Defining The Iptables Rule

• Decide which packets you want filtered.
• Lets filter all ICMP packets coming through the loopback interface:

  • iptables -I INPUT 1 --in-interface lo --proto icmp --jump QUEUE

  (the '-I ... 1' inserts this as the first filtering rule).
• By default, matching packets will be discarded, until we have a program listening for them.

Originally written by guy keren