How do I check if port 3389 is open?

Enter your public IP or hostname into the scanner tool and click Check. A sub-second raw TCP socket handshake will be initiated from our edge server to port 3389 on your target. If the 3-way handshake finishes with SYN-ACK, the port is OPEN. If an RST packet is returned, the host is reachable but the port is CLOSED. If packets time out without response, the port is FILTERED by an ISP or firewall.

Why does port 3389 show as closed or filtered?

If port 3389 reports CLOSED or FILTERED, confirm that: 1) Your service is actively running and bound to 0.0.0.0 (not just localhost/127.0.0.1); 2) Your router has a port forwarding rule directing external port 3389 to your machine's local IP; 3) Your operating system firewall (Windows Defender Firewall, ufw, or iptables) allows incoming connections on port 3389.

PORT 3389 TCP Remote Access Critical Risk

Port 3389 (Remote Desktop Protocol (RDP)) Open Check

Q: What is port 3389 used for?

Port 3389 is the standard TCP port used for Remote Desktop Protocol (RDP). It is commonly used by Windows Remote Desktop, xrdp (Linux), Apache Guacamole. Microsoft proprietary protocol providing graphic remote desktop management for Windows hosts.

Q: Is port 3389 safe to expose to the public internet?

Exposing port 3389 carries elevated security risks (Critical risk). Severe security risk. Direct RDP exposure to WAN is the #1 vector for ransomware deployment. Always access RDP through a VPN or RDP Gateway with MFA. For remote services, consider placing them behind a secure VPN (such as WireGuard or Tailscale) or restricting inbound access with strict IP firewall rules.

Microsoft proprietary protocol providing graphic remote desktop management for Windows hosts.

Live Socket Reachability Probe

Pre-configured for Port 3389

Port Scanner

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Recent Probes 0

Stored locally in browser • 0 logs on server

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Target hosts and tested ports will appear here automatically for fast 1-click re-testing.

Auto-prunes oldest probes beyond 10 entries (FIFO)

Port Specifications & Network Behavior

Standard Port Number 3389

Primary Service Remote Desktop Protocol (RDP)

Transport Protocol TCP

Traffic Classification Remote Access

Residential ISP Status Typically unrestricted by consumer ISPs

Security Exposure Critical Exposure discouraged without VPN or firewall protection

Security Advisory: Remote Desktop Protocol (RDP) (Port 3389)

Severe security risk. Direct RDP exposure to WAN is the #1 vector for ransomware deployment. Always access RDP through a VPN or RDP Gateway with MFA.

Recommendation: Keep port 3389 closed to WAN traffic. Connect remotely using WireGuard, Tailscale, or an SSH tunnel.

Port Forwarding & Troubleshooting Checklist

If port 3389 returns CLOSED or FILTERED, work through this verified diagnostic checklist:

1 Ensure 'Allow remote connections to this computer' is enabled in Windows System Properties.
2 Verify Windows Defender Firewall allows 'Remote Desktop (TCP-In)'.
3 Check that user accounts have strong complex passwords and Network Level Authentication (NLA) is active.

Verify Host Is Listening Locally

Windows (PowerShell) netstat -ano | findstr :3389

Linux / macOS (Bash) ss -tulpn | grep :3389