Univention Bugzilla – Bug 57099
Veyon WebApiProxy connections last too long and may double the bandwidth usage
Last modified: 2024-03-01 11:44:23 CET
When a teacher uses the computer room and logs out or closes the module, the connection between the Veyon WebAPI proxy and the computers will stay alive for the UMC session time + 1 min. So by default 11 minutes. What can happen: 1. teacher1 logs and starts the watch page 2. After the class, teacher1 logs out 3. next class directly after: teacher2 logs in and takes over computer room 4. Now for 11 minutes, the bandwidth usage from web api proxy to the computers is _doubled_ as old and new connections are up. Of course, if teacher1 does not log out, it is not only for 11 minutes but as long as he keeps the computer room module session alive. Basic reproduction steps: 1. Have a working computer room setup 2. Create two teachers 3. Login with the first teacher, watch the room 4. Track the bandwidth usage, e.g. with `iftop` or the number of connections e.g. `lsof -i -P` 5. As soon as you login with teacher2 and take over the room, you should see doubled bandwidth and doubled connections for as long as the module sessions are alive
I think, an additional behaviour might multiply this problem: some customers create a room that is called "All computers" that obviously contains all computers. If the computer room module is opened, it tries to detect the room automatically and chooses the first one that matches according to the clients IP address. If a "All computers" room exists, this is usually the first room that matches, so a connection to all computers is established.