[jeroenhd]

> - avoiding some badly behaved ‘middleware’ boxes between users and servers

Surely badly behaving middleboxes won't just ignore UDP traffic? If anything, they'd get confused about udp/443 and act up, forcing clients to fall back to normal TCP.

[zamadatix]

Your average middlebox will just NAT UDP (unless it's outright blocked by security policy) and move on. It's TCP where many middleboxes think they can "help" the congestion signaling, latch more deeply into the session information, or worse. Unencrypted protocols can have further interference under either TCP or UDP beyond this note.

QUIC is basically about taking all of the information middleboxes like to fuck with in TCP, putting it under the encryption layer, and packaging it back up in a UDP packet precisely so it's either just dropped or forwarded. In practice this (i.e. QUIC either being just dropped or left alone) has actually worked quite well.