Conduct Regular Vulnerability Scans

Regular vulnerability scans help identify and remediate security flaws before attackers exploit them. These scans:

✅ Detect outdated software, misconfigurations, and security weaknesses.
✅ Help ensure compliance with security frameworks (PCI-DSS, HIPAA, ISO 27001).
✅ Provide proactive defense by addressing vulnerabilities before they become threats.

By running scheduled scans, you reduce attack surfaces and strengthen system security.

How to Perform Vulnerability Scans in Linux

1. Install OpenVAS (Open Vulnerability Assessment System)

OpenVAS is an open-source vulnerability scanner that detects known security flaws.

Install OpenVAS on Debian/Ubuntu

sudo apt update && sudo apt install openvas -y

For CentOS/RHEL, install from source using Greenbone Security tools.

Start OpenVAS Services

sudo systemctl start openvas-scanner
sudo systemctl enable openvas-scanner

Run OpenVAS Initial Setup

sudo greenbone-feed-sync

(This updates vulnerability definitions.)

Access OpenVAS Web Interface

1. Open a web browser and go to:

   https://your-server-ip:9392
   

2. Log in with default credentials (admin/admin after setup).

3. Start a scan by selecting New Task → Full Scan on your server's IP.

4. Review results and address vulnerabilities.

2. Install and Use Nessus for Advanced Vulnerability Scanning

Nessus is a powerful enterprise-grade vulnerability scanner that offers detailed security assessments.

Download and Install Nessus

For Debian/Ubuntu:

wget https://www.tenable.com/downloads/api/v1/public/pages/nessus/downloads/14704/download?i_agree_to_tenable_license_agreement=true -O Nessus.deb
sudo dpkg -i Nessus.deb

For CentOS/RHEL:

wget https://www.tenable.com/downloads/api/v1/public/pages/nessus/downloads/14706/download?i_agree_to_tenable_license_agreement=true -O Nessus.rpm
sudo rpm -ivh Nessus.rpm

Start the Nessus Service

sudo systemctl start nessusd
sudo systemctl enable nessusd

Access the Nessus Web Interface

1. Open a web browser and go to:

   https://your-server-ip:8834
   

2. Create an account and select Nessus Essentials (free) or Nessus Professional.

3. Update plugins and start a new scan to analyze system vulnerabilities.

3. Automate Weekly Vulnerability Scans

Schedule a weekly scan using OpenVAS or Nessus with a cron job:

sudo crontab -e

Add the following line to run OpenVAS weekly at 2 AM on Sundays:

0 2 * * 0 openvas-scan-command

(Replace openvas-scan-command with the actual command from OpenVAS API or CLI.)

For Nessus scans, use:

/opt/nessus/bin/nessuscli scan run --target=your-server-ip

4. Review and Address Vulnerabilities

After each scan:
✅ Review security reports and identify critical vulnerabilities.
✅ Apply software patches and security updates (sudo apt update && sudo apt upgrade -y).
✅ Restrict unnecessary services and ports (use sudo ufw status or sudo ss -tuln).
✅ Monitor logs and intrusion attempts (sudo cat /var/log/auth.log | grep failed).

Best Practices for Vulnerability Management

🔹 Run scans at least once a month or after major system updates.
🔹 Use a combination of tools (OpenVAS, Nessus, and Nmap) for comprehensive security checks.
🔹 Fix high-risk vulnerabilities immediately to prevent exploitation.
🔹 Monitor and log scan results to track security improvements over time.

By conducting regular vulnerability scans, you proactively detect and fix security weaknesses, reducing the risk of breaches and strengthening your Linux server’s security posture.