Running a VPS can be risky if you do not go through with some basic security measures before using it. Here are a few tips to get you started in securing your server.
That's it for now, but your journey does not have to end there. Linux servers have many methods of security and possible solutions are only a click away with a web search.
- Make sure you have a secure SSH login password for all accounts. Do not use anything that would be obvious or can be easily guessed.
- You can change your SSH password by typing in the following command: passwd
- Protect your SSH from brute force attempts with Fail2Ban using this guide.
- Change the default port of your SSH service. Instead of using the common port 22, set it to a different port via the config file for your SSH service (this varies between Linux distributions).
- With CentOS, you can change the SSH port in the /etc/ssh/sshd_config file. Just uncomment the line for the port and set it to a value you want. Then restart the SSHd service with this command: /etc/init.d/sshd restart
- Disable any unnecessary services on your server after a fresh install. For example, some distributions of Linux will have the "httpd" (web server) service installed and running by default - you will want to disable that if you do not intend to use it. Please refer to your distro's manuals/guides on how to shut off services/processes.
- Always try to run services as a non-root user if possible.
- You can create non root users with the useradd username command and set their password with the passwd username command.
- Whitelist SSH access. You can use your hosts.allow and hosts.deny files on your server (both usually in the /etc folder) to allow access to SSH on authorized IPs only. You would want to have the "sshd: ALL" line in the hosts.deny file and "sshd: YOURIP" in the hosts.allow file (this may vary depending on the Linux distro). This can also be done via iptables.
- Use iptables to restrict ports/IP and firewall your server against basic network attacks (this can be very complex - you will want to do your research before jumping into this).