you may have. Checksums are optional in UDP, these packets don't have them (I can confirm that in a trace on my gateway), but that is not a reason not to process them. It could be argued that it would be better to send the packets with checksum, which could be accomplished using the |SO_NO_CHECK socket option. Rob |