Remote Desktop Assistance

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Nowadays, computer system have tied to our daily life. In the world of multimedia, Personal Computers become essential for almost everybody to carry out daily tasks. More and more people self-learn the basic operation of a PC without spending much effort of learning from educational institution. Microsoft’s Operating System Windows XP, for example, is designed for a wide range of users, no matter if you are a completely new user to computer experts. Many users, however, occasionally hit to a dead lock where they experience problems with the working environment. It can be as little as graphic user interfaces setting, or as big as I/O conflict. Very often, they cannot solve the problem themselves and helps from more experience users will be needed. Nevertheless, without actually sitting in front of the computer, one often experiences difficulties to do the problem solving. One often find themselves having a hard to accurately communicate detailed configuration and information over the phone or text messages Error messages, system behaviors, and other important information are usually hard to be described in verbal reformat. In such situation, Remote Desktop Assistance provides tremendous helps to the user in both sides. Both the normal user and the computer expert can now view and operate in the same desktop, finding hidden setting and tuning windows environment now easier then ever. With the Remote Desktop Assistance technology, one can control the cursor, keyboard and modify files (read or write) of the computer in the other side as needed.

The Remote Desktop technology that integrated in the windows XP is actually built on the Remote Desktop Protocol (RDP). Basically, RDP is an extension of T-120 family of protocol standards. So let’s get into detail on the T.120 standard. The T.120 standard is made up by stack of communication and application protocols, which are originally designed for real time resource sharing across the Internet. Software like NetMeeting from Microsoft, a video conferencing software, also adopted such protocol as the barebones of its technology. T.120 standard enable enhance multimedia, MCU and code control capabilities. And on top of it, there are three important functionalities that T.120 offer: the ability of establishing and maintaining conferences, managing multiple participants and programs multitask, and exchanging data in an error-free and secure manager over different type of networking connections.

The T.120 protocol consists various sub-protocols, including the T.121, T.122, T.123, T.124, T.125, T.126, and T.127. Each and everyone of these contributes important functionality to the protocol. For T.121, it acts as a template or guide for T.120 protocols application, making standardized and non standardized applications consistence. The benefit for this is that unforeseen problems between protocol implementations can be minimized. The T.122, on the other hand, delivers multi-point services to the T.120 protocol. When T.122 pairs with the MCS engine, it serves as an important element for multi-point application design. The T.123 is implemented to specifies different transport profiles, including the Public Switched telephone Networks, Circuit Switched Digital Networks, Integrated Switched Digital Networks, Packet Switched Digital Network, Novell Netware IPX, and TCP/IP. For T.124, it provides facilities for establishing and managing a multipoint conference, namely the Generic Conference Control (GCC). The T.125, multipoint communication Service Protocol, has two major functions: “…defines procedures for a single protocol for the transfer of data and control information from one MCS provider to peer MCS provider (, and the)… structure and encoding of the MCS protocol data units used for the transfer of data and control information…”. T.126 is responsible for transmitting still images across applications, and it is often referred to as document conferencing or whiteboard display. Lastly, the T.127 is responsible for transmitting files between various endpoints in a conference. It supports multiple file to be transfer simultaneously, to the selected participants or all participants. In addition, T.127 allows developers specify priority level of file delivery, and file compressing option is also supported.

The T.120 architecture is based on the multi-layering approach similar to the ISO model in the networking field. Each of those layer relies on the layer below. Protocol T.122,T.123,T.124, and T.125 constructs the lower level layers that allows application independent mechanism, and multipoint data communications services. Protocol T.126 and T.127, on the other hand, belong to upper level layers and they are designed to support specific conferencing application, e.g. binary file transfer and whiteboarding.

On top of the T.120 protocol, the Remote Desktop Assistance is a win32 ActiveX control (COM object), and it runs in the Microsoft Internet Explorer 5 series. The RDA is preinstalled in the Microsoft’s windows XP and computer in other platform it can download the downloadable ActiveX control package for free. The Remote desktop web connection run on any 32-bit windows operating system.

Now, let’s talk about some of the benefits of The RDA technology. As mentioned above, RDA is based on win32 active X control, which enables users to access to computers running windows XP Pro with the RDA feature enabled. It is essentially useful for fast, on-demand access to terminal server for both system administrators and normal users. Another useful feature is by using the functionality of IE, RDA sessions can be embedded in web pages, or a new separate Internet Explorer window. Also, the web site administrator can write simple scripting code to allow users open multiple Remote Desktop session from the same web page. In term of programmability, RDA’s Active X control and COM object nature helps many programmer to insert custom functionality by using Visual Basic or Visual C++. Programmers can now write scripts that communicate between an application running on the desktop and a Terminal Services, hosting applications using Remote Desktop Web Connection and RDP’s virtual channel architecture.

In term of security, the Remote Desktop web connection between computers is highly encrypted. In particular, RDP 5.0 client adopts RSA Security’s RD4 cipher with the selection of 40, 56, or 128bit key strength, perhaps determined by the server to which it is connecting. The TCP port-3389 is reserve for the communication with the server. RDP is designed in a way that the encryption makes it safe to use over the network, since the protocol cannot be easily sniffed to reveal the passwords, credit card numbers, an other sensitive personal data.

Now, we will see how it actually works. In a Remote Assistance session, we usually call the actors novice and expert. In order to use Remote Assistance, both parties must be using Windows XP Pro or Windows Server 2003; and both sides must be have active Internet connections or being connected on the same LAN. Computer in neither can be blocked by firewalls. Now, one can create a new Remote Assistance session by the following three-step process:

Step1, the novice sends a request (a RDA invitation), using windows messenger (MSN messenger) or email.

Step2, the expert accepts the request, and a new terminal window will be opened. The Windows should display the desktop of the novice’s machine.

Step3, the expert can now view the same desktop in the novice’s point of view, although it’s a read-only window. Users in both sides can exchange messages with text or voice chat. Before the expert start working with objects on the remote PC, the novice side must enable the “Allow Expert Interaction” option to gain access to operate the computer. For each Remote Assistance connection, there is a small text file called an RA ticket with an extension .msrcincident This file make use of the XML fields to determine the parameters of a new Remote Assistance connection. If one use Windows Messenger to manage the connection, the RA ticket will not be visible. Only when a novice sends a Remote Assistance request through e-mail, the RA ticket send along as an attachment to the message. When this file get opened by expert, the Remote Assistance session will be launched.

After the expert initials a connection request, and permission is granted by the novice , a two-pane Remote Assistance window will show up on the expert’s machine. The left side of the pane is used for text chat; and the right side of the pane displays the novice’s desktop. As the expert side, he/she may use the toolbar at the top of the Remote Assistance window. The novice will get similar user interface, except the format of the toolbar is slightly different. For security-related issues, only by clicking the “Take Control” button can result a complete control for the system, and permission has to be granted before he/she can actually begin working with the remote desktop. At all time, the novice can observer what the expert doing, and the novice had the right to cut off the expert’s ability to control the session by tapping the Esc key, or by simply clicking the “Release Control” button on the toolbar.

Actions in a Remote Assistance session are governed by the privileges level, which assigned to the novice user’s account. When connecting to a machine that the current user’s account is limited, the expert may not be able to edit the registry or make configuration changes unless the administrator’s password is entered using the “Run As” dialog box.

Finally, let’s go over some of issue or trouble spots related to routers and firewalls on the RDP.

A Remote Assistance connection is can be established easily when both parties have public IP addresses provided by their Internet service provider. In such case, computers in both side are to connect directly, sending and receiving data using TCP port-3389. Routers through the Internet connection between the two computers would be able to recognize the of both sides, forwarding and packets from host to their correct destination. For the software base Internet Connection Firewall in Windows XP, it automatically opens the port-3389 when application requests a new Remote Assistance connection.

Remote Assistance connections are friendly to a private network such as a workgroup setting in home or small office. Different machine can “talk” directly with the others without having to pass through any routers. However, if both of the computer a behind private network, things will get a little more complicated. Since these addresses are reserved for exclusive use on private networks, they can not easily be rerouted over the Internet. In such situation, a software or hardware-based NAT device would be handy to pass data between the single public IP address (valid IP) and the private IP addresses on the local network.

Overall, Remote Desktop Assistance is a great tool for people who need helps remotely from other location. This software saves both the expert and novice a lot times by eliminating the need of describing the situation in English. Indeed, a picture really worth a thousand words, not to mention this is real time interaction!