The 25 Best Open Source Security Tools To Protect Your System

Security tools are computer programs that allow us to find
vulnerabilities in software. Malicious users use them to gain
unauthorized access to information systems, enterprise networks, or
even personal workstations. Security researchers, on the other
hand, use these tools to find bugs in software so that companies
can patch them before exploitation could take place. There is a
wide range of open source security tools that are used by both the
bad guys and penetration testing professionals. Today, we have
compiled a list of 25 such programs that have widespread usage in
computer security and other related fields.

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Some
security tools are used extensively for escalating security
privileges, whereas there are many tools that aim to provide
defensive capabilities against such breaches. Our editors have
chosen their picks from both sides so that you can have a clear
understanding of standard security-related problems.

1. Metasploit

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The Metasploit Project is, without any doubt, one of the best
security projects of modern times. At its heart, sits the
Metasploit framework, an extremely powerful tool that allows users
to manage and maintain their security workflows at ease. The core
solution is available freely in GitHub.

So, interested users can view the source themselves and gain a
better understanding of how it works. Most penetration testers use
this framework to carry out professional security auditing tasks
due to its immense number of features and capabilities.

Features of Metasploit

• Metasploit helps security professionals in automating the
  various stages of penetration testing through its robust
  modules.
• It allows users to perform sophisticated network attacks such
  as website cloning, cross-site scripting, and phishing
  campaigns.
• The Metasploit framework is written using the Ruby scripting language^[1], which makes it very
  easy to extend this tool.
• Enterprises can opt-in for the premium version of Metasploit
  for ensuring maximum operability and technical support.

Download Metasploit ^[2]

2. Nmap

---

Nmap is a compelling network scanner that is widely used by
security professionals and malicious users. It allows us to scan
hosts for open ports, vulnerable services, and OS detection. Most
hackers will use Nmap at the starting phase of their attack since
it provides them the essential information required to take down
remote systems. Although it is a command-line tool, there is a nice
GUI interface called Zenmap^[3]. Additionally, a large number of Nmap commands^[4] help people discover
sensitive information about remote users and networks.

Features of Nmap

• Nmap enables users to discover available hosts in a computer
  network by sending TCP/IP network requests.
• It makes it easy to enumerate over port lists and identify
  whether certain ports are open or filtered.
• Security professionals can obtain important information like OS
  version, running services, and the presence of IDS mechanisms.
• The NSE(Nmap Scripting Engine) allows users to write customized
  scripts using the Lua programming language.

Download Nmap^[5]

3. OSSEC

---

OSSEC or Open Source Host-based Intrusion Detection System is a
modern-day IDS that helps professionals discover security problems
in enterprise servers. It allows users to analyze system logs,
perform integrity checks, monitor the Windows registry, and many
more. OSSEC also enables us to find the presence of any potential
rootkits and provides excellent alerting mechanisms. Many
corporations have started to use OSSEC for detecting hard to catch
problems due to its diverse capabilities and rich feature set.

Features of OSSEC

• OSSEC allows security professionals to maintain industry
  compliances by detecting unauthorized changes in system files and
  configurations.
• The Active Response feature of OSSEC makes sure immediate steps
  are taken as soon as a security vulnerability arises.
• It provides real-time alerts on intrusion detection and can be
  integrated with existing SIM(Security Incident Management)
  solutions very easily.
• The open-source nature of this project allows developers to
  customize or modify the software as they require.

Download OSSEC^[6]

4. OWASP ZAP

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OWASP ZAP or Zed Attack Proxy is an excellent security scanner
program for modern web applications. It is developed and maintained
by a team of internationally recognized security experts. Zed
Attack Proxy allows admins to find a large number of common
security vulnerabilities. It is written using the Java programming
language and offers both graphical and command-line interfaces.
Moreover, you don’t need to be a certified security professional for
using this software since it is very straightforward for even
absolute beginners. ^[7]

Features of OWASP ZAP

• Zed Attack Proxy can find security flaws in web applications
  during both the development phase and testing phase.
• It exposes compelling REST-based APIs which allow admins to
  automate complex security scanning workflows at ease.
• The ZAP marketplace offers a large number of powerful add-ons
  that can enhance the functionality of this program.
• Its open source license allows developers to customize this
  Linux vulnerability scanner without any legal hassles.

Download OWASP ZAP^[8]

5. Security Onion

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Security Onion is one of the best security platforms for
enterprise environments due to its rich feature set and powerful monitoring tools^[9]. It’s a standalone Linux
distribution developed specifically for intrusion detection, log
management, and security assessment. Security Onion comes
pre-equipped with a large number of open source security tools like
NetworkMiner, Logstash, and CyberChef. Our editors really liked
this security-focused Linux
distribution^[10] due to its ease of use.
It is the perfect solution for businesses that are looking for
enforcing security standards.

Features of Security Onion

• It is a full-fledged Linux distribution aimed at enterprise
  network security, not a standalone scanning application.
• Security Onion is very easy to install and set up even for
  people with little or no prior experience of security tools.
• It can capture and analyze full network packets, session data,
  transaction data, network logs, and HIDS alerts.
• The open-source nature of this Linux environment makes it easy
  to customize based on enterprise requirements.

Download Security
Onion^[11]

6. OpenVAS

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OpenVAS is a security testing suite that consists of a large
number of services and tools used in vulnerability assessment. It
started as a fork of Nessus^[12] but has since grown
into a full-fledged vulnerability scanning framework. One excellent
selling point of this software suite is the ability to manage
demanding security services from a web-based dashboard. OpenVAS
works very well when it comes to locating flaws in network servers
and infrastructures. Moreover, its open-source nature makes sure
users can utilize the framework without any limit.

Features of OpenVAS

• The standard web-based dashboard of this Linux vulnerability
  scanner is very intuitive and easy to operate.
• It provides in-depth information about the vulnerabilities it
  finds alongside its CVSS score and risk rating.
• OpenVAS also offers excellent recommendations on how to
  overcome security vulnerabilities based on its impact.
• Third-party developers can easily extend this framework using
  the Nessus Attack Scripting Language or NASL.

Download OpenVAS ^[13]

7. Wireshark

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Wireshark is an open-source packet analyzer that allows users to
view network streams in exceptional detail. It is one of the best
open source security tools for network troubleshooting and analysis
due to its practical use cases. Malicious users often use Wireshark to capture network
packets^[14] and analyze them for
usable sensitive information. It is a multi-platform application
with ready-made packages for different Linux and BSD distributions^[15]. Overall, it is a
future-proof upgrade for people who are working with tools like
tcpdump or tshark.

Features of Wireshark

• Wireshark can capture live packets and analyze them for
  obtaining readable information like plaintext passwords.
• It can save packets, import them from saving files, filter
  them, and even colorize them for a better visual
  representation.
• Wireshark is written using C and C++ programming languages,
  which makes it extremely fast and portable.
• It comes under the open-source GNU GPL license, which allows
  users to view the source and make further customizations.

Download Wireshark^[16]

8. Nikto

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Nikto is a compelling web server scanner that has been gaining
tremendous popularity since its release. It is a command-line tool
that allows admins to check for server misconfigurations, outdated
packages, and buggy CGIs, among many more. The lightweight nature
of Nikto has mainly contributed to its success. Many modern
penetration testers use Nikto as a replacement for larger server
scanners like Zed Attack Proxy (ZAP). Nikto is written using Perl
and runs flawlessly on most Unix-like systems.

Features of Nikto

• Nikto comes with built-in support for HTTP proxies, OpenSSL,
  LibWhisker’s IDS encoding, and integration with Metasploit.
• Its robust template engine makes it easy to create custom scan
  reports and save them in HTML, plaintext, or CSV documents.
• Admins can easily deploy Nikto as a docker container using
  pre-built container images or with custom configurations.
• The freely available source code of Nikto allows developers to
  extend or modify the software as they see fit.

Download Nikto^[17]

9. W3af

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W3af is a highly capable security testing framework for
modern-day web applications. It is an open-source project written
in Python and offers excellent customization opportunities for
developers. W3af can find more than 200 types of security
vulnerabilities including, SQL injections, cross-site scripting,
CSRF, OS commanding, and stack-based buffer overflows. It is a
truly cross-platform software that is very extremely easy to
extend. This is one of the main reasons behind its growing
popularity among security professionals.

Features of W3af

• W3af is extremely extendible and offers a large number of
  pre-built plugins for added functionalities.
• It comes with a centralized knowledge base that stores all
  vulnerabilities and information disclosures effectively.
• The powerful fuzzing engine of W3af allows users to inject
  payloads into any component of an HTTP request.
• Users can receive the output of their web scans in Linux command shells^[18], data files, or
  directly via email.

Download W3af^[19]

10. Wapiti

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Wapiti is another extremely powerful security scanner for
web-based applications. It performs black-box scans to get the list
of all possible URLs, and once successful, it will try to find
vulnerable scripts by injecting payloads to them. Thus, it also
acts like a Fuzzer. Wapiti can be used for detecting several types
of web vulnerabilities such as XSS, Server Side Request
Forgery(SSRF), database injection, and file disclosures. Overall,
it is a very capable program that can find a large number of bugs
pretty easily.

Features of Wapiti

• Wapiti allows several types of authentication methods and the
  ability to suspend or resume scans anytime.
• It can scan web apps very fast and provides different levels of
  verbosity based on user preference.
• Users may choose to highlight any reported vulnerabilities by
  color-coding them in their Linux terminal^[20].
• Wapiti leverages the Nikto vulnerability database for
  pinpointing the presence of potentially risky files.

Download Wapiti^[21]

11. CipherShed

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CipherShed is a modern-day encryption software which
started out as a fork of the now-defunct TrueCrypt Project. It aims
to provide top-notch security to your sensitive data and can be
used for protecting both personal and enterprise systems. This
cross-platform application runs smoothly on all major operating
systems including, Linux and FreeBSD. Moreover, the
open-source nature of this project makes sure developers can easily
access and modify the source code if they intend to. ^[22][23]

Features of CipherShed

• CipherShed comes with an intuitive GUI interface, which makes
  operating this software very easy for professionals.
• It is extremely lightweight and allows users to create secure
  containers holding sensitive information very fast.
• CipherShed allows users to unmount the encrypted volumes for
  moving them someplace safe.
• The encrypted drives can be transported between different
  systems without any compatibility issues.

Download CipherShed^[24]

12. Wfuzz

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Wfuzz is one of the best open source security tools for
brute-forcing web-based applications effectively. It is developed
using Python and provides a simple command-line interface for
managing the program. Wfuzz can expose several types of
vulnerabilities, including SQL injections, LDAP injections, and
cross-site scripting.

Penetration testers often use this tool
for brute forcing HTTP GET and POST parameters, as well as fuzzing
web forms. So, if you’re looking for a lightweight vulnerability
scanner for web apps, Wfuzz can be a viable solution. ^[25]

Features of Wfuzz

• It can perform HEAD scans for faster resource disclosures and
  supports multiple encoding methods for payloads.
• Wfuzz comes with in-built support for HTTP proxies, SOCK,
  cookie fuzzing, time delays, and multi-threading.
• Users can save the output results in HTML files or export them
  to more powerful Linux vulnerability scanners.
• It offers excellent documentation for helping users get up and
  running as fast as possible.

Download Wfuzz^[26]

13. OSQuery

---

OSQuery is a modern-day system’s application that can be used
for instrumenting, monitoring, and analyzing changes in operating
systems. It is developed by the engineering team at Facebook and
relies on the SQL querying language for viewing changes in security
events.

Admins can use OSQuery for monitoring low-level system details
like running processes, network streams, kernel modules, hardware
changes, and even file hashes. The source code of this tool is
freely available at GitHub. So, developers can customize it for
adhering to enterprise requirements.

Features of OSQuery

• It exposes a modern, interactive console called osqueryi that
  allows users to try robust queries and explore system details.
• OSQuery comes with dozens of in-built tables that accelerate
  the diagnosis of system changes and performance issues.
• The powerful monitoring daemon osqueryd enables admins to
  schedule execution queries for large-scale infrastructures.
• OSQuery is built using modular codebases that guarantee
  top-notch performance and provides excellent documentation.

Download OSQuery^[27]

14. SonarQube

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SonarQube is one of the best open source security testing tools
for security professionals due to its rich feature set and
excellent performance. It is written using the Java programming
language and allows researchers to find some common threats to web
applications.

SonarQube can detect cross-site scripting vulnerabilities,
Denial of Service (DOS) attacks, and SQL injections, among others.
It can review websites for coding problems and integrates well with
tools like Jenkins^[28]. Overall, it is a
helpful tool for both security practitioners and web app
developers.

Features of SonarQube

• SonarQube can find hard-to-catch logical errors in web
  applications using robust static code analysis rules.
• Although written in Java, it can review apps written in more
  than twenty-five different programming languages.
• It can also be used for reviewing project repos and integrates
  easily with platforms like GitHub and Azure DevOps.
• SonarQube offers several paid editions for enterprises and
  developers alongside its open-source version.

Download SonarQube^[29]

15. Snort

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Snort is a powerful intrusion detection system that is currently
being maintained by Cisco. It allows security testers to capture
and analyze network traffic in real-time. It can detect several
types of web vulnerabilities, including but not limited to stealth
scans, semantic URL attacks, buffer overflows, and OS
fingerprinting. It offers excellent documentation for people who
are new to packet analyzing in general. So you can easily set it up
and start testing for network flaws.

Features of Snort

• Snort can be configured in three different modes, as a sniffer,
  packet logger, or network intrusion detection mechanism.
• It comes under the permissive GNU GPL license, so developers
  can easily add their own modifications to this software.
• Snort integrates perfectly with several third-party reporting
  and analysis tools, including BASE, Snorby, and Sguil.
• Cisco rolls out newer features and bug fixes for this intrusion
  detection system pretty often.

Download Snort^[30]

16. VeraCrypt

---

VeraCrypt is certainly one of the best open source security
tools for protecting sensitive data. It’s an open-source disc
encryption platform that allows users to encrypt their Linux partitions^[31] on the fly. Like
CipherShed, it is also a fork of the now-discontinued TrueCrypt
project.

VeraCrypt improves the performance issues faced by many
encryption software by developing the runtime using C, C++, and
Assembly languages. Moreover, it is entirely cross-platform. So,
you can use this tool on all of your machines without facing
compatibility issues.

Features of VeraCrypt

• VeraCrypt works by creating virtual encrypted discs which can
  be mounted normally on the Linux file system.
• It has in-built support for parallelization and pipelining,
  which makes sure disc operations are not slowed down.
• VeraCrypt provides some extremely advanced security features
  like hidden volumes and hidden operating systems.
• It offers several encryption formats, including transparent
  encryption, automatic encryption, and real-time encryption.

Download VeraCrypt^[32]

17. Moloch

---

Moloch is one of the most promising open source security testing
tools in recent times. It is a robust platform that facilitates the
capturing of TCP/IP packets and enables users to manage these
packets from a conventional database management
system^[33]. This open-source
project has been gaining popularity among many testers due to its
simplistic approach to mitigate common network threats. Moloch also
offers extensive, high-quality documentation for helping people get
started with this application.

Features of Moloch

• Moloch is extremely scalable and can be deployed on enterprise
  clusters that tackle multiple gigabits of traffic per second.
• It exposes a robust set of APIs that makes it easy to integrate
  Moloch with other open source security tools at ease.
• Admins can easily export their search results as PCAP or CSV
  documents using the centralized GUI interface.
• Moloch is entirely cross-platform and offers pre-built binaries
  for several Linux distributions^[34], including Ubuntu.

Download Moloch^[35]

18. Aircrack-ng

---

Aircrack-ng is the de-facto software suite used by hackers to
bypass wireless network authentication. It is a collection of open
source security tools, which include a sniffer, password cracker,
and analysis tools, among others. Aircrack-ng allows users to crack
WEP and WPA/WPA-2 credentials using several methods such as
statistical analysis and dictionary attacks. As with other security
tools, a lot of professionals also use Aircrack-ng for checking the
integrity of wireless networks.

Features of Aircrack-ng

• It supports several types of network attacks, including replay
  attacks, packet injection, de-authentication, and more.
• All tools provided by Aircrack-ng is controlled through a
  versatile command-line interface which supports heavy
  scripting.
• Aircrack-ng is readily available on most Linux distributions
  and is also fairly easy to compile from the source.
• The open-source codebase of this application suite makes it
  easy to inspect and add newer features.

Download Aircrack-ng^[36]

19. Tcpdump

---

Tcpdump is a simple but extremely powerful packet sniffer and
network analyzer for professional penetration testers. Its
effectiveness is proven in the industry, and it remains the go-to
choice for many when it comes to dissecting captured network
packets. This multi-platform tool has a cult following due to its
illustrious history and has motivated the development of many
modern-day sniffers like Wireshark. If you are an open-source
developer interested in the field of network study, you can learn a
lot using this tool.

Features of Tcpdump

• Tcpdump is a command-line tool that can be easily scripted
  using Linux shell scripting^[37] and other programming
  languages.
• Users can import pre-stored packets and display them in several
  formats, including HEX and ASCII, among others.
• There are many highly regarded documentation available for this
  packet sniffer, including entire books and Linux manuals.
• You can see the source code for a closer inspection of how
  Tcpdump works and may even contribute to its development.

Download Tcpdump^[38]

20. SQLMap

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SQLMap is an excellent open-source tool that allows admins to
search for SQL injection vulnerabilities in their websites and
applications. This free but powerful application provides a robust
testing engine that can find several types of SQL vulnerabilities,
including time-based, error-based, and boolean-based blinds, among
others.

Admins can easily dump tables to perform close inspections of
data. Additionally, the freely available codebase of this Linux
vulnerability scanner makes sure third-party developers can add
extra functionalities if they want.

Features of SQLMap

• SQLMap supports almost every major DBMSs including, MySQL,
  Oracle Database, MsSQL, Firebird, MariaDB, IRIS, and IBM DB2.
• It is a command-line tool with support for automatic password
  recognition, standard authentication, and dictionary attacks.
• SQLMap can be used to escalate database privileges via
  connecting to the Meterpreter payload of the Metasploit
  framework.
• This open-source application offers excellent documentation in
  the form of manuals, videos, and robust issue tracking tools.

Download SQLMap^[39]

21. Zeek

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Zeek is a compelling network analysis framework that has been
around for a long time. This intrusion detection mechanism was
originally known as Bro. It is one of the best open source
security tools^[40] for exploring anomalies
in personal or enterprise networks. Zeek works by capturing logs of
all network activities instead of relying on signatures like many
traditional IDS tools. Security testers can analyze this data by
manually reviewing them or through a Security and Information Event
Management (SIEM) system.

Features of Zeek

• Zeek is suitable for testing large-scale enterprise
  infrastructures due to its flexible and highly adaptable feature
  set.
• It offers an in-depth insight into the network under
  observation using high-level semantic analysis techniques.
• A large number of pre-built add-ons make it easy to add extra
  functionalities to this network analysis software.
• Zeek offers multiple builds for enterprises and developers,
  including an LTS release, feature release, and a dev version.

Download Zeek^[41]

22. Kali Linux

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Many people agree that Kali Linux^[42] is arguably one of the
best open source security testing tools for professionals. It is a
Debian-based Linux distribution that comes with all the essential
tools required in modern penetration testing. This is why a lot of
malicious hackers use Kali as their base system. No matter whether
you’re a certified professional or a starting security enthusiast,
mastery over Kali Linux will help you explore uncharted territories
quite easily.

Features of Kali Linux

• Kali Linux is available on a wide range of platforms, including
  ARM-based systems and the VMware virtual machine.
• Users can create live installations based on personal
  preferences and use several encryption mechanisms for
  protection.
• It allows testers to build custom penetration testing
  environments by choosing from a large collection of
  Metapackages.
• You can even run Kali on Android-based smartphones using the
  Linux Deploy^[43] application and chroot
  the environment if you want.

Download Kali Linux^[44]

23. GRR – Google Rapid
Response

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GRR or Google Rapid Response is a compelling incident response
framework developed by Google for maintaining live forensic
analysis jobs from a remote environment. It consists of a server
and client written in Python. The client or agent portion is
deployed on the target systems, and they are managed through the
server. It is a fully open-source project so you can add custom
features based on personal requirements very easily.

Features of GRR

• Google Rapid Response is entirely cross-platform and runs
  smoothly on Linux, FreeBSD, OS X, and Windows systems.
• It utilizes the YARA library for analyzing remote memory and
  provides access to OS-level details and the filesystem.
• Admins can effectively monitor remote clients for CPU usage,
  memory details, I/O usage, and many more.
• GRR is fully equipped for handling modern security incidents
  and allows automatic infrastructure management.

Download GRR^[45]

24. Grabber

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Grabber is a lightweight and portable Linux vulnerability
scanner for websites, forums, and applications. It is one of the
most useful open source security testing tools for assessing
personal web apps. Since Grabber is extremely lightweight, it
doesn’t offer any GUI interface.

However, controlling the application is quite straightforward,
and even beginners can test their applications using it. Overall,
it is a pretty decent choice for starting security enthusiasts and
app developers who’re looking for portable testing tools.

Features of Grabber

• Grabber can be used for simple AJAX verifications, cross-site
  scripting, and SQL injection attacks.
• This open source testing tool is written using Python and is
  very easy to extend or customize.
• You can use Grabber to check logical flaws in JavaScript-based
  applications very easily.
• Grabber creates a simple but useful stats analysis file
  highlighting its findings and major details.

Download Grabber ^[46]

25. Arachni

---

Arachni is a feature-rich, modular web application testing
framework written in Ruby. Security professionals can use it to
perform a wide range of tasks. It is quite simple to use but does
not lack in power itself. Moreover, the modular nature of this
tool allows users to integrate it easily with other open source
security testing tools like Metasploit. Since the source code of
this software is free to access and modify, third-part devs can add
newer functionalities without any restrictions.

Features of Arachni

• Arachni comes with a nice and intuitive graphical user
  interface, which makes it very easy to manage.
• It exposes a robust set of REST APIs that makes integration
  easier for open source developers.
• Arachni offers multiple deployment options, including
  distributed platforms and personal servers.
• It can be used for checking cross-site scripting, SQL
  injections, code injections, and file inclusion variants.

Download Arachni^[47]

Ending Thoughts

---

As we continue to rely on software, security has become more
important than ever. Thankfully, a large number of open source
security tools make it easy for professionals to inspect
vulnerabilities and allow developers to patch them before someone
exploits them. Our editors have outlined some of the most widely
used testing tools for our users in this guide.

No matter whether you’re a professional tester or a mere
enthusiast, having a knowledge of these tools will help you
mitigate many security flaws in the future. Hopefully, this guide
provided you the essentials you were looking for. Let us know your
thoughts in the comment section below.