IPTables unknown option '--dport'

[Ryutatsu]

Title pretty much says it all. I try the line:

sudo iptables -I INPUT 1 --dport 80 -j ACCEPT

and get the error listed in the title.

EDIT: Fixed. I forgot that you have to list a protocol in order to use port. Changing line to:

sudo iptables -I INPUT 1 -p tcp --dport 80 -j ACCEPT

worked