How to Write iptables Rules for IPv6 - Linux.com

First, see if you already have any rules:

$ sudo ip6tables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination 
 Save
This shows there are no existing rules. If you already have some rules, clear them with this command:

$ sudo ip6tables -F