Description
3389 port used for Remote Desktop requires TCP port 3389 to be open. Also, opening UDP port 3389 enables acceleration since RDP 8.0. It is possible to change the port used by the terminal server (or PC which is accessed), see this Microsoft support article: How to change the listening port for Remote Desktop..
3389 port is used for Remote Desktop Protocol (RDP) is a proprietary protocol developed by Microsoft to remotely connect to a Windows system using a graphical user interface. RDP is built into Windows by default. RDP listens on TCP port 3389 and udp port 3389. Previously, the RDP software was called Terminal Services client but now it’s called Remote Desktop Connection.
3389 com RDP’s default port 3389 can be used to launch on-path attacks. BlueKeep was one of the most serious RDP vulnerabilities and it was officially labeled as CVE-2019-0708. It was a remote-code execution (RCE) with no authentication and adhered to a specific format. It was workable and ended up spreading to other machines within the network.