Written by In the previous article we saw how to open a shell on the remote computer and (hopefully) do some graphics application. If you want more control over the server that includes the performance of graphics applications and control the desktop, you have to resort to more sophisticated solutions. We are talking about the protocol vnc (Virtual Network Computing), which allows you to remotely control the desktop, receiving input and sending output, so you can access the session currently vnc open.
vnc is a desktop sharing system which uses the RFB protocol to administer your remote computer by installing a vnc server on your machine and setting an appropriate password is vnc allows clients to receive a picture of the screen and to send keyboard and mouse input to the server, in fact, we can manage the server from another location, like your physical computer. The RFB Protocol, used by vnc, is very simple, based on a graphic primitive sent from server to client (“Draw a rectangle of pixel at location X, Y
specified “), taking into account that the image must be gradually updated. However, this means that vnc, in its simplest form, often using a lot of bandwidth, which is why they were put in place several mechanisms to reduce the overhead of communication. For example, you can only send the rectangles that change between one frame and the next, but of course this mechanism only works well if a small portion of the screen is changed (for example, the mouse pointer is moved or a character that was written ), while almost all the advantages we lose if for example we want to see a video or move a window. The obvious consequence is that VNC gives its best when you use a broadband connection (LAN, DSL, etc..).
Regarding the safety aspect, the default vnc is not secure, because the data are transmitted in the clear. However, you can make it safe tunneling over SSH or VPN connection, so that data is sent fully encrypted in a tunnel (we shall see later).
vnc can also be used on Linux to create new sessions to be accessed, but this article we will just access to the current session, ie the so-called “desktop sharing”.
Read related article at Accessing the current graphical session remotely (VNC)
