Switching the SmarterMail service from running under the 'root' user to a dedicated user is recommended for enhancing security. In a Linux environment, 'root' is like 'admin' - the default, and rather generic, user that most applications are installed using. It also can give control of an entire Linux system if the 'root' account is compromised. Therefore, changing the owner of a service from 'root' to a different user minimizes the risk of potential security breaches should that service get compromised by restricting the service’s permissions and limiting the impact of any vulnerabilities.
Why Use a Dedicated User?
Running SmarterMail under a dedicated user rather than 'root' helps:
- Reduce Security Risks: If SmarterMail is compromised, the attacker’s access will be limited to what the dedicated user can access, not the entire system.
- Improve Access Control: You can more finely tune permissions and ownership over SmarterMail-related directories and files, ensuring that only SmarterMail can access its necessary components.
- Compliance with Best Practices: Operating services under their own user account is a well-established best practice in system administration, helping to keep your server secure and organized.
Changing Ownership of Service
1. You’ll want to ensure the dedicated user exists. To create a suitable user named ‘smartermail’, run the following command:
sudo useradd -m -d /etc/smartermail smartermail
2. Next, stop the SmarterMail service:
sudo service smartermail stop
3. Now open SmarterMail’s service file:
sudo nano /etc/systemd/system/smartermail.service
4. Add the following directives to the bottom of the [Services] section (replace 'smartermail' with the name of your user):
User=smartermail AmbientCapabilities=CAP_NET_BIND_SERVICE
5. Reload the systemd Daemon:
sudo systemctl daemon-reload
6. Next, you'll want to change ownership of SmarterMail’s directories to the user you've created.
Changing Ownership of Directories
Run the following 4 commands in your shell to ensure SmarterMail’s service has access to the requisite directories:
sudo chown -R smartermail:smartermail /opt/smartermail
sudo chown -R smartermail:smartermail /var/lib/smartermail
sudo chown -R smartermail:smartermail /etc/smartermail
sudo chown -R smartermail:smartermail /tmp/publicsuffixcache.dat
Restart Service
Run the following command to restart the service:
sudo systemctl restart smartermail
Verify the Service is Running:
systemctl status smartermail
Finally, verify the service is running under the new user:
ps -o user,group,pid,cmd -p $(pgrep MailService)