> For the complete documentation index, see [llms.txt](https://fashaun.gitbook.io/linux-iptables/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://fashaun.gitbook.io/linux-iptables/chapter1.md).

# iptables

## Table

* nat
* mangle - For the modification of packets, ex:time to live (TTL), type of service (TOS)
* filter

## Chain

* INPUT
* OUTPUT
* FORWARD
* PREROUTE
* POSTROUTE

## TARGET

* ACCEPT
* DROP
* REJECT
* QUEUE

## Policy

If all rules are not match, then go to default policy.

iptables-save \*filter :Chain -rule

### conntrack tool

It is the ability to maintain connection information in memory.

* conntrack Command 
  * table name: conntrack / expect
    * Parameters:
      * -L $table

        List all conntrack in table
      * -D $table 

        Delte all conntrack in table
      * -F $table

        Flush all conntrack in table
    * Options:
      * -p $protocol

        ex: tcp, udp