• Vulnerabilities that could allow unauthorized control or access to sensitive data on a system
• Misconfiguration (e.g. open mail relay)
• Denials of service (Dos) vulnerabilities
• Default passwords, a few common passwords, and blank/absent passwords on some system accounts
• Outbound or inbound connections, TCP or UDP, to or from any ports
• Full DNS forward/reverse checking, with appropriate warnings
• Ability to use any local source port
• Ability to use any locally configured network source address
• Built-in port-scanning capabilities, with randomization
• Hex dump of transmitted and received data
• Optional ability to let another program service establish connections
• Optional telnet-options responder

1. Scanning for Vulnerabilities : Nessus performs security scans on computers and networks, checking for vulnerabilities that hackers could exploit.
2. Port and Service Analysis : It tests each port on a system, determines the services running, and checks for security flaws.
3. Security Alerts : If Nessus detects a vulnerability, it raises an alert, allowing administrators to take action.
4. Compliance and Risk Assessment : Nessus helps organizations comply with security standards by identifying misconfigurations, missing patches, and weak passwords.
5. Reporting and Remediation : The tool provides detailed reports on vulnerabilities and suggests fixes.

1. Nessus is quite expandable : Once developers become more accustomed to the tool, it provides a scripting language that allows you to create system-specific tests. It also features a plug-in mechanism, and the Nessus website for plug-ins provides many free plug-ins. These plugs frequently focus on identifying a particular infection or vulnerability.
2. It is available in the public domain : Nessus is free and open source. Thus, you can view and alter the source code as you choose.
3. You can gain from patching assistance : Nessus frequently can recommend the best course of action for mitigating a vulnerability when it is discovered.
4. It’s built by proven practitioners : Nessus was created from the ground up with a thorough knowledge of how security professionals operate. Nessus was designed to make vulnerability simple, straightforward, and user-friendly. One will require less time and effort to evaluate, rank, and address problems. Click here to read more about the features.

Nessus is a powerful vulnerability assessment tool used to identify and manage security risks. Here are some examples of its usage :

Basic Examples

1. Running a Basic Network Scan :
• Log in to the Nessus web interface.
• Create a new scan using the "Basic Network Scan" template.
• Specify the target IP address or range (e.g., 192.168.1.0/24).
• Launch the scan and review the results for vulnerabilities.
2. Credentialed Scans :
• Configure credentials (e.g., SSH or Windows credentials) in the scan settings.
• Perform a credentialed scan to get deeper insights into vulnerabilities, such as missing patches or misconfigurations.
3. Exporting Scan Results :
• After completing a scan, export the results in formats like PDF, CSV, or HTML for reporting and analysis.
4. Policy Compliance Checks :
• Use compliance templates to check systems against security standards like PCI DSS or CIS benchmarks.

Advanced Examples

1. Custom Scan Policies :
• Create a custom scan policy to tailor the scan settings for specific environments or requirements.
• For example, exclude certain IPs or ports from the scan.
2. Web Application Scanning :
• Use Nessus to scan web applications for vulnerabilities like SQL injection or cross-site scripting (XSS).
3. Integration with SIEM :
• Integrate Nessus with a Security Information and Event Management (SIEM) tool to correlate scan results with other security events.
4. Automated Scans :
• Schedule scans to run automatically at regular intervals, ensuring continuous monitoring of vulnerabilities.

Practical Applications

• Vulnerability Management : Identify and prioritize vulnerabilities in your network.
• Compliance Auditing : Ensure systems meet regulatory and security standards.
• Incident Response : Use Nessus to identify vulnerabilities exploited during a security breach.

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Terminal Installation Commands ...
GUI Installation Steps ...

Linux

1. Download the Nessus package for your Linux distribution.
2. Run the installation command based on your OS :
   • Debian/Kali/Ubuntu : dpkg -i Nessus-<version>.deb
   • Red Hat/CentOS : yum install Nessus-<version>.rpm
   • SUSE : zypper install Nessus-<version>.rpm
3. Start the Nessus service : systemctl start nessusd
4. Open Nessus in your browser : https://localhost:8834
5. Complete the setup in the web interface.

Windows

1. Download the Nessus installer for Windows.
2. Run the .exe file and follow the installation wizard.
3. Open Nessus in your browser : https://localhost:8834
4. Complete the setup.

MacOS

1. Download the Nessus .dmg file.
2. Open the file and drag Nessus into the Applications folder.
3. Start Nessus and complete the setup via https://localhost:8834.

Terminal Uninstallation Commands ...
GUI Uninstallation Steps ...

Linux

1. Stop the Nessus service : systemctl stop nessusd
2. Remove Nessus : yum remove Nessus (Red Hat-based) or dpkg --purge Nessus (Debian-based)
3. Delete Nessus data : rm -rf /opt/nessus

Windows

1. Open Control Panel > Programs and Features.
2. Find Tenable Nessus, right-click, and select Uninstall.
3. Delete leftover files from C:\Program Files\Tenable\Nessus.

MacOS

1. Open Terminal and run : sudo /Library/Nessus/run/sbin/uninstall.sh
2. Remove Nessus files : rm -rf /Library/Nessus