The policy ACCEPT allows connections the policy REJECT refuses connections returning an error the policy DROP refuses connections without producing errors. There are 3 types of policies: ACCEPT, REJECT and DROP. The output also shows there are no defined rules, and all defined policies are accepted. Where INPUT refers to policies regarding incoming traffic, OUTPUT refers to policies applied to outgoing traffic, and FORWARD refers to routing policies. The output above shows 3 rows: Chain INPUT, Chain FORWARD, and Chain OUTPUT. The following list shows what chains include each table: Each table contains built-in (rule) chains. For example, there is a table for routing tasks and another table for filtering tasks each table contains rule chains.Īvailable tables are filter, nat, raw, security, and mangle. TABLE: Tables are iptables features for each purpose. TARGET: When using iptables, a target is an action you want Iptables to apply when a packet matches a rule.ĬHAIN: A chain is a list of rules available built-in chains are: INPUT, OUTPUT, FORWARD, PREROUTING, and POSTROUTING. Note: sudo command was added for readers who need to copy-paste the rules mentioned in this iptables tutorial. With Iptables, users can accept, refuse, or onward connections it is incredibly versatile and widely used despite being replaced by nftables.Īfter reading this tutorial, you will understand Iptables policies and define Iptables rules to protect your home network.

Iptables is a command-line firewall that filters packets according to the defined rules.

Iptables examples