Change a Linux server’s hostname

By default, your server is started with the server’s given name as the hostname. Some software such as cPanel® requires a valid fully qualified domain name (FQDN) for the hostname to be used during their licensing verification system. This article describes how to change a server hostname in Linux®.

Change a server’s hostname

1. Check existing hostname

   $ hostname
   

2. Modify the value to match your FQDN hostname, as shown in the following example:

   $  hostnamectl set-hostname NEW-HOST
   $  hostname
   NEW-HOST
   

3. Open the file at /etc/hosts. To update the information for internal networking, change the host that is associated with the main IP address for your server, as shown in the following example:

   $  vim /etc/hosts    
   127.0.0.1      localhost localhost.localdomain
   123.45.67.89   hostname.domain.com   hostname
   

4. Change the domain name (where required)

   $  vim /etc/resolv.conf
   domain abc.com            <--- This would be the domain.
   nameserver 173.203.4.8
   nameserver 173.203.4.9
   

5. Change networking configuration /etc/sysconfig/network

   $  vim /etc/sysconfig/network
   NETWORKING=yes
   FORWARD_IPV4=false
   HOSTNAME=hostname.domainname.com   <---- change this bit (FQDN)
   DOMAINNAME=domainname.com          <---- change this bit if the domain name has changed
   GATEWAY=172.0.0.1
   GATEWAYDEV=eth0
   

6. Change networking configuration /etc/sysconfig/network

   $  vim /etc/hostname
   hostname.domainname.com
   

7. Update the Mail Transfer Agent (MTA) configuration.

   $  vim /etc/postfix/mydomains
   mydomains - included a list of aliases for your machine here, formatted:
   example.com                                   OK
   After change, run 'postmap /etc/postfix/mydomains'
   localhost                                     OK
   #myoldserver.domain.com                       OK <------ commented out
   myserver.domain.com                           OK <----- added in
   

   Update the hostname in Postfix if it is hadcoded in and restart the service

   $  vim /etc/postfix/main.cf
   $  postmap /etc/postfix/main.cf
   $  systemctl restart postfix
   

   NOTE: This file can have quite a bit of information. You can grep for ‘hostname’ for faster results.

   $  grep 'hostname' /etc/postfix/main.cnf
   $  cat /etc/postfix/main.cnf | grep hostname
   

8. Update MySQL, MariaDB or Percona - Check the user table for the old hostname.

   $  mysql -e "SELECT DISTINCT host FROM mysql.user;"
   

   If binary logging is enabled and the log files named using the original hostname then you must update /etc/my.cnf or binary logging will break and possibly have replication. You must specify the filename of the existing files, i.e. the old hostname

   $  grep  -E 'log-bin|relay-log' /etc/my.cnf /etc/mysql/my.cnf
   log-bin=/var/lib/mysqllogs/oldlogfilename
   relay-log=/var/lib/mysqllogs/oldrelaylogfilename
   

9. Restart syslog

   $  service rsyslog restart    
   or
   $  systemctl restart rsyslog
   

Related Articles

• Change a server hostname in the Ubuntu operating system
• Cloud Servers Articles

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