Enhancing Server Security: Implementation and Evaluation of the Port Knocking Method on Ubuntu Virtual Servers
Sadeer Sadeq, Wid Badee Abdulaziz, Rafid Najm Abdullah Alsaadi, Mabrouka M. A. Algherini · Journal of Engineering and Sustainable Development · 2025
Server security is the most important thing for administrators. The server has service access via port 22, which is the most crucial point to secure because illegal access to the system is common. To overcome this problem, a firewall is implemented to act as a barrier. However, firewall users themselves are still less effective because of how it works, which closes all access without caring about anyone connected to the network. To address these issues, the port-knocking method is used in server security. The technique works by opening and closing Port 22 blocks using a firewall that detects knock attempts on network devices. Tests were conducted using port scanning, a DDoS attack, and brute-force attacks to evaluate the port-knocking method's performance in securing the server. With many tests —30, 15, and 26 times—success percentages of 0%, 90%, and 100%, the port knocking method can secure the server against unauthorized access and overcome problems caused by firewalls.