- Lab
-
Libraries: If you want this lab, consider one of these libraries.
- Cloud
- Security

Blocking and Allowing Traffic with a Firewall
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.

Lab Info
Table of Contents
-
Challenge
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.
-
Challenge
Run the Bash Script
- After running your Bash script, run
sudo iptables -L
again. - 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
About the author
Real skill practice before real-world application
Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.
Learn by doing
Engage hands-on with the tools and technologies you’re learning. You pick the skill, we provide the credentials and environment.
Follow your guide
All labs have detailed instructions and objectives, guiding you through the learning process and ensuring you understand every step.
Turn time into mastery
On average, you retain 75% more of your learning if you take time to practice. Hands-on labs set you up for success to make those skills stick.