3.3 Tables

A table in iptables represents a specific kind of network traffic. There are three predefined tables.

• filter: this table specifies what to do with “normal” traffic packets. In other words, if a packet/fragment is not special (as describe in the other two tables), it is processed by chains of this table.
• nat: this table specifies what to do with connection initiation packets.
• mangle: this table specifies what to do with customized packet processing.

Note that a packet can be handled by multiple tables. For example, a packet intended for a host inside a private network can be processed by the filter table first, then processed by the nat table.