Open port testing guide
Check if a TCP port is open, closed, or blocked from the public internet
DevBoxy Port Checker helps you test whether a server, website, router, VPS, firewall, or cloud instance is accepting public TCP connections. Enter a hostname or IP address with a port number to see if that port can be reached from outside your local network.
Use this tool when you are setting up web hosting, SMTP, SSH, FTP, database access, game servers, VPN services, remote desktop, or custom application ports. It is useful for developers, system administrators, DevOps teams, and anyone troubleshooting network connectivity.
If a port shows as closed, the issue may be a local firewall, cloud security group, router NAT rule, wrong service binding, DNS pointing to the wrong host, or the application not listening on that port.
When to use it
- Verify website ports like 80 and 443
- Check SMTP ports for email delivery
- Confirm SSH, FTP, VPN, or RDP access
- Test firewall and router forwarding rules
Common ports
- 80 HTTP, 443 HTTPS
- 22 SSH, 21 FTP
- 25 SMTP, 587 Submission, 993 IMAP SSL
- 3306 MySQL, 5432 PostgreSQL
If a port is closed
- Confirm the app is running on the server
- Allow the port in your server firewall
- Check cloud security group inbound rules
- Verify DNS points to the correct public IP