Firewall testing makes sure that the hardware firewall does its job. While hooked up on the Internet, your computer may have thousands of ports open. If these ports are open, cybercriminals may try to put a bot on your machine and turn it into a zombie or part of a botnet.

There are many online firewall test sites, but you must be quite skeptical about which of them to reply on. Do not put your entire trust on the testing site given by a company that wants to sell you a hardware firewall. Once your firewall goes live, firewall testing is needed to make sure that it is serving its purpose and that you have configured it correctly.

What are hardware firewalls? Hardware firewalls work in the same way as routers but with more features. While many routers today come with a built-in firewall, true hardware firewalls have more functions. They are positioned in between the router and the modem. They work as a barrier between the internal network and the Internet where external security threats may come from. These threats include malicious software (malware) like worms, viruses, trojan horses, and spyware. Hardware firewalls protect the entire network by filtering packets of data.

For a glimpse of some of the popular hardware firewalls available in the market today, check out our Best Hardware Firewalls Buyers Guide.


Free Firewall Testing Tools

Firewall testing allows you to know that your hardware firewall works to protect your network. Firewall testing tools may come as proprietary or brand-exclusive. Vendors provide these tools so users must communicate with the firewall provider if they need them. Firewall testing checklist with these proprietary tools focus on efficacy and look at specific parameters like antimalware, application identification, and intrusion prevention. On the other hand, there are firewall testing utilities that users can download online for free. Here are some of them.

1. Nessus

nessus vulnerability assessment solution

Considered as one of the best open-source security scanning utility, Nessus not only inspects the firewall of a host but also detects known application-based vulnerabilities. Users recommend Nessus for periodic or scheduled scans which can be done weekly or monthly. The utility automatically updates its plugins, providing users real-time information on emerging malware and vulnerabilities.


2. Nmap


Short for Network Mapper, Nmap free open-source utility for network discovery and security auditing has gained the trust of many systems and network administrators over the years. Some tasks that users found useful on Nmap include network inventory, service upgrade management, and service uptime monitoring. Nmap utilizes raw IP packets to identify the hosts present on the network, the applications the hosts offer, their operating systems, the active firewalls, and several other parameters. Nmap can be used on both single hosts and large networks.


3. Netcat

Netcat free networking utility reads and writes data across network connections by using the TCP/IP protocol. This reliable backend tool can be used directly by other programs and scripts. Netcat provides access to these main features like outbound and inbound connections to or from any ports; tunneling mode; built-in port-scanning capabilities with randomizer; buffered send-mode; hexdump of transmitted and received data; and optional RFC854 telnet codes parser and responder.


4. Wireshark


Claiming as the world’s widely-used network protocol analyzer, Wireshark allows you to see what’s going on on your network at the microscopic level. The utility is considered as a standard among many commercial and non-profit organizations, government agencies, and educational institutions. Some of its features include deep inspection of protocols, live capture and offline analysis, multi-platform compatibility, rich VoIP analysis, live data readability through any connectivity, and decryption support for many protocols.


Free Online Firewall Testing Sites

Many free firewall testing sites are available on the Internet as well. Most of these open-source alternatives do performance evaluation while connected to the Internet and do not require software installation. Some setups consist of testbed checked against a null device like a router with the parameters set to simulate a real-world scenario.

1. Audit My PC Security

audit my pc

Audit My PC ( started as a site in 2000, offering vulnerability assessment, privacy test, research, and security information to users – 100% free of charge. With the objective of providing a better understanding of security and in-depth web-based programming, the site allows users to perform remote security scans without limits or the hassle of registration.

Audit My PC’s site has the ability to see if your device has open ports that cybercriminals can exploit to access your files, camera, and microphone. Visitors who own websites can also take advantage of the site’s Website Audit tool to identify weak points that need improvement.

Audit My PC’s firewall test checks your computer for ports that are usually left open and can be exploited by cybercriminals. The firewall test also looks for ports known to be utilized by viruses that may be present in your system.


2. ShieldsUP

shields up

One of these tools that you can include in your firewall testing procedures is ShieldsUP. Available for download on the Gibson Research website (, ShieldsUP enables you to do firewall port testing. Firewall performance testing consists of various scans. With ShieldsUP, you can do some of these scans. ShieldsUP’s firewall testing checklist consists of the following:

All Ports & Services Test

With this test, all ports ranging from 0 to 1056 go through scanning to see if they are open (red), closed (blue), or in stealth mode (green). If a port appears red, you should check what is running on that port. Check if something is not on your firewall rules list. If not, malware might be running on your computer and it may have already become part of a botnet. In this case, you should run an Internet security suite with a software firewall to scan hidden malware services.

Browser Disclosure Test

This test lets your Internet browser reveal the status of your system. It reveals vulnerabilities like browser plugins can make your machine open to attacks and hacks. It shows that security theft happens even if you are not browsing the Internet, interacting on social media, or downloading a file.

Common Ports Test

This test investigates the by popular services like FTP, NetBIOS, Telnet, and many others. The test confirms whether the stealth mode of your computer or router works or not.

File-Sharing Test

With this test, users can identify the common ports linked to vulnerable sharing ports and services. If these ports and services operate, it means that your computer might be running a hidden file server. This vulnerability opens your system to attacks coming from hackers to access your file system.

Messenger Spam Test

This test tries to send a Microsoft Windows Messenger test message to your computer. It allows you to see if your firewall works to block the service which can be manipulated by spammers to send you messages. Applicable to Windows users only, Linux and macOS can skip this test.


3. HackerWatch


HackerWatch’s online anti-hacker community ( allows Internet users to report and share information to block and identify existing and emerging cybersecurity threats and unwanted traffic. With new threats appearing every month, Internet users must not stop utilizing methods to protect one of the most important assets stored on their devices – their personal information.

While software firewalls are crucial, HackerWatch’s mix of community participation and technology through McAfee Personal Firewall helps in analyzing corporate and individual data. The site reveals attack patterns and hacking attempts. HackerWatch notifies authorities and Internet service providers as soon as a trend is observed.

HackerWatch offers two probing methods to visitors:

Simple Probe

This probe method simply generates some event traffic on your device to test the event notification dialog and see some events in the log.

Port Scan

This probe employs HackerWatch’s server to test a list of common ports on your device and determine if it can get a connection to them.


4. SecuritySpace

Security Space

Backed by E-Soft Inc., SecuritySpace ( provides Internet security and online services specializing in vulnerability assessment, network security auditing, network monitoring and notification, DNS hosting, and research and analytics on network technology usage. While the site is commercial in nature, it offers a free scan similar to Nessus, an open-source security scanner. It not only checks the firewall of a host but also scans for known application vulnerabilities.