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How to test your firewall online to see if it works

How to test your firewall online to see if it works

The Great Firewall of China, officially known as the Golden Shield project, uses a variety of methods to block foreign websites that the Chinese government doesn't like. The Chinese government does not publish a list of blocked sites, so it is not easy for foreigners to know whether your website is visible in China or not. However, there are several web-based tools that can quickly find it.

Free online firewall trial

A firewall is simply the first line of defense for the security of any system. As such, one should not rely solely on its ability to stop all potential threats floating around the Internet. All kinds of misfortunes can happen for which a firewall is as useful as hiding to cover a big explosion.

How to check if the firewall is working properly

Having a firewall installed but poorly configured is approximately equivalent to not having one and would be a potential danger since there are botnets or agents that constantly scan the network for open ports and unprotected services.

We are going to see how easy it is to test the effectiveness of our firewall in some online services and that they will be able to tell us in seconds if everything works as it should. They will tell us the status of the firewall ports and the response they send to the outside.

1. GRC Shields UP

You could say that Shields UP - from Gibson Research Corporation - has been my preferred firewall shopping service for years. This tool is accessible through the browser and allows you to discover vulnerabilities in 6 different areas:

  • file sharing
  • Common port scan
  • All service port scan (all)
  • messenger spam test
  • Browser header test
  • UPnP exposure test (analysis of exposure to vulnerability in this protocol)

Once we perform the port scan we will see a summary similar to this, where those colored in green are ports that do not report their status (they simply do not respond, the ideal case). They could also appear blue -closed- or red if they were open, the worst possible scenario.

For example, in the following image, we can determine that one of the ports preferred by hackers to attack -139, corresponding to the Windows Netbios service- is correctly secured and also does not send a response.

2. McAfee Hacker Watch

On the Hackerwatch website offered by McAfee we can also carry out several tests to check if the firewall is properly configured:

  • easy tracking
  • Port Analysis

The computer must be directly connected to the internet to receive notices from the tool. That is, if we are behind a proxy or NAT it will not work.

3. PC Flank – Advanced Port Scanner

This advanced port scanner is capable of testing open ports that could be used to attack us. We can choose several analysis techniques such as standard TCP or TCP SYN, in addition to being able to choose based on the ports:

  • Typical Port Scans
  • Scan ports vulnerable to Trojans
  • Analysis of all the ports of the equipment
  • 20 random ports
  • Etc

Stealth test The same website allows us to test the possible filtering of the status of the ports analyzed (known as Leak test) as in other services such as GRC. Is your team visible from outside the network?

4. SG Security Scan

SG security gives us the option to perform a remote port scan to detect vulnerabilities. This service uses techniques similar to real attacks to try to sneak through the firewall (so that alerts could be triggered in it).

Once the tests are finished -we can also choose the ports manually- we will see a summary with the results.

5. Open ports test

On the test develocidad website and specifically in its port verification section, we will be able to know its status, which ones respond and which ones do not.

Getting around the Great Firewall of China

An alternative solution to access restricted sites and bypass the Great China firewall test is to download and sign up for a VPN service before entering mainland China. Going to Hong Kong to download VPN apps is one option as Hong Kong still retains its original laws regarding internet accessibility. Otherwise, ask a friend located in another country to send the VPN installation file directly. There are also web browsers, such as Firefox and Opera that have built-in VPN functionality that can be enabled for private browsing.

Using VPNs, however, typically slows down downloading and accessibility by 30 percent or more. Faster VPN services are more expensive. One major drawback is that your location appears to be from a different country, and this can cause login issues, especially for certain apps and websites that track login locations for security purposes. Message timestamps are also affected due to time zone differences with the country where the VPN server is located. Therefore, whenever you connect to a VPN, a best practice is to use a country as the server location and then stick to it. Using the same country each time is important to prevent your account from being locked due to suspicious access from another location.

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