Know your SCM_RIGHTS

This post introduces the concept and implementation of SCM_RIGHTS (Send/Receive Control Message - Rights) as a mechanism to share file descriptors between processes on Linux. It details how Cloudflare leveraged this to enable a Go process to selectively handle TLS 1.3 connections while an existing nginx process handled older TLS versions on the same port, contributing a specific technical solution to the challenge of managing distinct traffic handling for upgrades or new protocol adoption without service interruption.