Network Port Checker & Simulator
Test connectivity and explore common network entry points.
What are Ports and Why Check Them?
In the world of networking, an IP address identifies a computer, but "ports" identify the specific services running on that computer. Think of an IP address as a building's street address, and ports as the individual apartment doors. Our port checker utility helps you understand which "doors" are open for business and which are locked for security.
Common Ports You Should Know
Every professional port scanner looks for "standard" ports that are assigned to specific duties:
- Port 80 (HTTP): The standard door for unencrypted web traffic.
- Port 443 (HTTPS): The secure door for encrypted web traffic. If you're reading this, your browser is using Port 443.
- Port 22 (SSH): Used for secure remote login to servers. An open port test on 22 is common for server admins.
- Port 21 (FTP): The traditional method for moving files between machines.
- Port 3389 (RDP): Windows Remote Desktop port. Finding this open on a public IP is often a security risk.
Why Browser-Based Port Scanning is Different
A standard online port checker used to be able to scan your local network, but browser developers closed this "vulnerability" to prevent malicious websites from mapping your home network. Our port checker tool uses a hybrid approach. It tests real connectivity for web-based services (80/443) while acting as a diagnostic reference for other ports, providing you with the technical context needed for network hardening.
Finding "Stealth" Ports
When a check open ports utility returns a "Timeout" or "Filtered" result, it often means a firewall is actively hiding that door. This is called "stealth mode." For home users, ensuring common ports are closed is a critical part of cybersecurity, as hackers often scan blocks of IP addresses looking for anything that responds.