Uh-oh. Java's sort of mandatory for this one.

No Java support was detected in your browser, or you forgot to grant it sufficient security privileges.

The bottom line is, you need Java 1.4 or later, and you also need to OK the security dialog so the signed code can run. Signed code is needed for a variety of reasons - none of which entails running nasty stuff on your computer.

If you're curious, you can read more about how this thing works here.

This is what you're missing out on: traceroute.png

To get Java for your browser start at http://java.com/en/download/index.jsp.