Rename MySQL Root User: Security Best Practice

TL;DR

Yes, renaming your MySQL root user is a good security practice. It makes it harder for attackers to guess the username and reduces the risk of automated attacks. This guide shows you how to do it safely.

How to Rename Your MySQL Root User

1. Connect to MySQL as Root: Use your preferred method (command line, phpMyAdmin, etc.). For example, using the command line:

   mysql -u root -p

2. Check Existing Users: Before renaming, confirm you’re only changing the root user. List all users:

   SELECT User, Host FROM mysql.user;

3. Rename the Root User: Use the RENAME USER statement. Replace ‘old_root_username’ with your current root username (usually ‘root’) and ‘new_root_username’ with your desired new username.

   RENAME USER 'old_root_username'@'localhost' TO 'new_root_username'@'localhost';

   Important: The @'localhost' part specifies the host. If root has access from other hosts (e.g., ‘%’), you need to rename it for each host separately.

4. Update Grants (if necessary): After renaming, some grants might still refer to the old username. Check and update them if needed.

   SHOW GRANTS FOR 'old_root_username'@'localhost';

   If you find any grants referencing the old user, revoke them and re-grant them to the new user.

   REVOKE ALL PRIVILEGES ON *.* FROM 'old_root_username'@'localhost';
   GRANT ALL PRIVILEGES ON *.* TO 'new_root_username'@'localhost';

5. Flush Privileges: This reloads the grant tables so MySQL uses the updated information.

   FLUSH PRIVILEGES;

6. Test the New User: Disconnect and reconnect using the new username and password to verify it works correctly.

   mysql -u 'new_root_username' -p

7. Consider Additional Security Measures: Renaming is just one step. Also:
   • Use a strong, unique password for the root user.
   • Limit root access to specific hosts if possible (avoid ‘%’).
   • Create separate users with limited privileges for applications and tasks.

Important Notes

• Backup: Always back up your MySQL database before making any changes to user accounts or permissions.
• Host Specification: Pay close attention to the host part of the username (e.g., ‘localhost’, ‘%’). You need to rename the user for each host it has access from.
• phpMyAdmin: If using phpMyAdmin, navigate to the Users section, select the root user, edit its username, and save the changes. Remember to flush privileges afterwards.