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A Cloud Guru

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.

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Path Info

Level

Beginner

Duration

1h 0m

Published

Nov 14, 2018

Challenge

Create a Bash Script
Add four iptables rules that modify Chain INPUT in your Bash script:
1. Flush the current iptables rules.
2. Create a rule that accepts already established connections and any related packets.
3. Create a rule that accepts all SSH traffic.
4. Change the policy of Chain INPUT to drop all incoming traffic.
Challenge

Run the Bash Script
1. After running your Bash script, run sudo iptables -L again.
2. 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.)

Author

A Cloud Guru

The Cloud Content team comprises subject matter experts hyper focused on services offered by the leading cloud vendors (AWS, GCP, and Azure), as well as cloud-related technologies such as Linux and DevOps. The team is thrilled to share their knowledge to help you build modern tech solutions from the ground up, secure and optimize your environments, and so much more!

What's a lab?

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.