Port 3000 — Node.js / dev server

Security guidance

Development servers are not hardened for the internet. Put a real web server in front and bind the app to 127.0.0.1.

Test port 3000 yourself

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

macOS / Linux — netcat

nc -vz example.com 3000

Any OS — nmap

nmap -p 3000 example.com

Windows — PowerShell

Test-NetConnection example.com -Port 3000

open = a service answered on port 3000; 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