TCP 3390
Synopsis
- TCP port 3390 is commonly used for Microsoft Remote Desktop Protocol (RDP) when administrators change the default port 3389 to an alternate value.
- Real-world examples include Windows Server Remote Desktop Services and Windows 10/11 Pro/Enterprise hosts configured to listen on 3390, as well as Linux RDP servers using xrdp that are set to 3390 in some deployments (e.g., containerized setups or custom images).
- Microsoft Remote Desktop clients on Windows, macOS, iOS, and Android can connect to RDP endpoints on 3390 by specifying the port (for example, host:3390), which is a routine operational practice.
- Security note: because 3390 is frequently used as a non‑standard RDP port, attackers scan it for exposed RDP services and attempt brute-force or exploit-based intrusions; RDP vulnerabilities (such as BlueKeep on unpatched systems) apply regardless of the port.
Observed activity
Last 30 days
Detailed chart