[jbeckham]

Back in the late 90's and early 2000's, there were a set of hacking challenges called the Zebulun Challenges hosted by the site CyberArmy. For the 7th or 8th challenge (Lt. Kernel to Kernel), you had to find a proxy or have an rDNS for your IP that resolved to a .su domain in order to proceed into the simulated system you were trying to hack into.

[dsl]

Which isn't that hard. You just update your reverse DNS.

I assume for a later challenge they actually checked the forward DNS matched. :)

[jbeckham]

In the late 90's with dial-up connections, most ISPs would not do this, hence the search for .su proxies. Today, it is much easier when you can spin up a VM in the cloud and control DNS entries.