Week 7: Iptables Firewall Configuration

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INTRODUCTION

This week there was a need to setup and manipulate the iptables. One of the first steps before starting is to disable the firewall as seen in image 1.



INSTALL

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As in all weeks prior must install iptables and firewall system config tool. This can be completed by using the following commands for iptables #yum -y install iptables-services and #rpm -q iptables. Next, firewall tool use #yum -y install system-config-firewall command. After which need to setup and restart the system. Lastly check the status to ensure it is active. See image 2.

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MANIPULATE IPTABLE

Once this is installed and status is confirmed can manipulate the table to decide access and security settings. Such as disabling telnet connections. One such command is to remove/delete certain lines. First lets check what the iptables currently appear using the command line #iptables --line-numbers -n -L in image 3.

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Next can use #iptables -D INPUT 4 command where the -D (delete) removes the 4th line changes can be seen in image 4.
Some other basic commands include the following:
-F : Deleting (flushing) all the rules.
-X : Delete chain.
-t table_name : Select table (called nat or mangle) and delete/flush rules.
-P : Set the default policy (such as DROP, REJECT, or ACCEPT).


CONCLUSION
It is important to have a good firewall setup to increase security and this is done through iptables on Linux. Above is just some basics but it puts a person on the right path to computer security.