Backlink: reference-notes-readme
VNC was created as a vendor agnostic graphical desktop solution and is widely deployed in *nix environments. Historically it was commonly deployed without authentication. Modern servers strongly urge administrators to configure a password.
Port: 5900/TCP
Tools: The plethora of open-source VNC applications, RealVNC, TightVNC, Screen Sharing (Mac)
Examples
vncviewer