Modifying Kernel Parameters

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Modifying Kernel Parameters

The Linux kernel provides a wide array of parameters that can alter how the system behaves. In this lab, you will be tasked with modifying specific parameters for the current session and ensuring that these changes will persist through a reboot.

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Lab Info

Level

Intermediate

Last updated

Apr 06, 2025

Duration

30m

Challenge

Modify the Swappiness Parameter to Equal 10 for the Current Session

Use sysctl to change the swappiness value to 10:

sysctl -w vm.swappiness=10
Challenge

Ensure That the Changes Made to the Swappiness Parameter Will Persist through a Reboot

Create a file in /etc/sysctl.d/ called 60-swap.conf with the following contents:

vm.swappiness = 10

This can be done with a text editor or through the command line:

echo "vm.swappiness = 10" > /etc/sysctl.d/60-swap.conf
Challenge

Disable icmp_echo_ignore_all and Enable icmp_echo_ignore_broadcast for the Current Session

Disable icmp_echo_ignore_all using the sysctl command:

sysctl -w net.ipv4.icmp_echo_ignore_all=0

Enable icmp_echo_ignore_broadcast using the sysctl command:

sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=1
Challenge

Ensure That the Changes Made to icmp_echo_ignore_all and icmp_echo_ignore_broadcast Persist through a Reboot
Create a file in /etc/sysctl.d/ called 60-icmp.conf with the following system variables:
```
icmp_echo_ignore_all = 0
icmp_echo_ignore_broadcasts = 1
```
This can be done with a text editor or from the command line using the echo command:

echo -e 'icmp_echo_ignore_all = 0\nicmp_echo_ignore_broadcasts = 1' > /etc/sysctl.d/60-icmp.conf
Challenge

Enable ip_forward for the Current Session

Enable ip_forward using the sysctl command:

sysctl -w net.ipv4.ip_forward=1
Challenge

Ensure That the Changes Made to ip_forward will Persist through a Reboot
Create a file in /etc/sysctl.d/ called 60-ip.conf with the following text:
```
net.ipv4.ip_forward = 1
```
This can be done with a text editor or from the command line:

echo "net.ipv4.ip_forward = 1" > /etc/sysctl.d/60-ip.conf

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