While looking at the snowflake broker metrics for clues about the sudden drops in known proxy NAT types[0], I noticed that the broker metrics show a very large spike in client polls over the last day. I've attached a few graphs that show this, which probably won't have showed up in tor relay metrics yet.
One of the graphs is the usage of proxy capacity, which shows a rise in the number of client polls and a large drop in idle proxies. The other graph shows something similar, but for the pool of proxies available to clients with restrictive NATs. Here we see that the overwhelming majority of clients are being denied because all of the proxies are used.
To some extent, we expect this and have seen it in the past, particularly for the pool of proxies for clients with restrictive NATs. The pattern follows a natural day-long period, and the number of denied clients never gets so high that a client won't get a proxy after 2-3 tries. However, these attached graphs go back 48 hours and show how much bigger the spike in clients is over the last day. At the peak of the spike, there were 5x as many clients requesting snowflake proxies from the restrictive pool as we had proxies to match.
Perhaps this is a good time to push to get more proxies? It seems we could use proxies for both restrictive and unrestrictive NATs at this point.
Cecylia
[0] https://lists.torproject.org/pipermail/anti-censorship-alerts/2022-February/...
