What is a Firewall?

Date posted: August 22, 2011

A firewall is a security solution that prevents other computers on the Internet or your network to connect to your computer.  A firewall protects your computer by not allowing any data connections from external systems in which you did not initiate the connection first.  An example of this would be if you try to access www.google.com, you are initiating the connection to the Google server, so as the data passes outbound through your firewall, your firewall will then take any data coming from the Google server and pass it along to your computer.  And if a Google server attempts to send data to your computer without you trying to access it first, then your firewall will block all of that data traffic.  So if you are at a Starbucks and using the public Internet connection, your Windows firewall is what prevents others at the Starbucks to make connections or try to break into your laptop.

There are two types of firewalls – software and hardware.  A hardware firewall is a physical device that will sit between your computer and the Internet.  In most cases your Internet router has a built-in firewall.   A software firewall resides on your computer and monitors the data passing through your wireless or Ethernet ports.  Typically hardware firewalls are Cisco, SonicWALL, Netgear, Linksys, and DLink.  Examples of software firewalls are Symantec 360 Protection and Windows’ built-in firewall.

So what if there was something that you wanted to share or host with others?  For example, what if you wanted to share files with another user on your office network or host a website to the Internet?  What you would be doing is placing firewall exceptions for only those hosted services, and then deny any other traffic besides those specific items.

More advanced firewalls can also scan and prevent viruses, spyware, and other malicious software.  And even more advanced firewalls have IPS (intrusion protection system).  IPSes not only blocks external attackers, but contain intelligence with how it will detect and scan, as well as advanced reporting tools.

If you have any additional questions on firewalls, please feel free to contact us.