Testing your firewall online

June 2017




To test if your Firewall is active and running efficiently:

Online test




Here are the results:

If attempts to connect to your PC have failed, then it simply means that your Firewall is doing is job.
  • Common ports: it will check the ports if this result is green it means that your ports are invisible, if they are of a different color please check the configuration of your firewall. (If everything is green it means you are invisible: you do not exist for hackers).
  • All services ports: this will scan all your ports from 1 to 1056 and inform you whether your firewall protects well. **As below:

  • Color Code:
    • Green: the port is invisible
    • Blue: the port is closed, but it is not invisible
    • Red: the port is OPEN! Please immediately configure your firewall, as any hacker can enter without worries!

Test your port locally (using a software)

  • There exist software to run on your computer even to test the ports (like "local port scan").
  • The reliability of the software is almost zero, because they will not check which interface ports are open (localhost, external IP, or all interfaces).
  • Only a test carried out by external software to your computer (such as grc.com) are to be considered.

Online tests are not 100% reliable

  • Online test are not guaranteed to be 100% efficient.
  • There are indeed techniques such as Port Knocking and Single Packet Authorization, which can open ports in a firewall without this being visible in these tests.
  • (That said, if tests such as grc.com tell you that your ports are closed, you can be confident more than 99%.)

Additional Information


Some softwares can help to test the firewall.
  • Here are the latest information I have gathered about the subject:
  • Once the firewall software being tested is installed, it is configured with the highest-available protection settings. The computer is connected to a closed network, with the only one other system on the network being the one we use to send the port-attacking commands to the computer.
  • Nmap software's port-attacking commands are used to probe all 65,535 ports of a system. A detailed report is generated for each command, which reveals the status of each port as Open, Closed, Filtered, Unfiltered, or Stealth. Stealth is the best possible status and indicates that a firewall is working well.

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Published by jak58. Latest update on August 15, 2011 at 11:41 AM by jak58.
This document, titled "Testing your firewall online," is available under the Creative Commons license. Any copy, reuse, or modification of the content should be sufficiently credited to CCM (ccm.net).