Firewall: Using an Internet Port Scanner

Windows Firewall can protect your computer from many types of online attacks. Although it may not protect you from getting viruses or malware; it can protect your system from running an application that has not been specifically allowed by you as the user. Some may think that firewalls are a nuisance but it is a necessity especially when it comes to the security of your computer.

If you are not careful you may end up blocking an important service or port so you should always configure Windows Firewall through the Firewall Wizard. At the same time many users will inadvertently open a port or service to the Internet allowing for attacks. When troubleshooting network connectivity issues with Windows Firewall your first step should be to disable it completely to see if it resolves your problem. Ideally you should never leave this disabled because this leaves your computers attack surface much bigger. If you are behind a hardware firewall then your attack surface is lowered but your system is not fully protected. If the issue is resolved by disabling Windows Firewall completely then you will need to review all the firewall rules.

Within Windows Firewall with Advanced Settings you can also check which ports, programs or services are being allowed and denied. It also lists all Inbound and Outbound rules. The New Rule Wizard will allow you to create allow or deny a program, port, using a predefined rule or a custom rule. Using the Custom Rule Wizard will allow you to get to a granular level which will allow you to create a rule based off a program and a port. These are a few rules that you should check for because there might just be a type of malware that will create false firewall rules that block Internet Explorer from accessing both HTTP (80) and HTTPS (443) ports. Keeping a keen eye out for these types of rules is very important because they can be easily overlooked.

By using these tools it will allow you to better troubleshoot your network connectivity issues.