Am I secure ??

How To Start iptables

You can start, stop, and restart iptables after booting by using the commands:

[root@bigboy tmp]# service iptables start
[root@bigboy tmp]# service iptables stop
[root@bigboy tmp]# service iptables restart

To get iptables configured to start at boot, use the chkconfig command:

[root@bigboy tmp]# chkconfig iptables on


Determining The Status of iptables
You can determine whether iptables is running or not via the service iptables status command. Fedora Core will give a simple status message. For example

[root@bigboy tmp]# service iptables status
Firewall is stopped.
[root@bigboy tmp]#

Packet Processing In iptables

All packets inspected by iptables pass through a sequence of built-in tables (queues) for processing. Each of these queues is dedicated to a particular type of packet activity and is controlled by an associated packet transformation/filtering chain.

There are three tables in total. The first is the mangle table which is responsible for the alteration of quality of service bits in the TCP header. This is hardly used in a home or SOHO environment.

The second table is the filter queue which is responsible for packet filtering. It has three built-in chains in which you can place your firewall policy rules. These are the:

* Forward chain: Filters packets to servers protected by the firewall.
* Input chain: Filters packets destined for the firewall.
* Output chain: Filters packets originating from the firewall.

The third table is the nat queue which is responsible for network address translation. It has two built-in chains; these are:

* Pre-routing chain: NATs packets when the destination address of the packet needs to be changed.
* Post-routing chain: NATs packets when the source address of the packet needs to be changed

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