For what it is worth, I have found that the STUN protocol is also an option for discovering this sort of information. There are lists of public stun servers out there [0]. Finding a client is a little more difficult than just using curl, I grant, but not impossible.
Awesome to see what other people have been doing. I have been getting more familiar with common-lisp and emacs / slime. Specifically using those tools to build a website to track the books that I have read, with the reviews and ratings that I've given them, so my sister and I can keep track of each other's reading lists.
Sort of like goodreads minus the blatant marketing.
[0]: https://gist.github.com/mondain/b0ec1cf5f60ae726202e