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Labs

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.

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Labs

Path Info

Rating
(11 reviews)
Level
Clock icon Beginner
Duration
Clock icon 1h 10m
Published
Clock icon Oct 22, 2024

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Table of Contents

  1. 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!

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

Craig is a former Marine that has over a decade of IT experience, mainly focusing on Palo Alto Firewalls and Cisco Routers and Switches, and has certifications from both vendors. When not working, Craig enjoys spending time with his family.

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.

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.