See if a port forwarded on your router is reachable from the internet
Checked from our server in India. Only the address you type is sent to us; nothing else leaves your device. Updated on 23 Oct 2026.An open port checker answers one question after you forward a port on your router: can the internet reach it? Type your public IP or host name and a port, or tap one of 20 common ones such as 25565 for Minecraft, and our server tries one connection from outside: open, closed or filtered.
| Port | Usually | Port | Usually |
|---|---|---|---|
| 80 | HTTP | 443 | HTTPS |
| 22 | SSH | 21 | FTP |
| 25 | SMTP | 587 | Mail submission |
| 465 | SMTPS | 993 | IMAPS |
| 995 | POP3S | 143 | IMAP |
| 110 | POP3 | 53 | DNS (TCP) |
| 3389 | Remote Desktop | 3306 | MySQL |
| 5432 | PostgreSQL | 6379 | Redis |
| 27017 | MongoDB | 8080 | HTTP alternate |
| 8443 | HTTPS alternate | 25565 | Minecraft |
Type the host name or public IP address, and the port, or pick a common port.
Press Check port. Our server makes one connection, which takes at most 5 seconds.
Read whether the port is open, closed or filtered, then copy the result.
The Port Checker answers one question: can a service on this port be reached from the internet? Our server opens a single TCP connection to the host and port you give it and closes it the moment it opens, without sending anything. Because the attempt comes from outside your own network, it tests exactly what a visitor, a customer or a game client would hit.
There are four possible answers. Open means the handshake completed: something is listening and accepted the connection. Closed means the host answered with a refusal: it is up, but nothing is listening on that port. Filtered means no answer arrived within 5 seconds: a firewall is dropping the attempt, the router has no forwarding rule, or the host is offline. Unreachable means a router on the way reported there is no route.
The usual reason for a forwarded port showing filtered is the forwarding rule itself: the wrong inside address, the wrong protocol, or a second router in front of the first. Some providers block common ports for home connections, and mobile networks behind carrier-grade NAT cannot accept incoming connections at all.
The rest of the article, and all 6 questions about Port Checker, are on the Port Checker page.
A closed port means the host answered and refused the connection, so the machine is up but nothing listens there. A filtered port means no answer arrived at all within 5 seconds, which usually points to a firewall silently dropping the attempt, a missing router forwarding rule, or a host that is offline.
The most common causes are a forwarding rule pointing at the wrong inside IP address, a firewall on the computer itself, the service not running, or a second router in front of yours. Mobile and some broadband connections use carrier-grade NAT, which cannot accept incoming connections at all.
No. Our server completes the TCP handshake and closes the connection immediately, without sending a single byte of data. The service on the port sees a connection that opened and closed, which some servers note in their logs.
No, only TCP. A UDP service gives no reply unless it receives a request it understands, so an open UDP port looks the same as a filtered one from outside. Test UDP services, such as voice chat or DNS, with the client software that uses them.
Still stuck? Ask about Port Checker and anybody who knows can answer. No account needed.
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