Firewall Patterns

In this paper we provide three firewall patterns. The firewall pattern describes how access to internal networks can be restricted in general. It shows the basic problems and indicates a general solution. The other two patterns are more specific variants which are usually used in order to implement access control at the network border. This paper is also an experiment of understanding what it means to specialize security patterns and how we can cope with this presenting them in a useful and joyful way to the reader. The patterns themselves are part of an initiative to integrate known security-related patterns into an overall security pattern system.