Changes

Usually when setting policy rules with iptables, a general "overall" policy is set (default policy chain), and then set policy rules in other chains which act as exceptions to the default policy. Usually, a general policy would apply to ALL types of packets (tcp, udp, icmp) and all communication port numbers (80, 22, etc). The option <b><code><span style="pointer-events: none;cursor: default;color:#3366CC;font-size:1.5em;">-P</span></code></b> is used with the iptables command to set a default policy chain.