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VNC desktop

by Alejandro Liu
in 2017

tagged authentication, desktop, login, security

Updated: 2021-12-25

IDEA:

Client connects >
        < server sends version string (Use 3.3 only)
Client replies with actual verison string >
        < server sends security type; NONE
Client send ClientInit (shared flag) > 
        < sever sens ServerInit (server details) WxHxD Name
=== standard stuff ===

2 VERSIONS

  • kiosk
    • unmodified vncviewer connects to a multiplexer screen
    • server (in inetd mode) first spawns a Xvnc (in inetd mode) which does a login authentication and finds an existing desktop or spawns a new one saves the port and exists
    • server then connects to the new desktop port and does the VNC handshake. Sends client Desktop change and name change messages
    • Forwards everything...
  • command
    • User points command to a server.
    • Script selects a new port.
    • Ssh to server, look for vnc session, or spawn new one.
    • netcat to vnc session.
    • Listen to to new port, and netcat to ssh.
    • vncviewer to netcat port.

We use only v3.3 because we don't want to mess with security types. Security should be handled by SSH tunnel.

Check if user can login