Check if a network port is open, closed, or filtered on any host.
Network ports are virtual endpoints that allow different services to communicate over the internet. Each port is identified by a number from 1 to 65535. When you connect to a website, your browser uses port 443 (HTTPS) or 80 (HTTP). Other services use their own designated ports.
| Port | Service | Description |
|---|---|---|
| 20-21 | FTP | File Transfer Protocol — used for transferring files |
| 22 | SSH | Secure Shell — encrypted remote access |
| 25 | SMTP | Simple Mail Transfer Protocol — sending emails |
| 53 | DNS | Domain Name System — translating domain names |
| 80 | HTTP | Hypertext Transfer Protocol — web traffic |
| 443 | HTTPS | Secure HTTP — encrypted web traffic |
| 3306 | MySQL | MySQL database server |
| 3389 | RDP | Remote Desktop Protocol — Windows remote access |
| 5432 | PostgreSQL | PostgreSQL database server |
| 8080 | HTTP Alt | Alternative HTTP port — often used for proxies |
Open: A service is actively listening on this port and accepting connections. This is expected for services you intentionally run (like a web server on port 80/443).
Closed: The port actively rejected the connection. No service is listening, but the host is reachable. This is normal for ports you're not using.
Filtered: No response was received — a firewall or security device is likely blocking traffic to this port. The port's status cannot be determined.
A port checker is a tool that tests whether a specific network port on a computer or server is open (accepting connections), closed (rejecting connections), or filtered (blocked by a firewall). It's essential for troubleshooting network connectivity and verifying firewall configurations.
Check ports relevant to the services you run. Common ones: 80/443 for web servers, 22 for SSH, 25 for email (SMTP), 3389 for Remote Desktop, 3306 for MySQL, and 8080 for alternate HTTP. If you're troubleshooting a specific service, check the port that service uses.
A port may show as closed because no service is listening on it, your firewall is blocking connections, your ISP blocks the port, your router doesn't have port forwarding configured, or the service isn't running. Check your firewall rules and ensure the service is started.
An OPEN port has a service actively accepting connections. A CLOSED port is reachable but nothing is listening — the host actively rejects the connection. A FILTERED port gives no response, usually because a firewall is silently dropping packets.
Log into your router's admin panel (usually 192.168.1.1), find the "Port Forwarding" section, add a rule specifying the port number, protocol (TCP/UDP), and your device's local IP address. Also add a Windows Firewall or iptables rule to allow traffic on that port.