VNC (Virtual Network Computing) is a protocol that allows a technician to simultaneously view and control a user's screen remotely. VNC uses a server-client model, where the user's computer runs a VNC server and the technician's computer runs a VNC client. VNC can work across different platforms and operating systems3.
SSH (Secure Shell) is a protocol that allows a technician to access a user's command-line interface remotely, but not their graphical user interface. VPN (Virtual Private Network) is a technology that creates a secure and encrypted connection over a public network, but does not allow screen sharing. RDP (Remote Desktop Protocol) is a protocol that allows a technician to access a user's desktop remotely, but not simultaneously with the user.