Online Port Checker

Every device connected to the internet communicates through numbered entry points known as ports. Think of an IP address as a street address and ports as the individual doors in a building -- each door leads to a different service or application. There are 65,535 available ports, and each one can be used by a different network service. For example, web traffic typically uses port 80 (HTTP) or 443 (HTTPS), while email servers listen on port 25 (SMTP) and secure shell connections use port 22 (SSH).

Port checking is the process of testing whether a specific port on a given IP address is open (accepting connections) or closed (rejecting or not responding to connections). This is an essential diagnostic tool for network administrators, developers, and security professionals. When you deploy a web server, for instance, you need to verify that ports 80 and 443 are open and accessible from the internet. Similarly, if you are troubleshooting a database connection, checking whether port 3306 (MySQL) or 5432 (PostgreSQL) is reachable can quickly narrow down the issue.

From a security perspective, open ports represent potential entry points for attackers. Each open port exposes a service that could have vulnerabilities. This is why security best practices recommend closing any ports that are not actively needed and using firewalls to restrict access to only trusted IP addresses. Regular port scans of your own infrastructure help you maintain a strong security posture by identifying unexpected open ports before attackers do.

Our port checker tool sends a TCP connection attempt to the specified IP and port. If the connection completes successfully (the TCP three-way handshake), the port is reported as open. If the connection is refused or times out within 5 seconds, the port is reported as closed. The response time indicates how long the connection took to establish, which can also help diagnose network latency issues.