New Java applet analyses your network connection

The International Computer Science Institute (ICSI) at Berkeley is (according to their web site) an independent, non-profit, research institute, funded by the US Government. Part of ICSI is the Center for Internet Research which just released a network analysis tool, the ICSI Netalyzr.

According to their blog:

Our goal was to build a service that shows you in detail what's up with your network connection, whatever network you might find yourself in, whenever something is not working, or when you're simply curious. The numerous tests conducted by the Netalyzr include HTTP proxy discovery, HTTP caching behavior, NAT detection, TCP & UDP port filtering, DNS resolver behavior, IPv6 connectivity, connection latency, bandwidth, and buffer properties, and more.

 
The analysis of your network consists of many different tests and seems pretty thorough. The report, however, can be fairly techie. There are explanations of the various tests, but without a background in networking you may find the explanations too technical to be useful.

Results are color coded: red is a major abnormality, orange is a minor aberration, green results are good.

My network had a couple red problems. One test warned that my uplink buffering was rated at a "quite high" 1100 msec. Another test warned that OpenDNS was acting as a Man-in-the-Middle for Google.

I found the explanation of each problem unsatisfying (the test name is a clickable link). Neither provided a good understanding of the problem, its seriousness or what, if anything, to do about it. For example, the description of the buffering problem discussed buffer sizes but the problem was one of timing.

I very much doubt that OpenDNS is doing anything bad, but the explanation of their being an "intermediary" for www.google.com didn't seem to relate at all to the explanation of reverse lookups.

Netalyzr went live last week and is labelled as beta. To use it, all you need is a Java-enabled web browser, so it should work with Windows, Linux and Macs.

Netalyzr is certainly worth a try.

It's good to know that my "ISP's DNS resolver accepts additional (glue) records for nameservers located in subdomains of the queried domain."