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When setting up and testing a network security system, it is critical to make sure it is working properly and free from vulnerabilities that could be exploited by malicious hackers. While the best way to guarantee the security of a system is to design, implement and operate it to be secure, continuously testing a network security system for potential flaws is an excellent way to improve and validate network security - which is where pentesting comes in quite handy. This article will introduce the concept of pentesting to improve and verify network security, explain basic pentesting methodology and explore some excellent pentesting tools, distros and OSes available to Linux users in 2021.


What Is Pentesting & How Does It Work?

Pentesting, or ethical hacking, is the practice of carrying out staged cybersecurity attacks that mimic an actual security incident with the aim of identifying weak points in a security system that a malicious hacker could exploit. Pentests can vary greatly depending on the type of attack that is launched, the information that the ethical hacker is able to obtain beforehand and the limitations put in place by their employer. However, the majority of pentests fall into one or multiple of the following categories:

  • Insider pentests simulate an insider attack, where a malicious hacker poses as a legitimate employee to gain access to the company’s internal network. This type of pentest relies on finding internal security issues such as access privilege and network monitoring flaws, rather than external vulnerabilities like firewall, antivirus, and endpoint protection issues.
  • Outsider pentests don’t give hackers any access to the company’s internal network or employees, forcing him or her to get in through external means such as public websites or open communication ports. This type of pentest can overlap with social engineering pentests in which a hacker evades external protection by tricking an employee into granting them access to the company’s internal network.
  • Data-driven pentests provide the hacker with security information about the target. This type of penetest simulates an attack carried out by either a former employee or someone who obtained leaked security data.
  • Blind pentests give the hacker no information whatsoever about the target other than their name and what’s publicly available.
  • Double-blind pentests test security and IT staff along with digital security measures. In this type of pentest, no one in the company is aware of the simulated attack, forcing them to react as they would if they encountered a malicious cyberattack. Double-blind pentests provide valuable information on a company’s overall security posture - including its staff’s readiness.

Pentesting Methodology

Just like malicious cyberattacks, pentests require careful planning to be successful, and follow a sequence of clearly-defined steps in order to yield the data and insights sought by the pentester. To help you gain a better understanding of how pentesting works, let’s examine basic pentesting methodology.

  1. Gather Information & Planning: The ethical hacker gathers information on the target and plans the point of attack around it.
  2. Vulnerability Evaluation: He or she then scans the point of attack, looking for vulnerabilities to exploit and running multiple small-scale tests to see how the security system reacts.
  3. Vulnerability Exploitation: After finding the right entry point(s), the hacker tries to penetrate the target’s security system and access the network.
  4. Maintaining Covert Access: If the hacker is able to evade security defenses and access the network, he or she then attempts to stay inside the network undetected long enough to achieve the specified goal of the pentest (leaking data, compromising systems and/or files, installing malware, etc.).
  5. Reporting, Analyzing & Repairing: Whether the attack was successful or not, the hacker reports the findings to his or her employer. Security professionals then analyze the attack data, compare it to what their monitoring systems report and implement proper modifications to improve security defenses.
  6. “Rinse & Repeat”: Companies will often test the improvements they make to their security system by staging another pentest.

How Can Pentesting Be Used to Improve & Verify Network Security?

As you can see, pentesting is an important component of a successful network security strategy. It identifies weak points (or a lack thereof) in a network, providing security professionals with valuable data that they can compare to data provided by network monitoring systems. The insight gained through pentesting allows administrators to implement proper modifications to improve network security systems, addressing vulnerabilities before they are exploited by malicious hackers. Pentesting is also a great method of testing improvements that companies make to their network security systems and verifying that, with these modifications, their security systems are now capable of preventing malicious attacks.

Our Top Two Tools, Distros and OSes for Pentesting on Linux in 2021

Kali Linux

Kali Linux is one of the most popular Linux distros among pentesters and security researchers. It is flexible, customizable and full-featured, and protects sensitive pentesting data with LUKS full-disk encryption.

You can download Kali Linux downloads.

Parrot Security OS

Parrot Security OS is a free Linux-based OS designed for pentesting, reverse engineering and digital forensics. It is lightweight, user-friendly and supports a wide selection of open-source pentesting and software development tools and utilities. Parrot Security OS is known for the impressive security and control it provides users. It is always updated, frequently released and offers an array of hardening and sandboxing options.

You can download Parrot Security OS Parrot Security OS downloads.


Nmap (“Network Mapper”) is an open-source intelligence (OSINT) network monitoring tool that collects and analyzes data about a device’s hosts and servers. The popular utility is flexible, powerful and user-friendly, earning it numerous awards, including "Information Security Product of the Year" by Linux Journal, Info World and Codetalker Digest.

You can download Nmap nmap downloads.


WebShag is an OSINT system auditing tool that scans HTTPS and HTTP protocols, collecting relative data. It is used by ethical hackers performing outsider pentests through public websites.

Key Takeaways

Pentesting, or the practice of staging cyberattacks that mimic legitimate security incidents, can help improve network security by allowing administrators to identify and improve weak points in network security systems, and verify that the modifications they make are working as they should to prevent future attacks. There are many excellent tools, distros and OSes designed to assist in the pentesting process available to Linux users - Kali Linux, Parrot Security OS, Nmap and WebShag being among our favorites. Pentesting requires careful planning and methodology, and should be one element of a comprehensive, defense-in-depth approach to network security.

Are you using pentesting to help assess, improve and verify the security of your network? We want to hear about your experience! Connect with us on social media:

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