For the Security+ Exam, it is important to understand how firewall rules work. In this hands-on lab, we will configure a couple of firewall rules on iptables, which is built into CentOS. After completing this lab, you will understand how firewall rules work in a hierarchical manner to allow and block traffic.
Learning Objectives
Successfully complete this lab by achieving the following learning objectives:
- Create a Bash Script
Add four iptables rules that modify Chain INPUT in your Bash script:
- Flush the current iptables rules.
- Create a rule that accepts already established connections and any related packets.
- Create a rule that accepts all SSH traffic.
- Change the policy of Chain INPUT to drop all incoming traffic.
- Run the Bash Script
- After running your Bash script, run
sudo iptables -Lagain. - Compare and contrast the default rules to those you put into place with your Bash script. (You should get a feel for how the policy works to block any traffic not specifically allowed as well as how firewall rules look.)
- After running your Bash script, run
