Check if a single TCP port is open or closed on any host.
Server-assisted public lookup
Common ports
Host
Port
Service
Response
| Port | Protocol | Service |
|---|---|---|
| 21 | TCP | FTP |
| 22 | TCP | SSH |
| 23 | TCP | Telnet |
| 25 | TCP | SMTP |
| 53 | UDP | DNS |
| 80 | TCP | HTTP |
| 110 | TCP | POP3 |
| 143 | TCP | IMAP |
| 443 | TCP | HTTPS |
| 465 | TCP | SMTPS |
| 587 | TCP | SMTP-TLS |
| 993 | TCP | IMAPS |
| 995 | TCP | POP3S |
| 3306 | TCP | MySQL |
| 3389 | TCP | RDP |
| 5432 | TCP | PostgreSQL |
| 6379 | TCP | Redis |
| 8080 | TCP | HTTP Alt |
| 8443 | TCP | HTTPS Alt |
| 27017 | TCP | MongoDB |
The Port Checker tests whether a specific TCP port on a remote host is open and accepting connections. This is useful for verifying that web servers, database servers, email servers, and other services are accessible from the internet, and for diagnosing firewall or network configuration issues.
Common ports: 80 (HTTP), 443 (HTTPS), 22 (SSH), 21 (FTP), 25/587 (SMTP email), 3306 (MySQL), 5432 (PostgreSQL), 3389 (RDP). If a port shows as closed when it should be open, the service is not running, a firewall is blocking it, or the port is correctly filtered for security.
Enter a hostname or IP address and a port number (1 - 65535), then click Check Port. The tool attempts a TCP connection and reports whether the port is open (connection accepted), closed (connection refused), or filtered (no response, likely firewall-blocked).
Use the common ports quick-select buttons to test standard service ports without typing port numbers manually.