Unclear how script discovers quic versions

[high3eam]

Since my server for example uses quic, too, its used versions are not recognized by this tool.
Already tried to adjust the alternative services header to be like the one from google, still doesn't work.

This tool sends a dummy packet so the quic server should respond with its offered negotiationable versions, is r.g. the caddy web server able to respond to such a request ?

Thanks!

[povilasb]

Don't know how I missed this issue, sorry!

Indeed, Google has changed something with their latest QUIC version and the tool won't work anymore :/
Yes it would simply send a dummy packet with some invalid version and expect version negotiation packet which would contain all versions supported by the server side.
Another person has contacted me about these changes and maybe we'll come up with the solution shortly. Stay tuned :)

[tec1987]

See https://quicwg.org/base-drafts/draft-ietf-quic-transport.html#rfc.appendix.B.4

'''Initial packets from clients need to be padded to 1200 unless a Handshake packet is sent as well (#2522, #2523)