Building Secure Software: How to Avoid Security Problems the Right Way

16. Through the Firewall

Something there is that doesn’t love a wall,That wants it down.

—ROBERT FROSTMENDING WALL

Sometimes even when security isn’t a concern for a product, it can still be a nuisance. One technology in particular is adept at causing developers of Internet applications grief—the firewall. Generally, any time your application needs to run over a network, and installs network-aware code on a client’s machine, you need to consider the impact of different firewall strategies.

A common goal of system administrators is to protect naïve users from running untrusted code. A common goal of the application developer is to allow end users who want to run any application to do so. Although we certainly understand and respect the wishes ...