Why use VNC? Comparison of RDP and VNC protocols.

Every day lots of people use all the benefits of remote access as this is the best way to control distant computer. There are 2 well-known and most common protocols – VNC and RDP that allow accessing to the remote screen easily and securely.

VNC vs. RDP. What's the difference between RDP vs VNC

Let’s understand what RDP and VNC protocols are and how they work.

Remote Desktop Protocol (RDP) is a secure network communications protocol for Windows-based applications running on a server. It is made for support various types of network topologies and multiple LAN protocols.

RDP supports separate virtual channels for the data transmission between devices and allows presenting data from the server. RDP also provides an extensible base and supports up to 64,000 separate channels for data transmission and provisions for multipoint transmission.

There are some key features of RDP:

  • Support for 32-bit color;
  • 128-bit encryption using the encryption algorithm RC4;
  • Sound from a remote computer or server is forwarded and reproduced on the local computer;
  • Allows connecting local resources to the remote machine (mapping);
  • Allows you to use a local or network printers on a remote computer (server);
  • Allows applications running within the current session to access local serial and parallel ports;
  • You can exchange information via the clipboard.

Virtual Network Computing (VNC) is graphical desktop sharing system that uses RFB (Remote Frame Buffer) protocol. It transmits keystrokes and mouse movements from one computer to another relaying the screen updates in the opposite direction on the network.

VNC allows user to access and control your desktop applications wherever you are in the world, whenever you need to. VNC has a widespread user base, from the world’s largest multi-national companies to private users.

Main features of VNC-protocol:

  • VNC sends graphics primitives and event messages from client to server
  • The machine where VNC server is running on does not need to have a physical display. VNC by default uses TCP port 5900+N,[6][7] where N is the display number (usually :0 for a physical display).
  • it may require advanced NAT, firewall and router configuration such as port forwarding in order for the connection to go through
  • VNC is used as a cross-platform remote desktop system
  • VNC may be tunneled over an SSH or VPN connection which would add an extra security layer with stronger encryption
  • VNC integrates seamlessly with other components
  • It is secure; the password is not sent over the Network

The difference between VNC and RDP protocols

When compare VNC and RDP protocols we can notice that VNC uses TCP what means small packet loss. Therefore VNC practically has not “No updated area” effect, in contrast to the RDP that chases its packages by UDP. These two protocols are pretty different in their method of change streaming. The RDP protocol from MS is an extension of ITU standard (T.128). It implements lots of bandwidth-saving techniques that complement each-other and make it very efficient over low bandwidth.

While VNC has very basic compression techniques: it sends blocks of bitmap that have changed and will use basic types of compression, from RLE to jpeg to transmit those blocks efficiently.

RDP appears to transmit blocks of bitmap graphics (say 100x100px) in order to build the full picture (this process can be quite slow) but transfers normal painted shapes/fills, or font drawing to the client extremely quickly. VNC takes giant snapshots of the screen, compare a previous image and stream the changes to the client.

VNC basically has no knowledge of the underlying graphic primitives used to build the screen. That makes it easy to use on any PC because it just monitors changes to the screen bitmap.
RDP on the other hand hooks deeper into the Windows API and can optimize its stream based on the minimum amount of information necessary to generate the same update on the client.

Why VNC could perform with additional benefits?

–          Ability to see connected user actions

You can be anywhere in the world and still be able to quickly and easily connect to your computer remotely. It is very useful for remote PC monitoring and serving a large number of geographically dispersed servers.

–          Ability to share screen to multiple viewers

Several clients are able to connect to a single VNC-Server at once (in contrast to RDP). Remote desktop access can be specifically useful for various specialists enabling in-depth monitoring, including CPU & memory utilization and pull analytics. Screen sharing VNC software can be utilized by a wide range of companies to organize telecommuting.

–          Functional and robust cross-platform solution

VNC is a cross-platform tool that provides remote access to Linux, UNIX, Mac OS X, Windows and other systems of any type of client. In Linux VNC Server either reflects the screen contents of the local X server to a remote computer, or contains its own X- server that can work regardless of what drives local screen. This configuration eliminates the need to reverse the network connection, as well as VNC clients and servers are available for many operating systems, the same client program provides access to any server.

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