Custom CCA as the Cause of IP Blocking #1447
Description
A few months ago, my Hysteria2 server with obfs was blocked by the Iranian gfw, and I was very surprised because, based on my tests, the firewall does not treat UDP-based protocols as strictly as TCP. Normally, UDP traffic gets disrupted, but the server IP itself is not blocked.
During this time, I ran tests with other UDP-based protocols such as mieru and xhttp-quic with udp-noise, and I noticed that this blocking only happens with Hysteria. After searching on Google, I came across this paper, which led me to suspect that the IP blocking of my Hysteria servers might be caused by the use of a custom CCA in Hysteria, as mentioned in the article