Linux Server Security Guide: Part 3

Network Security

When it comes to network security, your firewall is one of your most important tools. It is generally a good idea to have multiple lines of defense, such as a router-level firewall and also a server-level firewall that is software-based. Usually, you can block most ports with your firewall, and only allow the ports you need for server functionality to remain open.

Beyond basic port protection, firewalls can also include other features, such as early intrusion detection and DoS protection.

The Linux kernel includes a firewall system that is accessible through iptables. The kernel-based firewall is known to be secure but also somewhat cumbersome to manage without other tools. You may benefit from using a third-party firewall tool like APF.

For more advanced network security, you can use a vulnerability scanner that will detect weak points in your server. These tools often do more than network scans, also checking your logs, operating system, and even applications.