How to Change Linux Server Name Easily and Safely

Changing the hostname of a Linux server is a common administrative task that can help you better manage your networked machines. The hostname is the identifier your server uses on a network and can be crucial for identification, logging, and configuration purposes.

detailed instructions on how to change the hostname on various Linux distributions, covering both temporary and permanent methods. It also explains the underlying configuration files involved and some best practices.

What is a Hostname?

The hostname of a Linux server is a human-readable label that identifies the device on a network. It is used by various services and applications to refer to the server.

A hostname can be a simple name like server1 or a fully qualified domain name (FQDN) like server1.example.com.

Having a meaningful hostname makes system administration easier, especially when managing multiple servers.

Why Change the Hostname?

There are several reasons why you might want to change the hostname of your Linux server:

• Rebranding: Changing the hostname to align with new company naming conventions.
• Network organization: Ensuring hostnames reflect server roles or locations.
• Cloning or redeployment: Avoiding duplicate names on the network when duplicating servers.
• Correction: Fixing incorrectly set hostnames during installation.

Types of Hostnames

Check Current Hostname

Before making any changes, it’s a good idea to check the current hostname of your system. You can do this with several commands:

hostname
hostnamectl status
cat /etc/hostname

The hostname command returns the current hostname, while hostnamectl status (available on systemd-based Linux) gives more detailed information. The file /etc/hostname typically contains the static hostname.

Changing Hostname Temporarily

You can change the hostname temporarily without editing any files. This change will last until the next reboot.

sudo hostname new-hostname

Replace new-hostname with your desired hostname. This command immediately changes the hostname but does not persist after reboot.

Note: This method does not update configuration files, so a reboot will revert the hostname to the previous static value.

Changing Hostname Permanently

For the hostname change to persist after reboot, you need to update system configuration files. The method varies slightly depending on your Linux distribution and init system.

Method 1: Using hostnamectl (systemd-based systems)

Most modern Linux distributions use systemd, which provides the hostnamectl command to manage hostnames.

sudo hostnamectl set-hostname new-hostname

This command sets the static hostname permanently. It updates the necessary files and informs systemd of the change.

Method 2: Manually Editing Configuration Files

If your system doesn’t use systemd or you prefer manual configuration, you can edit the following files:

Follow these steps:

1. Open /etc/hostname in a text editor with root privileges:

sudo nano /etc/hostname

Replace the existing hostname with your new desired hostname and save the file.

2. Edit /etc/hosts to update any references to the old hostname:

sudo nano /etc/hosts

Look for lines like:

127.0.0.1   old-hostname
::1         old-hostname

Replace old-hostname with your new hostname. Save and exit.

Once these changes are made, reboot your system:

sudo reboot

After reboot, verify the hostname has changed:

hostname

Additional Tips and Best Practices

• Use valid hostnames: Hostnames should only contain letters (a-z), numbers (0-9), and hyphens (-). Avoid spaces and special characters.
• Hostname length: Keep hostnames under 63 characters to comply with DNS standards.
• Update DNS records: After changing your hostname, update any DNS or network configuration to reflect the change.
• Check running services: Some services may cache the hostname or require a restart to pick up the new hostname.
• Remote connections: If connected via SSH, updating hostname on the remote server won’t affect your session but might appear on your terminal prompt depending on your shell config.

Hostname in Network Configuration

Some Linux distributions or network managers may override your hostname based on DHCP or other network configurations.

Make sure to check these if your hostname keeps reverting or is not persistent.

Changing Hostname on Popular Linux Distributions

Ubuntu / Debian

Ubuntu and Debian systems use systemd on recent releases and support hostnamectl.

sudo hostnamectl set-hostname new-hostname

Alternatively, edit /etc/hostname and /etc/hosts manually. After changes, reboot or restart the hostname service:

sudo systemctl restart systemd-logind.service

CentOS / RHEL / Fedora

These distributions also support hostnamectl. Use the same command to set the hostname:

sudo hostnamectl set-hostname new-hostname

Edit /etc/hosts as needed. To verify, use:

hostnamectl status

Arch Linux

Arch Linux uses systemd as well. Set the hostname using:

sudo hostnamectl set-hostname new-hostname

Edit /etc/hosts and /etc/hostname if manual adjustments are preferred.

Verify Hostname Change

After changing your hostname, verify it with following commands:

Troubleshooting Hostname Issues

If hostname changes do not take effect as expected, consider the following:

• Check for cloud-init: On cloud instances, cloud-init may overwrite hostname on boot.
• NetworkManager: NetworkManager may reset hostname if configured to do so.
• Permissions: Ensure you run commands as root or with sudo.
• Check /etc/hosts: Incorrect entries here can cause hostname resolution problems.
• Reboot or restart services: Sometimes a reboot or restarting related services is necessary.

Important: Avoid using spaces or special characters in hostnames to ensure compatibility.

Summary

Changing the Linux server hostname is a straightforward process but requires care to ensure persistence and consistency across services.

Key steps to remember:

1. Check your current hostname with hostname or hostnamectl status.
2. Change hostname temporarily with hostname new-hostname or permanently with hostnamectl set-hostname new-hostname.
3. Manually edit /etc/hostname and /etc/hosts if necessary.
4. Reboot or restart services to apply the changes.
5. Verify the hostname after reboot.

Following these guidelines will keep your Linux server’s identity clear and consistent within your infrastructure.