Home Security Protect Your Network with Open-Source Penetration Testing Tools

Protect Your Network with Open-Source Penetration Testing Tools

by Subho Halder
1.5K views 5 mins read
Open-Source Penetration Testing Tools

Cybercrime is a growing menace that has created unprecedented financial losses for organizations. The average cost of these crimes hovers around an alarming $13 million and shows no signs of abating as more attacks are reported each year, exposing new vulnerabilities in the system.

Cybersecurity Ventures’ Official Cybercrime Report for 2022 predicts a devastating hike in damages due to cybercrimes- from a sweeping $8 trillion in 2023 up to an alarming $10.5 trillion by 2025.

Your business could face severe reputational and financial damages if it falls victim to a cyber-attack. Fortunately, you can defend against such dangerous threats with the help of penetration testing! With open-source tools, this practice allows businesses to identify existing vulnerabilities in their networks/apps/websites – helping them make more robust security measures for superior protection.

But which open-source pen testing tools can you trust? Well, we got you covered. In this article, we’ll cover penetration testing, how it works, why it’s important, and list some industry-leading pen testing tools. You can compare the available options and make an informed decision.

What is Penetration Testing?

Penetration testing is a security procedure for identifying system, network, website, or application vulnerabilities. Penetration tests are conducted by qualified security professionals who mimic the behavior of an actual hacker. They approach the system and exploit the vulnerabilities like a hacker would do in real time.

Pen testing is also known as ethical hacking because security professionals exploit the system for ethical purposes in a controlled manner. The purpose is to identify and fix the vulnerabilities before a real hacker exploits them.

How Does Penetration Testing Work?

Although the actual process of penetration testing might vary from organization to organization, here’s how it typically works:


The first step in penetration testing is reconnaissance, collecting information about the target network, app, or system, such as IP, OS, etc. When the pen tester better understands the target, detecting unknown vulnerabilities becomes easier.


Once the pen tester has the required information at hand, they begin scanning the system or network for vulnerabilities. Usually, different tools, such as Nmap, Wireshark, etc., are brought into use for:

  • Port Scanning
  • Vulnerability Scanning
  • Network Mapping
  • Wireless Network Scanning
  • Web Application Scanning

Vulnerability Assessment

Majorly, this process involves prioritizing the identified vulnerabilities based on the risk they pose. This makes it easy to exploit them further and mitigate them.


Exploitation is the most critical stage of open testing. In this stage, the pen tester tries to exploit the identified vulnerabilities. The primary goal here is to act as an actual attacker and demonstrate the impact of an exploit on the system or network. This process usually involves:

  • Gaining Initial Access: The pen tester tries to exploit the weakness and gain unauthorized access.
  • Increasing the Privileges: After gaining access, the tester attempts to get further access and control over the network.
  • Expansion of the Attack: The tester then tries to connect to other networks/systems via the original target system/network to expand the scope of the attack.
  • Maintaining access: The tester tries to maintain continuous access to the network.

Reporting and Remediation

Reporting and remediation is the final stage of penetration testing, wherein the pen tester creates a detailed report that includes all the findings. This report is handed to the technical staff so they can make the necessary changes and make their system or network more secure.

Why is Penetration Testing Important?

Here’s why:

  • Real-World Simulation: With penetration testing, you can simulate a real-world attack which gives you a more accurate view of how a hacker may attempt to exploit your network. And this is something you cannot do using traditional methods.
  • Hidden Vulnerabilities: Security penetration testing allows you to uncover vulnerabilities often missed by network monitoring or vulnerability scans. This way, you can fix the vulnerabilities before they can be exploited.
  • Mandatory for Compliance: Several industry standards and regulations, such as PCI DSS, HIPAA, GDPR, etc., have mandated penetration testing for compliance. It means your organization must perform regular pen tests to comply with the aforementioned regulations and to stay operational.

Now that you know the importance of penetration testing, let’s learn about some open-source pen testing tools.

Top 6 Open-Source Penetration Testing Tools


Nmap, aka network mapper, is one of the best penetration test tools known primarily for scanning or reconnaissance. Using Nmap, you can scan large networks easily and quickly and gather information about the hosts and services active on the network.

Nmap runs on most operating systems and is easy to use. In addition, it has decent documentation and plenty of tutorials. So, learning and using Nmap won’t be a problem.


Appknox is a plug-and-play security platform using which you can substantially boost your network or application security. In just a few clicks on our dashboard, you can book a penetration test with dedicated researchers who have uncovered vulnerabilities in popular apps such as Facebook, Walmart, Skype, Snapchat, and more! These experts will examine each layer of your platform for potential weaknesses before delivering an extensive report covering their findings. 

In addition to helping you with penetration testing tools, Appknox also offers the following:

  • Static Application Security Testing (SAST)
  • Dynamic Application Security Testing (DAST)
  • API Security Testing


Yet another open-source pen-testing tool is Wireshark. It’s a network protocol analyzer using which you can capture and analyze network packets. You can identify and deal with potential vulnerabilities by analyzing the network packets.

The best part, Wireshark is easy to learn. Also, there are several courses available that you can use to make the most of this network scanning tool.


Distributed by Greenhouse Networks, OpenVAS is a set of several built-in tests & a web interface. It allows you to detect, assess and mitigate vulnerabilities on a network. Using OpenVAS, you can scan visible ports and services for known exploits and detect high-level threats such as cross-site script, improper file access, etc.

Its vast database includes several vulnerabilities you can customize per your needs, making vulnerability testing easier.


Jok3r is an open-source network and web pen test automation framework for developers and security testers. It helps combine multiple security testing tools, automate penetration tests, and helps identify & exploit vulnerabilities in the network. 

However, using Jok3r is tricky compared to other tools as it’s a framework. You’ll have to pull the Docker image using the command line.


Legion is an easy-to-use, extensible, and open-source network penetration testing software. It is semi-automated and helps with reconnaissance, information system exploitation, and identifying potential vulnerabilities.

The rich GUI helps complete the tasks efficiently without having to refer to the documentation. Also, this tool is customizable and automatically links common vulnerabilities and exposures with its database.

Which Open-Source Penetration Testing Tool is the Best?

When deciding on a pen testing tool, your specific needs should be taken into consideration. For example, if you’re seeking an efficient option for network scans, Nmap is a perfect choice. But for more comprehensive security assessment and testing capabilities, Appknox provides unbeatable results!

As you consider the options out there, be sure to consider all your needs: the scope of your project, specific features required, and customer support. After thoroughly comparing each tool against these criteria, select the one best suited for you!

Wrapping Up

Leveraging open-source penetration testing tools is recommended to keep your network, mobile and web applications safe from cyber threats.

Before implementation, be sure to carefully evaluate available options to maximize the value of this exercise. If it’s not feasible for you to implement pen tests in-house, consider engaging a specialized vendor. In that case, this could translate into even greater assurance while saving resources simultaneously!

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