[China] Monitoring dynamic obfs4 bridges
Inspired by #40054 (closed), let's use a ticket to track when we are seeing that these bridges are blocked.
We have two codenames for these bridges, Cobalt and Zinc. The current bridges can be found with these queries:
- https://metrics.torproject.org/rs.html#search/Sr2Zinc%20type:bridge%20running:true
- https://metrics.torproject.org/rs.html#search/Sr2Cobalt%20type:bridge%20running:true
(Obviously these search by nickname, so it is entirely possible for someone to start spoofing bridges here.)
These bridges are distributed by moat and so when they are blocked, we will simply turn them off and deploy new bridges that will automatically be distributed by moat. All we need to coordinate here is the reachability checks. It would be good if we can do these at least weekly.