Multiplexing allows a single SSH connection to be shared by multiple sessions. The connection could be set to persist for a set time and then reused for fast reconnection to the server.

Related: How to speed up SSH authentication

Sharing SSH sessions in a single connection via multiplexing could be configured in the user's SSH client configuration file.

Steps to share and reuse SSH connection via multiplexing:

  1. Launch terminal.
  2. Open SSH client configuration file for your user using your preferred text editor. 

    $ vi ~/.ssh/config

  3. Select the host(s) that you want to implement multiplexing. 

    host *

    * applies configuration for all hosts. Other possible host options: 

    example.com *.example.com 192.168.100.10 192.168.100.*

  4. Enable multiplexing for the selected host(s). 

    host *     controlmaster auto

  5. Set how long do you want the multiplexing session to persist. 

    host *     controlmaster auto     controlpersist 10m

  6. Set path and filename for controlmaster file. 

    host *     controlmaster auto     controlpersist 10m     controlpath ~/.ssh/muxmasters/%C

    Create folder if doesn't exist. 

    $ mkdir -p ~/.ssh/muxmasters

  7. Check for existing control file on local host. 

    $ ls ~/.ssh/muxmasters

  8. Log in to a remote host. 

    $ ssh 192.168.111.159 -- hostname [email protected]'s password:  remotehost

  9. Check for created control file to confirm. 

    $ ls ~/.ssh/muxmasters 598a7155ff90f076057fb265730c6ffe5997d4bb

  10. Log in again to the same host to test. 

    $ ssh 192.168.111.159 -- hostname host

    Should be without password and very fast as long as you log in again within the controlpersist time value.