Linux+ Security: Harden Linux Systems
In this lab, you’ll practice restricting the ports and IPs the server is listening on, removing unneeded services, securing ICMP, and brute force password attacks. When you’re finished, you’ll have the fundamental skills to harden a Linux system.
Terms and conditions apply.
Challenge
Get Started in the Lab Environment
Here are the initial instructions and explanation of the lab environment. Read this while your environment is busy creating itself from nothing. Yes, this violates physics; we know. How fun!
Challenge
Check Listening Ports and Restricting Access
To start this lab, you will check which ports the Linux server is listening on. From there, you will learn how to restrict each port to specific IP families as well as determine, if applicable, which IP addresses on the Linux host should be listening for each port.
Challenge
Remove Unneeded Services
Now that the ports have been locked down for the services you want on this server, it’s a best practice to remove unnecessary services that won’t be used by the server.
Challenge
Secure ICMP Access Using sysctl
ICMP is commonly used to verify that systems are functioning, but that can be a security risk. You will learn how to restrict the server's response to ICMP, or allow it to respond but limit the access
Challenge
Lock Upon Failed Login Attempts
By default, Linux will not lock out a user if they continue to enter the wrong password, which could allow brute force attacks. This challenge will show you how to configure the server to lock out a user for an extended period of time.
Challenge
The Last Challenge
Welcome to the final challenge! This is your last chance to experiment in the environment. Clicking Finish Lab will end this little world that flittered into existence just for you.
Provided environment for hands-on practice
We will provide the credentials and environment necessary for you to practice right within your browser.
Guided walkthrough
Follow along with the author’s guided walkthrough and build something new in your provided environment!
Did you know?
On average, you retain 75% more of your learning if you get time for practice.
Recommended prerequisites
- Comfortable in a Linux CLI environment
- Able to use vim
- Knowledge of networking, such as IPs, ports, sockets, and ICMP