Qmail: a case study in security patterns

This morning I attended a breakfast seminar hosted by BrightSpot and featuring a lively Ralph Johnson.

In the development world we have "design patterns", basically smart, experienced people helping us new guys out by sharing what works and what doesn't. In working towards making some security design patterns, Mr. Johnson and some of his students studied the notoriously secure application Qmail.

The short version: You can either try to build the perfect (unbreakable) application, or build your application accepting the fact that attacks happen. Qmail is designed to minimize the effect a break in one part has on any other parts. Split your application into multiple processes with each one being as simple and having the least permissions possible.

Oh, and at the end I won a signed copy of his book in a draw.