When playing with iptables, you might encouter this message:
iptables v1.4.7: unknown option `--sport'
Try `iptables -h' or 'iptables --help' for more information.
This is because you have used the "--sport" option without having specified which protocol it applies to. You have to tell wether you want to apply this on TCP or UDP.
The behaviour of iptables is not to assume you want to apply this to both.