This is a starting point of best practices for hardening a production server. Topics include user accounts, an iptables firewall, SSH and disabling unused network services.
How to use two-factor authentication and other security controls in the Linode Manager.
A collection of security practices to help you prevent common system exploits.
Steps to take if your Linode becomes compromised by unauthorized parties.
Access your Linode via SSH using Public Key Authentication.
Generate a GPG key-pair, and convert it to an SSH key for authentication with your Linode.
Full Disk Encryption.
Install and configure OSSEC HIDS on Debian 7
Use Fail2ban to block automated system attacks and further harden your server. Fail2ban monitors system logs for symptoms of an automated attack, bans the IP and alerts you of the attach through email.