Remote desktop protocol (RDP) is a secure network communications protocol designed for remote management, as well as for remote access to virtual desktops, applications and an RDP terminal server.
RDP allows network administrators to remotely diagnose and resolve problems individual subscribers encounter. RDP is available for most versions of the Windows operating system. RDP for Apple macOS is also an option. An open source version is available, as well.
Features and functions
Noteworthy properties of RDP include encryption, smart card authentication, bandwidth reduction, resource sharing, the ability to use multiple displays and the ability to disconnect temporarily without logging off. RDP also allows for the redirection of functions such as audio and printing.
RDP can support up to 64,000 independent channels for data transmission. Data can be encrypted using 128-bit keys, and the bandwidth reduction feature optimizes the data transfer rate in low-speed connections.
How the remote desktop protocol works
The RDP protocol is designed to provide remote access through port 3389. An RDP-enabled application or service packages the data that is to be transmitted, and the Microsoft Communications Service directs the data to an RDP channel. From there, the operating system encrypts the RDP data and adds it to a frame so that it can be transmitted.
The Terminal Server Device Redirector Driver handles all RDP protocol activity. This driver is made up of subcomponents such as the RDP driver (Wdtshare.sys), which handles user interfaces, transfers, encryption, compression and framing. The transport driver (Tdtcp.sys) is responsible for packaging the protocol in such a way that allows it to be sent across a TCP/IP network.
The protocol has presented some security issues in the past, however. Early versions contained a vulnerability that allowed an RDP session to fall victim to a man-in-the-middle attack, through which the attacker could gain unauthorized access.
Newer versions of RDP are far more secure. More recent Windows operating systems contain a mechanism for specifying which users are allowed to access the system through an RDP session. There is also an option to prevent anyone from remotely accessing the system unless they are using network-level authentication.
It is generally recommended that administrators and end users only use RDP when it is absolutely necessary, and that they run it with the lowest level of privilege possible.