IPtables and firewall

        Firewall [Iptables]

- Works on port no 65535
- It is reponsible for Filtering
  Filtering is of two types :
i.     Packet Filtering    [Using IP ex = 192.168.0.0]
ii.    Content Filtering    [Using word ex= "chat","job" etc]

Packet Filtering : It contain 3 chains

a.)  Input Chain : It contains all the data coming from outside the world for the system
b.)  Output Chain: The data which is been sent by system itself is put in output chain
c.) Forward Chain: The data which is routed by system for others is put in this chain

IPtables takes the following reactions :

a.) Accept     : Acknowledgement sent to sender
b.) Reject    : Error sent to sender
c.) Drop     : No Acknowledgement/No Error


 How to configure iptables using GUI

# yum install iptables
# service iptables status/start/stop/restart/save
# chkconf iptables on

To List iptables Rules :
# iptables -L

To Flush Iptable :
# iptables -F
now, save the changes
# service iptables save

To view information :
# info iptables