Making your Computer Accessible from the Public Internet

Set Up Your Firewall So It Does Not Block Connections

Below is a text transcription of the "Firewall Configuration" video that is part of the Making your Computer Accessible from the Public Internet tutorial series for troubleshooting remote access to server-based applications.

Configuring your system and third-party firewalls

Firewalls are great for protecting computers against harmful attacks, but can also hold up the connections you DO want to get through to your computer. There are basically three places firewalls might exist in your network— the operating system firewall, the router's firewall, and any third party security software you might have installed on your computer. If you are having trouble allowing users on the outside Internet to connect to your computer, you should check that each firewall has an exception for the application you are trying to make accessible over the Internet.

If you find a firewall is blocking your application, fixing the situation is a matter of creating a rule or exception for the application. You'll need to know which port the application communicates on, and if a UDP or TCP protocol is being used. This can usually be found in the settings, options, or manual information within the application. The same port number must be used throughout your computer and the network for each individual program, or the proper connections will not be made.

Stock Operating System Firewalls:

Your computer most likely came with a firewall installed on the operating system. Most OS firewalls work on an application level, allowing certain applications to have complete access to the Internet. Some firewalls need to know the port an application is using in order to allow it access to the Internet. If the application you are using needs to connect to the internet, you can create a rule for it through your OS firewall. Many applications automatically create a rule for themselves in the OS firewall upon installation, but you should still check the rule has been made, unless you are not using your computer's stock firewall.

Windows XP, Vista, and 7

Each version of Windows has a slightly different path to reach the firewall settings. From the Control Panel, look for the Security Center, Network and Internet, or System Security, and click the link for Windows Firewall. In the window that appears, you'll want to click the link for allowing a program through the Windows Firewall, and then click on the Exceptions tab if it's available.

You'll see a list of applications and programs. Check to make sure that your application is on the list, and that it's checked. If it is missing from the list, the firewall is blocking inbound connections and you need to create an exception. Add the application to the exceptions list by clicking the 'Add program…' button and choosing the application from the list or browsing to its location, the click 'OK.' Now, from the exceptions list, make sure the application is checked, select it, and click the 'Add port…' button. In the Name field, enter the application name, enter the port number your application uses, and select TCP or UDP protocol. Click OK to save the changes. The exception has been created.

Mac OS X 10.4, 10.5

You can add an exception for a specific application in the firewall for on a Mac. Finding the firewall settings varies on which operating system you're using.

Most Mac users will select System Preferences from the Apple menu, click the View tab, and select either Sharing or Security, and then click the Firewall tab. From here, instructions will vary. You'll want to add the application to the firewall list, along with which type of connection on which port it uses. This can be done by clicking 'New,' or by choosing to 'set access for specific applications' and clicking the plus sign to add the application.

More specific instructions for your operating system can be found on the Internet. Try searching your operating system along with the keywords firewall and port.

Third–Party Firewalls, or Personal Firewalls:

Many computer users opt to install a firewall on their computer in addition to the stock OS firewall. Third–party firewalls can block traffic based either by application, or by specific ports, depending on how they operate.

Checking rules or exceptions varies from firewall to firewall. Check your application's documentation, or search for resources online by searching the firewall's website and checking their support files or contacting them directly for help.

Your Router's Firewall

The first two firewall examples were of software firewalls. They are programs installed on the computer they are protecting. Hardware firewalls are outside your computer, and the most common example is a router. Most people use NAT routers in their homes or businesses. A NAT router, or Network Address Translator router, allows a network of computers and devices to share one public IP address for outbound communication. A side benefit to how NAT routers naturally work is that they also act as a firewall to all the computers and devices on a network because they block unidentified incoming communication.

Configuring your router to allow connections from the outside Internet may be found under firewall settings on your router's software, or may be accomplished through port forwarding. For more information on configuring your router, view our router configuration and port forwarding tutorial.

Making your application visible to the outside Internet is a matter of making sure every element related to your Internet connection is in sync. In this tutorial, we've made sure that all your firewalls have rules or exceptions to allow your server–based application to be accessed from the public Internet. Hopefully, this has helped solve your connection problems. If not, try watching our other video tutorials addressing this issue. They cover topics such as port forwarding, STUN, and IP addresses. They can all be found at the address shown on your screen, along with additional resources to help you get up and running.