Remote Desktop Protocol

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Remote Desktop Protocol ( RDP ) is a proprietary protocol developed by Microsoft, which provides users with a graphical interface to connect to other computers via a network connection. Users use the RDP client software for this purpose, while other computers must run the RDP server software.

Clients exist for most versions of Microsoft Windows (including Windows Mobile), Linux, Unix, macOS, iOS, Android, and other operating systems. The RDP server is built into the Windows operating system; RDP servers for Unix and OS X also exist. By default, the server listens on TCP port 3389 and UDP port 3389.

Microsoft currently refers to their official RDP client software as Remote Desktop Connection, formerly "Terminal Services Client".

This protocol is an extension of the ITU-T T.128 application sharing protocol.

Video Remote Desktop Protocol

Histori

Each version of Microsoft Windows from Windows XP and beyond includes the installed Remote Desktop Connection (RDC) ("Terminal Services") client ( mstsc.exe ) whose version is determined by the operating system or by the latest Windows Service Pack. Server Terminal Services is supported as an official feature on Windows NT 4.0 Terminal Server Edition, Windows 2000 Server, all editions of Windows XP except Windows XP Home Edition, Windows Server 2003, Windows Home Server, on Windows Fundamentals for Legacy PCs, in Windows Vista Ultimate, Enterprise and Business, Windows Server 2008 and Windows Server 2008 R2 and Windows 7 Professional and later.

Microsoft provides the clients necessary to connect to newer RDP versions for lower level operating systems. Because server upgrades are not available downlevel, the features introduced with each newer RDP version only work on lower level operating systems when connecting to higher version RDP servers from these older operating systems, and not when using RDP server in old operating system.

Version 4.0

Based on the ITU-T T.128 application sharing protocol (during the draft also known as "T.share") from the T.120 recommendation series, the first version of RDP (named version 4.0) was introduced by Microsoft with "Terminal Services", as part of the product their Windows NT 4.0 Server, Terminal Server Edition. Terminal Services Edition NT 4.0 relies on MultiWin Citrix technology, previously provided as part of Citrix WinFrame over Windows NT 3.51, to support multiple users and login sessions simultaneously. Microsoft requires Citrix to license their MultiWin technology to Microsoft in order to be allowed to continue offering their own terminal-service products, then name Citrix MetaFrame, on top of Windows NT 4.0. The Citrix-supplied DLL included in Windows NT 4.0 Terminal Services Edition still carries Citrix copyright instead of Microsoft copyright. Newer versions of Windows integrate needed support directly. The T.128 application sharing technology was acquired by Microsoft from the UK software developer, Data Connection Limited.

Version 5.0

This version was introduced with Windows 2000 Server, adding support for a number of features, including printing to local printers, and aiming to increase network bandwidth usage.

Version 5.1

This version was introduced with Windows XP Professional, including support for color and 24-bit sound. Client is available for Windows 2000, Windows 9x, Windows NT 4.0. With this version, the client name is changed from Terminal Services Client to Remote Desktop Connection ; The remains remain to this day, however, as the underlying executable is still named mstsc.exe .

Version 5.2

This version was introduced with Windows Server 2003, including support for console mode connections, session directories, and local resource mapping. It also introduces Transport Layer Security (TLS) 1.0 for server authentication, and for encrypting terminal server communications. This version is built into Windows XP Professional x64 Edition and Windows Server 2003 x64 & amp; X86 Edition.

Version 6.0

This version was introduced with Windows Vista and brings together support for Windows Presentation Foundation applications, Network Level Authentication, multi-monitor covers and large desktop support, and TLS 1.0 connections. Version 6.0 client is available for Windows XP SP2, Windows Server 2003 SP1/SP2 (x86 and x64 editions) and Windows XP Professional x64 Edition. Microsoft's Remote Desktop Connection Client for Macintosh OS X is also available with support for Intel and PowerPC Mac OS version 10.4.9 and higher.

Server 2012 can support RDC 6.0 or later.

Version 6.1

This version was released in February 2008 and is included with Windows Server 2008, as well as with Windows Vista Service Pack 1. Client is included with Windows XP SP3. In addition to changes related to the way remote administrators connect to "console", this version has new functions introduced in Windows Server 2008, such as remote-linking to individual programs and new client-side printer redirection systems that make client print capabilities available to apps that runs on the server, without having to install the print driver on the server.

Version 7.0

This version was released for manufacturing in July 2009 and included with Windows Server 2008 R2, as well as with Windows 7. With this release, also changed from Terminal Services to Remote Desktop Services

Most of the RDP 7.0 features such as the use of Aero glass remote, two-way audio, Windows Media Player redirection, dual monitor support and Remote Desktop Easy Print are only available in Windows 7 Enterprise or Ultimate editions.

SP1 and Server 2008 R2 SP1. This adds RemoteFX functionality.

Version 8.0

This version is released on Windows 8 and Windows Server 2012. This version has new functions like Adaptive Graphics (progressive rendering and related techniques), TCP or UDP automatic selection as transport protocol, multi touch support, DirectX 11 support for vGPU, USB redirection supported independently of vGPU support, etc. The "connection quality" button is displayed in the RDP client connection bar for RDP 8.0 connections; clicking it provides more information about the connection, including whether UDP is being used or not.

The client and server components of RDP 8.0 are also available as add-ons for Windows 7 SP1. The RDP 8.0 client is also available for Windows Server 2008 R2 SP1, but the server component is not. This plugin requires the DTLS protocol to be installed as a prerequisite. After installing the update, for the RDP 8.0 protocol to be enabled between Windows 7 machines, additional configuration steps are required using the Group Policy editor.

New features in RDP 8.0 are limited support for nested RDP sessions; only works for Windows 8 and Server 2012, Windows 7 and Server 2008 R2 (even with RDP 8.0 update) does not support this feature.

The "shadow" feature of RDP 7, which allows administrators to monitor (latch) on RDP connections has been removed in RDP 8. Aero Glass remoting feature (applicable to Windows 7 machines connected to each other) has also been removed in RDP 8.

Version 8.1

This version was released with Windows 8.1 and Windows Server 2012 R2. The RDP 8.1 client update exists for Windows 7 SP1 as well, but unlike RDP 8.0 update for Windows 7, it does not add RDP 8.1 server components to Windows 7. In addition, if the RDP 8.0 server function is desired in Windows 7, KB 2592687 (RDP update 8.0 client and server) must be installed before installing RDP 8.1 update.

Support for shadow sessions added back in RDP version 8.1. This version also fixes some visual disturbances with Microsoft Office 2013 when running as RemoteApp.

Version 8.1 of RDP also allows "unlimited admin" mode. Entering this mode requires only knowledge of a hashed password, and not from its plaintext, therefore making a hash attack possible. Microsoft has released an 82-page document explaining how to mitigate this type of attack.

Version 10.0

Version 10.0 of RDP includes the following new features: AutoSize Zoom (useful for HiDPI clients). Additionally improved graphics compression includes using H.264/AVC.

Maps Remote Desktop Protocol

Features

• 32-bit color support. Colors of 8-, 15-, 16-, and 24-bit are also supported.
• 128-bit encryption, using RC4 encryption algorithm, starting Version 6.
• Audio Redirection allows users to process audio on the desktop remotely and switch the sound to their local computer.
• File System Redirection allows users to use their local files on the desktop remotely in a terminal session.
• The Redirection Printer allows users to use their local printers in terminal sessions as well as with local printers or shared networks.
• Port Redirection allows applications running in terminal sessions to access local serial and parallel ports directly.
• The remote computer and the local computer can share clipboards.

Microsoft introduced the following features with the release of RDP 6.0 in 2006:

• Seamless Windows: remote applications can run on client machines served by Remote Desktop connections. It's available since RDP 6.
• Remote Program: app issuance with client-side file type associations.
• Terminal Services Gateway: allows the ability to use an IIS front-end server to accept connections (via port 443) for a back-end Terminal Services server via https connection, similar to how RPC over https allows Outlook clients to connect to an Exchange 2003 server back-end. Requires Windows Server 2008.
• Network Level Authentication
• Support for remoting the Aero Glass Theme (or Desktop Consist), including ClearType font smoothing technology.
• Support for Windows Presentation Foundation application remotations: compatible clients that have.NET Framework 3.0 support can display various effects of Windows Presentation Foundation on local machines.
• Rewrite device redirects is becoming more common, allowing more types of devices to access.
• Can be fully configured and can be scripted via Windows Management Instrumentation.
• Increased bandwidth alignment for RDP clients.
• Support for Transport Layer Security (TLS) 1.0 on server and client expires (negotiable if both parties agree, but not required in default configuration of any version of Windows).
• Multiple monitor support to allow one session to use multiple monitors on the client (disable desktop composition)

The 7.1 release of RDP in 2010 introduced the following features:

• RemoteFX: RemoteFX provides virtual GPU support and host-side encoding; it is shipped as part of Windows Server 2008 R2 SP1.

src: securingtomorrow.mcafee.com

Security issues

Version 5.2 of RDP in its default configuration is vulnerable to man-in-the-middle attacks. Administrators can enable transport layer encryption to reduce this risk.

RDP sessions are also vulnerable to credentials in memory harvest, which can be used to initiate a hash attack.

In March 2012, Microsoft released an update for critical security vulnerabilities in the RDP. The vulnerability allows Windows computers to be compromised by unauthorized clients and computer worms.

The RDP 6.1 client version can be used to reveal the names and images of all users in the RDP Server (regardless of which version of Windows) to select one, if no user name is specified for RDP connections.

In March 2018 Microsoft released a patch for CVE-2018-0886, a remote code execution vulnerability in CredSSP, which is a Security Support Provider involved in Microsoft Remote Desktop and Windows Remote Management, found by Preempt.

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Non-Microsoft Implementation

There are many non-Microsoft implementations of clients and RDP servers that implements a subset of Microsoft functions. For example, the rdesktop open-source command line client is available for Linux/Unix and Microsoft Windows operating systems. There are many GUI clients, such as tsclient and KRDC, built on rdesktop; CoRD is a client for Macintosh.

In 2009, rdesktop was forked as FreeRDP, a new project aimed at modulating code, handling problems, and implementing new features. FreeRDP comes with its own xfreerdp command-line-client, which supports Windows Seamless in RDP6. There is also a GTK Application called Remmina.

The open-source implementation of the Remote Desktop Protocol server on Unix is ​​FreeRDP and xrdp. Remote Desktop Connection Client Windows can be used to connect to the server. Patented RDP client solutions such as rdpclient are available as stand-alone applications or embedded with client hardware.

The new access paradigm, browser-based access, has enabled users to access Windows desktop and applications on each RDP host, such as Microsoft Remote Desktop (RDS) Session Hosts (Terminal Services) and virtual desktops, as well as remote physical PCs.

There is also a VRDP that is used in VirtualBox virtual machine implementation by Oracle. This protocol is compatible with all RDP clients, such as those provided with Windows but, unlike the original RDP, can be configured to accept unencrypted connections and unprotected passwords, which may be useful in secure and trusted networks, such as home or office LANs. By default, the Microsoft RDP server refuses connection to a user account with a blank password (but this can be changed with Group Policy Editor). The external and guest authorization options are provided by VRDP as well. It does not matter what operating system is installed as a guest because VRDP is implemented on a virtual machine (host), not on the guest system. An exclusive VirtualBox Extension package is required.

src: cdn.instructables.com

Patent

Microsoft requires third party implementation to license the relevant RDP patents from itself. In February 2014, the extent to which open-source clients meet this requirement is still unknown.

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See also

• Comparison of remote desktop software
• Desktop virtualization
• SPICE and the RFB protocol - other desktop remoting protocols
• Virtual private server

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References

src: kemptechnologies.com

External links

• Remote Desktop Protocol - from the Microsoft Developer Network
• Understanding Remote Desktop Protocol - from support.microsoft.com
• How to Connect to RDP? - from Web Pundits
• MS-RDPBCGR: Remote Desktop Protocol: Basic Connectivity and Graphic Remoting Specifications - of the Microsoft Developer Network

Source of the article : Wikipedia