Find Proxy Authentication bugs with Fiddler

Over on my other blog, I just posted an article showing how you can use Fiddler to find bugs in applications that don’t expect authenticating proxies.

.NET HttpWebRequests and Expect: 100-continue

Recently, a colleague asked me to look at a network capture in which a .NET client application’s communication with a web service was not meeting their performance goals. In particular, he noted that this was primarily a problem on high-latency networks; each of the dozens of requests took hundreds of milliseconds, even when existing connections…