Check if a TCP port is open on any host instantly. No signup required.
A TCP port is a numbered endpoint (1 -- 65535) on a networked device that identifies a specific process or service. When you connect to a website, your browser communicates with the server through port 443 (HTTPS) or port 80 (HTTP). Servers use ports to route incoming traffic to the correct application -- a web server, database, SSH daemon, or mail service.
Checking whether a port is open tells you if the service behind it is reachable from the outside. This is essential for debugging connectivity issues, verifying firewall rules, and confirming that deployments are live.
| Port | Protocol | Typical Use |
|---|---|---|
| 22 | SSH | Secure shell access to servers |
| 80 | HTTP | Unencrypted web traffic |
| 443 | HTTPS | Encrypted web traffic (TLS/SSL) |
| 3306 | MySQL | MySQL / MariaDB database |
| 5432 | PostgreSQL | PostgreSQL database |
| 6379 | Redis | Redis in-memory data store |
| 27017 | MongoDB | MongoDB NoSQL database |
| 8080 | HTTP-Alt | Alternative HTTP / dev servers |
| 25 | SMTP | Email sending |
| 53 | DNS | Domain name resolution |
If the port checker reports a port as closed, consider the following:
systemctl status or docker ps.Any TCP port from 1 to 65535.
It means the host is accepting TCP connections on that port. A service is listening and ready to respond to incoming requests.
80 (HTTP), 443 (HTTPS), 22 (SSH), 3306 (MySQL), 5432 (PostgreSQL), 6379 (Redis), 27017 (MongoDB).
Common reasons include a firewall blocking the connection, the service not running on the server, or the hostname/IP being incorrect.
Yes, Valpero offers TCP port monitoring with alerts. Set up 24/7 monitoring and get notified instantly via Telegram, Slack, or email when a port goes down.
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