Should not be public
Port 3000 — Node.js / dev server
The conventional port for a Node, React or Rails development server.
Port
3000
Service
Node.js / dev server
Protocol
TCP
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.
Is port 3000 open on your server?
Test it from outside your network — the only view that matters.
Other common ports
20 · FTP data
21 · FTP control
22 · SSH / SFTP
23 · Telnet
25 · SMTP
53 · DNS
80 · HTTP
110 · POP3
123 · NTP
143 · IMAP
161 · SNMP
389 · LDAP
443 · HTTPS
445 · SMB
465 · SMTPS
587 · SMTP submission
993 · IMAPS
995 · POP3S
1433 · Microsoft SQL Server
1521 · Oracle Database
2082 · cPanel
2083 · cPanel (TLS)
3306 · MySQL / MariaDB
3389 · RDP
5432 · PostgreSQL
5900 · VNC
6379 · Redis
8080 · HTTP alternate
8443 · HTTPS alternate
9200 · Elasticsearch
27017 · MongoDB