Linux Kernel Security

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Security

Linux Kernel Security

Many important security configurations can be set using kernel parameters. In this hands-on lab, we will learn how to find and modify these parameters using various utilities. These skills are essential for passing advanced security certification exams such as the LPIC 303-200 exam.

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Lab Info

Level

Advanced

Last updated

Sep 09, 2025

Duration

30m

Challenge

Create a Text File for the Kernel Parameters
1. Run the following command:
```
touch /home/cloud_user/investigate.txt
```
Challenge

Install the Kernel Documentation
1. Run the following command:
```
sudo yum install kernel-doc
```
Challenge

Find and Document the Value of the `randomize_va_space` Parameter
1. View the value of the randomize_va_space parameter by running the following command:
```
sysctl -ar randomize_va
```
1. Add the value to the investigate.txt file.
```
sysctl -ar randomize_va >> investigate.txt
```
Challenge

Find and Document the Values of All ICMP Kernel Parameters
1. Run the following command:
```
sysctl –ar icmp >> investigate.txt
```
Challenge

Temporarily Disable ICMP Using a Kernel Parameter
1. Run the following command:
```
sudo sysctl –w net.ipv4.icmp_echo_ignore_all=1
```
Challenge

Find and Document the Current Kernel Security Limits
1. View the contents of /etc/security/limits.conf.
```
vim /etc/security/limits.conf
```
1. Write the contents of /etc/security/limits.conf to investigate.txt.
```
cat /etc/security/limits.conf >> investigate.txt
```
1. Locate the current security limits for cloud_user.
```
ulimit -a
```
1. Write the output of the ulimit -a command to investigate.txt.
```
ulimit -a >> investigate.txt
```

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