Online Port Scanner
Check if specific ports are open on any host. Free, fast, and secure.
What is Port Scanning?
Port scanning is a technique used to identify open ports and services available on a networked host. Every device connected to the internet communicates through numbered ports—there are 65,535 available TCP ports on each host. A port scanner sends requests to these ports and analyzes the responses to determine whether a port is open (accepting connections), closed (reachable but not listening), or filtered (blocked by a firewall).
Network administrators and security professionals use port scanning to audit their own systems, verify firewall rules, and discover unintended services that might pose security risks. Our online port scanner makes this easy—just enter a host and select the ports you want to check.
Common Ports and Their Services
| Port | Service | Description |
|---|---|---|
| 21 | FTP | File Transfer Protocol — used for transferring files between systems |
| 22 | SSH | Secure Shell — encrypted remote access and command execution |
| 25 | SMTP | Simple Mail Transfer Protocol — sending email between servers |
| 53 | DNS | Domain Name System — resolves domain names to IP addresses |
| 80 | HTTP | Hypertext Transfer Protocol — standard web traffic |
| 110 | POP3 | Post Office Protocol v3 — retrieving email from a server |
| 143 | IMAP | Internet Message Access Protocol — managing email on a server |
| 443 | HTTPS | HTTP Secure — encrypted web traffic via TLS/SSL |
| 3306 | MySQL | MySQL database server connections |
| 3389 | RDP | Remote Desktop Protocol — Windows remote desktop access |
| 5432 | PostgreSQL | PostgreSQL database server connections |
| 8080 | HTTP-Alt | Alternative HTTP port — often used for proxies and development |
Why Check Open Ports?
Security Auditing
Identify unexpected open ports that could be exploited by attackers. Regularly scanning your own servers helps you maintain a strong security posture and verify that only intended services are exposed.
Troubleshooting Connectivity
When a service isn't responding, a port scan quickly tells you whether the port is open, closed, or filtered—helping you pinpoint whether the issue is with the application, firewall, or network.
Firewall Verification
After configuring firewall rules, use a port scan to confirm they are working as expected. Ensure blocked ports are truly closed and permitted ports are accessible from the outside.
Network Inventory
Discover what services are running across your infrastructure. Port scanning helps you build an accurate inventory of active services and detect unauthorized applications.