On 12/26/22 00:55, John Selbie wrote:
Greetings,
I hope this is an appropriate mailing list to discuss a technical issue with Tor's Snowflake project. Please redirect me to the right place if not.
I am the original author and maintainer of the open source project, Stuntman. Stuntman is an implementation of the STUN protocol, which includes the STUN server. More details at www.stunprotocol.org http://www.stunprotocol.org. In short, a STUN server helps bootstream direct "p2p" connections such as WebRTC sessions or similar VOIP scenarios by allowing internet devices to self-discover their own public IP address and obtain a (UDP) port for communicating with another node.
I also run a public instance of a STUN server with the code at stun.stunprotocol.org http://stun.stunprotocol.org. It's been up and running for about 10 years now. It's hosted on AWS. In recent years, the hosting bills for this server have started to get on the high side, even with reserved instances. The number of STUN queries it processes per day is now on the order of hundreds of millions. The stunprotocol.org http://stunprotocol.org domain receives nearly a million DNS queries on Route 53 daily. What used to cost a trivial number of dollars to run is now starting to reach $1000 in annual service costs. This isn't paid for by a corporation or well funded internet organization. I pay this out of my personal pocket.
It's been a mystery what has been driving the increasing traffic to the server - especially redundant requests from the same IPs. I was inspecting the DNS logs the other day and started to investigate the nodes sending out redundant DNS requests repetitively. Trying to understand why these nodes wouldn't leverage DNS caching. And to my surprise, one of the IPs was running a web server that presented a TOR landing page. That led me to discover this discussion online:
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowf...
And a quick inspection of the Snowflake code leads me to find that stun.stunprotocol.org http://stun.stunprotocol.org is the default STUN server for Snowflake proxy and listed throughout the documentation as well.
While the Snowflake project has good intentions, it doesn't appear to take my hosting costs into consideration. I'm hoping we can have a good discussion on the following:
- How many snowflake clients and proxies are active and how many STUN
requests are each generating towards stunprotocol.org http://stunprotocol.org? Do we think the entire worldwide usage of Snowflake could be responsible for millions of STUN queries to stunprotocol.org http://stunprotocol.org per day?
- Expected number of DNS queries (it's a 3-day TTL on these DNS
entries, so it blows my mind that there are so many redundant requests). Does Pion or any other part of the Snowflake code tend to go direct to the namespace server itself?
- Removing stun.stunprotocol.org http://stun.stunprotocol.org as
the default STUN server.
OR...
- Alternatively, I'm always open to accepting donations to help run
the service costs of stunprotocol.org http://stunprotocol.org. I'm definitely not getting rich running this thing.
Thanks, John Selbie
Hi John,
Thank you for reaching out. This is exactly the right place to discuss this. This was an oversight on my part not to reach out to you as the operator of our configured default STUN server and I'm very sorry for the unexpected increased costs. We can absolutely remove stunprotocol.org as the default.
First, to answer some of your questions:
1) I would definitely believe the amount of snowflake traffic to stunprotocol.org to be this high. We have over 100,000 proxies. According to recent metrics[0], there are around 8 million matches a day and therefore that many WebRTC ICE gathering requests coming from just the proxies. The clients use a randomized subset of configured STUN servers, so the number is slightly different but it's safe to say they are also generating a few million STUN queries to your server.
2) I'm not sure about the DNS queries. It also surprises me that there are this many, I'll open an issue to investigate why.
Now for immediate next steps. I've sent an email to people internally to start the process of looking into sending some funds your way for the costs. We might not get an answer until after everyone is back at work in January. In the meantime:
- I'd like to remove stunprotocol.org as the default STUN server for the proxies. The reason we added to our list in the first place was because it implements RFC 5780 which we are using on the client side to determine NAT matching and filtering types (thank you for this implementation BTW!). The proxies no longer use this however, so there's no reason we can't have them use any number of other public STUN servers.
- We can remove stunprotocol.org from the list of *default* client STUN servers and reserve it for a small subset of users instead. This would really cut down on the traffic, but keep it open as an option for clients in places that have blocked other industry STUN servers.
How does this sound to you?
Thanks again for all the work you've done on Stuntman and in running a public server. I'm glad you reached about this.
- Cecylia