vnc (Virtual Network Computing) is an application that is used to access and manage a computer remotely, a program similar to remote desktop used in Windows.
It is based on an application server to be installed on the computer where you want to access and to install a client application vnc on the PC from which you want to manage the computer remotely, you will be able to ‘be in LAN or the Internet: in both cases should be checked and make sure they are open the ports used for communication between 2 PC, in this case the port 5900/tcp, or the link can not ‘happen.
To handle, open and close the doors of communication with the outside of the PC you use the firewall.

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