> Pretty much your only mainstream options today are QUIC and WireGuard, and only QUIC is intended to run in userspace. Not sure it fits your "mainstream" qual

> Pretty much your only mainstream options today are QUIC and WireGuard, and only QUIC is intended to run in userspace. Not sure it fits your "mainstream" qualification, but many projects ago I used Airhook to help create a userspace, application-layer('ish), multi-channel virtual network: http://airhook.ofb.net/ http://airhook.ofb.net/ (https://github.com/egnor/airhook https://github.com/egnor/airhook) Airhook is a relatively low-level library that handles framing and flow control; it's not a functional solution on its own. But that seems to be what you're getting at--something you can deeply integrate into your application, not a separate service. Though, I guess containers have sort of muddied that distinction.