You don't have to get the base port on each try, you can just re-use the previous result. I achieved this by simply storing them on the global scope and only keeping the "last" and "before last" port numbers.

https://gist.github.com/38c0430b5084f8442858 for my entire implementation.

Ah, of course - I did read through your code (obviously not carefully enough). How do you get down to 2400 requests though?

Edit: saw the answers above - it's 2400 average case, not worst case.