A hostname is a human-readable name assigned to a computer or device connected to a network. It serves as a unique identifier, similar to a person’s name, making it easier to recognize and manage a device on a network.

Changing the hostname in Linux can be done using different commands and configuration files, depending on your Linux distribution. Here are methods for some of the commonly used distributions:

Method 1: Using the hostname Command

You can use the hostname command to change the system hostname temporarily. However, the change will not persist after a reboot.

sudo hostname new-hostname

A temporary hostname change is necessary when:

• Simulating different network environments: You might change the hostname to mimic different servers or devices during testing, allowing you to observe how software or network configurations behave under various scenarios.

• Troubleshooting network issues: Temporarily changing the hostname can help isolate problems related to hostname resolution or configuration.

• Testing software compatibility: Some software might have dependencies on specific hostnames. You can change the hostname to test how the software reacts.

• Running multiple services on a single machine: If you’re hosting multiple services that rely on hostname-based configuration, you might temporarily change the hostname to isolate them from each other for testing or debugging.

• Preventing conflicts: Changing the hostname can temporarily prevent conflicts between services that expect different hostnames.

Method 2: Editing the /etc/hostname File

If you want to make the hostname change permanent in Linux, you need to edit the /etc/hostname file:

sudo nano /etc/hostname

Replace the existing hostname with your new hostname and save the changes.

For the new changes to take effect, you will need to restart the networking service by running one of the following commands based on your system;

• For Linux systems using init, use this command to restart the networking service

sudo service networking restart

• For Linux systems that use systemd, the following command is recommended:

systemctl restart systemd-hostnamed.service

Method 3: Editing the /etc/sysconfig/network File

For distributions like CentOS and RHEL, you can edit the /etc/sysconfig/network file.

sudo nano /etc/sysconfig/network

Change the HOSTNAME value to your new hostname and save the file.

Method 4: Using the hostnamectl Command

On systems using systemd, such as recent versions of Ubuntu, Fedora, and others, you can use the hostnamectl command. Here is the command to use:

sudo hostnamectl set-hostname new-hostname

Regardless of the method you choose, it’s important to note that changing the hostname may affect certain services and configurations that rely on the hostname. You can confirm if the new hostname is working by running the following command on the system terminal

hostname

Running the above command will display the Linux system hostname on the terminal.

It’s also a good practice to reboot the entire system to ensure that the overall changes take effect. Here is the command to use to reboot Ubuntu Linux:

sudo reboot

When do you need to change a hostname on Linux?

Here are scenarios where changing the hostname on Linux is a strict prerequisite:

Network Identity

Each device on a network needs a unique hostname to differentiate itself. If multiple devices have the same hostname, it can cause communication errors, routing problems, and access conflicts. Changing hostnames ensures distinct identities.

Domain Name Server (DNS) Configuration

When setting up DNS for a network, each hostname is associated with an IP address. Conflicting hostnames can disrupt DNS resolution, leading to websites and services being inaccessible.

Network Management Tools

Tools like network monitoring, intrusion detection, and asset management rely on accurate hostnames to identify and track devices effectively. Conflicts can hinder their functionality.

Security and Compliance

Some security policies mandate unique hostnames for each device to track activity and identify potential threats. This aids in incident response and vulnerability management.

Certain industry regulations or organizational guidelines may require specific hostname formats or naming conventions for auditing and tracking purposes.

System Administration and Management

Descriptive hostnames can improve system administration by conveying device roles or functions (e.g., “webserver1”, “database2”). This makes it easier to manage and troubleshoot complex environments.

In virtualized environments, each virtual machine or container typically has its own hostname for proper identification and management within the virtual infrastructure.

License Management

Some software licenses are tied to specific hostnames, and changing the hostname may be necessary for proper activation and compliance.

Certain applications rely on hostnames for configuration, communication, or logging purposes. A change may be required to ensure correct functionality.

Hostname-Based Service Configuration

Hostnames are often used in web server configuration to define virtual hosts or specify server names for SSL/TLS certificates.

Hostnames play a crucial role in email server configuration for identifying the sending and receiving domains.

Services like FTP, databases, and file sharing may also require hostname-based configuration for domain name resolution or authentication.