What are the best practices to avoid my server being port scanned

Question

Port scanning can reveal services that attackers might target. What are some effective ways to reduce exposure to port scans or block them altogether?

Answer 1

​Port scanning is a technique used by attackers to identify open ports and services on a server, potentially exposing vulnerabilities. To reduce exposure to port scans or block them altogether, consider implementing the following best practices:​

1. Configure Firewalls to Restrict Access

Utilize firewalls to control incoming and outgoing traffic based on predetermined security rules:​

• Block Unnecessary Ports: Close all non-essential ports to minimize potential entry points for attackers.

• Restrict Access: Limit access to sensitive services by allowing only trusted IP addresses or networks.​

• Implement Intrusion Prevention Systems (IPS): Deploy systems that can detect and block port scanning activities in real-time.​

2. Employ Port Knocking Techniques

Port knocking adds an additional layer of security by keeping ports closed until a specific sequence of connection attempts is made:​

• Dynamic Port Access: Configure services to remain hidden until a predefined sequence of connection attempts (knocks) is received, after which the port opens for the requester.​

3. Use Tools to Detect and Respond to Scans

Implement software that monitors and responds to port scanning attempts:​

• Install Port Scan Detection Tools: Tools like 'psad' (Port Scan Attack Detector) analyze firewall logs to detect and alert on port scan activities.

• Configure Automated Responses: Set up systems to automatically block IP addresses that exhibit suspicious scanning behavior.​

4. Regularly Update and Patch Systems

Keep all software and systems updated to protect against known vulnerabilities:​

• Apply Security Patches Promptly: Regularly update operating systems, applications, and security tools to their latest versions.​

• Monitor Vulnerability Reports: Stay informed about new vulnerabilities and apply necessary mitigations.​

5. Conduct Regular Security Audits

Regular assessments help identify and mitigate potential security gaps:​

• Perform Internal Port Scans: Regularly scan your own network to identify and address open ports and vulnerabilities.​

• Review Firewall and Security Configurations: Ensure that security settings align with best practices and organizational policies.​

Implementing these strategies can significantly reduce your server's exposure to port scanning activities and enhance overall security.