Remote desktop applications

Long-Distance Relationship

© Lead Image © alphaspirit, 123RF.com

© Lead Image © alphaspirit, 123RF.com

Article from Issue 189/2016
Author(s):

Remote desktop applications allow remote access to machines, including desktop sharing, which makes them useful assistants in both the personal and professional spheres. We look at a few candidates.

If you need to administer computers over a long distance – whether for work or to help out friends or relations – the time for remote desktop software has arrived. It allows admins to repair the desktops of far-flung relatives in their free time. The software also comes in useful for businesses looking to provide support for their customers from afar. Desktop sharing is a core function, which means if a developer wants to present a new website to their colleagues, they can do so with ease.

In the end, roughly two types of remote desktop applications can be distinguished, with fairly fluid definitions. On remote desktop applications using virtual network computing (VNC), one machine operates as the server. It sends the image of its desktop as a compressed bitmap to the client. The programs run on the server; the user manages them on the client by sending mouse movements and keystrokes to the server.

During desktop sharing, applications that use remote desktop protocol (RDP) or proprietary protocols send screen content as terminal servers. This is sent over the network to one or more clients (multichannel) in the form of primitives, a mixture of images and information. They can even transmit the desktop sound if needed. The users then work on the server's desktop, alone or in parallel with other users, as if sitting directly in front of it.

Both software categories overlap when it comes to their functionality. Newer software, for example, makes it possible to simultaneously chat, send files, make calls over the Internet, and transfer videos. This article looks at the way long-distance relationships work with RealVNC [1], TightVNC [2], TeamViewer [3], AnyDesk [4], NX [5], and its free offshoot X2Go [6]. We will be comparing functions and performance and considering the technology behind them.

VNC: Framebuffer Ahead

RealVNC and TightVNC are part of a group of remote desktop applications that rely on VNC [7]. The basic technology behind VNC is the platform-independent remote framebuffer protocol (RFB) [8]. It works at framebuffer level, so it functions for window-based systems like Windows, OS X, or X11, but also makes cross-platform connections possible. RFB transfers the screen content as bitmaps, where the server only responds to a client-side FramebufferUpdateRequest with the changes since the last request (FrameBufferUpdate).

In contrast with the members of the VNC camp, the remote support tools TeamViewer and AnyDesk use proprietary protocols. NoMachine's NX and the free implementation X2Go fall under the category of terminal servers, though they fulfill the purpose of a remote desktop program. Their advantage over VNC lies in their complete encryption of data traffic. In contrast with some VNC applications, their users do not have to manually set up port forwarding if the remote machine is not part of the local network.

Versatile Use

Use of VNC is versatile. Sales reps can connect with company branches over the protocol. Because not all VNC variants encrypt, the admins often secure these sessions with the help of secure shell (SSH) tunnels. Together, they beat the problem of port forwarding at the same time. Companies with a number of field staff can save money thanks to free VNC clients, because tools like TeamViewer or AnyDesk charge fees for commercial use. At the same time, the data exchange remains under their own control.

The admin also controls servers that require a graphical interface via VNC. The hypervisor VirtualBox offers VNC to operate a virtual machine without display (headless) [9].

RealVNC

The remote desktop application RealVNC (Figure 1) uses the RFB protocol. It operates across platforms and can be set up on Unix-flavored systems like Linux, OS X, Solaris, HP-UX, and AIX, and also on Windows and the Raspberry Pi. The current Linux distributions offer their own packages for RealVNC. In Debian, these are vnc4server and xvnc4viewer; for RPM-based distributions, they are realvnc-vnc-server and realvnc-vnc-viewer. Meanwhile, apps are also available for the viewer for Android and iOS.

Figure 1: The admin establishes the connection with RealVNC via the command line.

The software is written in Java and licensed under the GPL along with proprietary licenses. The developers offer four editions of RealVNC. The Open Edition costs nothing, although you do have to register and activate the software. Since version 5, there has also been a Free Edition as well as the Open Edition; this demands a free license key.

The Personal Edition and Enterprise Edition are both commercial releases, and they essentially differ in their target group. The Personal Edition is aimed at home users and small businesses (as well as Windows users with Vista or later installed), whereas the Enterprise Edition is for larger firms. Unlike the free Open Edition, both of these encrypt and allow users to exchange files, chat, and print on remote devices.

As the admin, you install VNC (in one of its variants) on the machine you want to control. You then run a VNC viewer on the client, which attempts to access the remote device. Viewer and server then establish a point-to-point connection, which allows secure communication when encrypted.

RealVNC is mainly suited to remotely accessing your own machine, but it is also a remote helpdesk application. The pricing model for the commercial variants depends on the number of desktops you want to monitor, as well as virtual ones. The vendor charges $30 per desktop for the Personal Edition, while the Enterprise Edition comes in at $44.

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