IP tables Simplified.

IPtables in unix are nothing but firewall rules defined for the machines.

There are four types of IPtables.

1. Filter Table(default table)
2. NAT table
3. Mangle table
4. Raw table

To list the iptables you need to type following command.

1) Filter table:
# iptables --list (if you dont specify -t (type) filter tables will be displayed)
or
# iptables -t filter --list

Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

2) To list mangle tables.

# iptables -t mangle --list

3) To list NAT tables.

#iptables -t nat --list

4) To list raw tables.

# iptables -t raw --list

start or stop iptables rules

To start (Enforce) iptable rules:

#Service iptables start

To stop (rollback) iptables rules:

#Service iptables stop

More Information over iptables can be obtained from below link.

http://www.thegeekstuff.com/2011/01/iptables-fundamentals/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+TheGeekStuff+%28The+Geek+Stuff%29