Flush the rules of the specified chain, or for all chains if no chain is specified. Zero the datagram and byte counters for all rules of the specified chain, or for all chains if no chain is specified. A chain of the same name must not already exist. This is how user-defined chains are created. For this command to be successful, there must be no references to the specified chain from any other rules chain.
DROP causes the datagram to be discarded.
There are a number of iptables parameters that constitute a rule specification. Wherever a rule specification is required, each of these parameters must be supplied or their default will be assumed. Valid protocol names are tcp , udp , icmp , or a number, if you know the IP protocol number. If this parameter isn't supplied, it will default to match all protocols. The address may be supplied as a hostname, a network name, or an IP address.