In this chapter we looked at how to implement a positive security model using a four-step process. We learned about the pros and cons for this sort of security model and how to assess whether the model is suitable for a particular web application. We then went on to implement the positive security model for the forum software YaBB.
We saw how to analyze user actions to find out exactly what should be allowed, and we learned how to use SecMarker in conjunction with the skipAfter directive to control the execution path for the rules. Putting all this together, we ended up with a ruleset implementing the security model. Finally, we learned about some alternative approaches that could have been used in developing the ruleset and the importance of keeping the model up to date so that the web application doesn't stop working when new releases of it are installed.
