Open Port Checker
Check whether a TCP port on your server or home connection is reachable from the internet — for SSH, web, mail, databases or remote desktop.
How it works
Open, closed and filtered
What the check does
We open one TCP connection from our servers to the address and port you choose and close it again. For SSH, FTP and mail ports we also show the greeting the server sends.
Port forwarding at home
If a port is open on your computer but filtered here, check the router's port forwarding and whether your ISP uses CGNAT, which blocks incoming connections.
Keep databases private
MySQL, PostgreSQL, Redis and MongoDB should normally not be reachable from the internet. If they show as open, restrict them with a firewall or security group.
FAQ
Frequently asked questions
Why can I only pick some ports?
To keep the tool from being used for port scanning, it checks one common service port at a time and is rate limited.
Port 25 is filtered. Is my mail server broken?
Many home and cloud providers block outgoing and incoming port 25. Use 587 for sending from clients, and ask your provider about port 25 for a mail server.
Is UDP supported?
No. UDP has no handshake, so an open UDP port cannot be confirmed reliably from outside.
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