How do Firewalls work

If you are a frequent Internet user you have probably come across the term "Firewall". Sometimes you first learn about a firewall when you can't connect to certain hosts or P2P networks, because your connection is blocked.

Nowadays, almost all antivirus and Internet security applications come with the firewall feature included. A few years ago software vendors rarely put firewall into one package with the antivirus because they wanted you to buy separate products, but this trend has been abandoned due to the stiff market competition and neatly every single antivirus program now has a firewall.

Firewalls work in a way that they filter incoming and outgoing Internet traffic and only pass the data packets that are eligible to pass. In other words, if you configure your firewall to block traffic on certain TCP/UDP ports, you won't be able to connect to a remote host providing services on that port.

For example if you are a frequent eMule or Torrent user, your connection to other peers may not work if your firewall is configured to block ports responsible for P2P transactions. These settings can be, however, easily changed and adjusted to your current needs. Every personal and home use firewall software, also those included in popular antivirus applications, give you the ability to configure connections. Please refer to your Internet security software manual for details on how to properly configure your firewall.

But firewalls aren't only designed for making your p2p file exchange a bit more complicated. In fact, there are plenty of good reasons, why you should have a properly configured firewall enabled at all times. One of the reasons is hackers.