Port 3389 – RDP (Remote Desktop) Protocol Specification

Technical analysis, security advisories, vulnerability mitigation, and firewall syntax for TCP/UDP port 3389 (RDP (Remote Desktop)).

Port Number 3389

Transport Protocol TCP/UDP

Port Range Type Registered (1024-49151)

Default Status Restricted / LAN

Service Description & Architectural Context

Microsoft Remote Desktop Protocol for Windows server administration.

IANA / RFC Designation:

Port 3389 is assigned to RDP (Remote Desktop) under the Internet Assigned Numbers Authority (IANA) service name registry. In enterprise infrastructure and homelab setups, services listening on this port must follow the principle of least privilege.

Security Analysis & Attack Surface Assessment

High-value ransomware target. Do not expose directly; use RD Gateway or VPN.

Hardening Recommendations:

Do not expose port 3389 to public WAN interfaces unless authenticated TLS or VPN wrapping is strictly enforced.
Enforce rate-limiting using Fail2ban, CrowdSec, or cloud edge DDoS protection.
Audit active listening sockets locally: ss -tulpn | grep :3389 or netstat -ano | findstr :3389.

Firewall Rule Snippets for Port 3389

UFW (Ubuntu / Debian Linux)

sudo ufw allow 3389/tcp

iptables (Standard Linux Kernel)

sudo iptables -A INPUT -p tcp --dport 3389 -j ACCEPT

Windows PowerShell (Defender Advanced Firewall)

New-NetFirewallRule -DisplayName "Allow Port 3389" -Direction Inbound -LocalPort 3389 -Protocol TCP -Action Allow

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