Port 3389 — RDP
Quick reference for TCP/UDP port 3389, used by RDP. Includes what the service does, security guidance and related ports.
What is port 3389?
Remote Desktop Protocol. High-value attacker target — restrict access.
What port does RDP use?
RDP listens on port 3389 by default.
Is port 3389 open? How to check
Run one of these from your computer, replacing HOST with the IP address or domain you want to test.
nc -zv HOST 3389
Test-NetConnection HOST -Port 3389
nmap -p 3389 HOST
A refused or timed-out connection means the port is closed or filtered by a firewall.
Security guidance
High risk — do not expose to the internet
Port 3389 (RDP) is high-risk because the service it carries is a frequent target for credential attacks, brute force or unpatched-vulnerability scanning. Keep it bound to localhost or your VPN, never forward it directly on a router, and require strong authentication.
Related ports
Frequently asked
What is port 3389 used for?+
Port 3389 is the standard TCP/UDP port for RDP. Remote Desktop Protocol. High-value attacker target — restrict access.
What port does RDP use?+
RDP listens on port 3389 by default.
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