SMUX - session management protocol

Today, I got a question about SMUX. After answering the question, I decided to blog about it so you all can also become familiar with SMUX.

What is SMUX?
In short, SMUX is a session management protocol. SMUX separates the underlying transport from the upper level application protocols. According to W3C, SMUX aims to

ease transitions to future Web protocols, and communications of client applets using private protocols with servers over the same TCP connpcection as the HTTP conversation

For more information about SMUX, read the SMUX protocol specification at W3.org

You can see whether SMUX is on your server running by invoking

nmap -p 1-65535 localhost

Abbreviated output:

199/tcp open smux