Tech Tutorial: Manage Basic Networking #

Introduction #

In this tutorial, we will focus on configuring network services to start automatically at boot on a Red Hat Enterprise Linux (RHEL) system. This is a crucial skill for system administrators, particularly for those preparing for the Red Hat Certified System Administrator (RHCSA) exam. Ensuring that network services start automatically enhances the reliability and availability of network-dependent applications and services.

Step-by-Step Guide #

Step 1: Understanding Systemd #

RHEL uses systemd as its init system, which manages the boot process and system services. Systemd introduces the concept of “units” to manage different resources. Services are one type of unit, handled by service files (with the .service extension).

Step 2: Identify the Service #

Before you enable a service to start at boot, you need to know its exact service name. You can list all services to find the one you’re interested in:

systemctl list-units --type=service --all

For our tutorial, let’s assume we want to enable the NetworkManager service, which is crucial for managing network connections.

Step 3: Check the Current Status of the Service #

To check whether the NetworkManager service is currently active and enabled, use:

systemctl status NetworkManager

This command provides detailed information about the service, including its current status, whether it’s enabled, and recent log entries.

Step 4: Enable the Service to Start at Boot #

To ensure the NetworkManager service starts automatically at boot, use the following command:

sudo systemctl enable NetworkManager

This command creates a symbolic link from the system’s systemd service directories to the NetworkManager.service file, which tells systemd to start this service at boot time.

Step 5: Verify the Service is Enabled #

After enabling the service, it’s a good practice to check if it’s correctly set to start at boot:

systemctl is-enabled NetworkManager

This command will return enabled if the service is set to start at boot successfully.

Step 6: Reboot and Check #

To fully verify that everything is set up correctly, reboot the system:

sudo reboot

After the system restarts, check the status of the NetworkManager service again to ensure it’s active:

systemctl status NetworkManager

Detailed Code Examples #

Here’s a detailed breakdown of the commands used in this tutorial:

Listing Services:
```
systemctl list-units --type=service --all
```
Use this command to explore all services available on your system, both active and inactive.
Checking Service Status:
```
systemctl status NetworkManager
```
This command is used to inspect the current state of the NetworkManager service.
Enabling a Service:
```
sudo systemctl enable NetworkManager
```
This command sets the NetworkManager service to start automatically at boot.
Checking if a Service is Enabled:
```
systemctl is-enabled NetworkManager
```
This outputs the enable status of the NetworkManager service.
Rebooting the System:
```
sudo reboot
```
Reboots the system, which is useful for testing that changes persist after a restart.

Conclusion #

In this tutorial, we’ve covered how to configure network services to start automatically at boot on a Red Hat Enterprise Linux system, using NetworkManager as an example. This skill is essential for system administrators to ensure that network configurations are automatically applied and maintained across system reboots, thereby improving system reliability and network availability. By mastering these commands and understanding the principles behind systemd, you will enhance your capabilities as a Linux system administrator and be better prepared for the RHCSA exam.