Firewalls are set up to protect computer networks. Originally, networks were just coupled together, in order to achieve connection. With the ability to reach networks all over the world, one started to denote this the Internet. When the Internet evolved, the focus of design was on connectivity, efficiency and reliability, but not on security. Gradually, the need to control the traffic gave rise to enhanced security features of the routers connecting the networks. In the 1990s this was no longer sufficient, because people were able to circumvent this simple barrier. Dedicated devices then developed into more advanced mechanisms. The concept of a digital firewall was born. Today a plethora of threats to a network challenge the firewall and organisations who are managing the firewall system. This thesis will go into the many tasks involved in managing a firewall system. We will look at challenges but also suggest solutions to some of the issues.