Have you ever thought: Gosh, why isn't there a regularly updated, comprehensive list of publicly available STUN servers?
Well, this is it. A list of online STUN servers, refreshed hourly.
Hardcode this link valid_hosts.txt into your application, and use it anytime you need a fresh list of online STUN servers.
Or, if you don't want to rely on DNS resolution, use valid_ipv4s.txt for IPv4, and valid_ipv6s.txt for IPv6 addresses.
Well, not exactly. Hard-coding of links which were never meant to be hard-coded is bad. Here the situation is different. Since I recommend that users hard-code the links to the few specific files, I'll avoid doing anything that would make the link invalid (e.g. I won't change the name of the file, name of the repository, my Github username, etc.).
Feel free to open an issue and let's discuss your specific needs.
Hourly, you can see the timestamp of the last check in the commit message.
As long as the server correctly responds to an RFC5389 BINDING request, it is judged as healthy.
This is enough to establish the NAT mapping of a given socket.
Noteworthy: the server does not need to respond with an alternate IP address to be judged as healthy. This can be a problem if you need a server with full RFC5389/5780 NAT testing (endpoint mapping and filtering modes) capability.
If you need a list of servers that support RFC5389/5780 NAT testing, open an issue.
IP versions 4 and 6. UDP only. If you need a list of TCP servers, open an issue.
Lazy/inconsiderate devs will tend to just grab the top-most link from the list (and TBF, can we blame them?). By shuffling the list, I ensure that we don't end up spamming the same host forever.
The list is in candidates.txt. Feel free to create a PR adding more servers, or just open an issue and list them there.
Open an issue, and it will be removed from the automated checks within 24 hours.