Actions

-F – flush – deletes all the rules in the specified chain, e.g., iptables -t nat -F POSTROUTING
-Z – zero counters – sets all the packet and byte counters to zero in the specified chain or ALL chains if none is specified, e.g., iptables -Z FORWARD
-N – new chain – create a new user-defined chain with the given name, e.g., iptables -N NexusUsers

-F – flush – deletes all the rules in the specified chain, e.g., iptables -t nat -F POSTROUTING