Port 3389 — RDP

Security guidance

One of the most attacked ports on the internet and a primary ransomware entry point. Put it behind a VPN, always.

Test port 3389 yourself

From your own machine, against any host (swap in your domain):

macOS / Linux — netcat

nc -vz example.com 3389

Any OS — nmap

nmap -p 3389 example.com

Windows — PowerShell

Test-NetConnection example.com -Port 3389

open = a service answered on port 3389; closed = the host replied but nothing is listening; filtered = a firewall silently dropped the probe. These test from your network — our port checker tests from the outside, the view that matters for security.

Other common ports