Online Port Checker
Instantly check if ports are open on your server or IP address.
Complete Guide to Online Port Checking
What is an Online Port Checker?
An Online Port Checker is a powerful network diagnostic tool designed to verify the status of specific ports on a target server or IP address. It determines whether a port is OPEN (accepting connections), CLOSED (refusing connections), or FILTERED (blocked by a firewall).
Our tool acts as an external client, attempting to establish a connection to your specified host on the requested ports. This external perspective is crucial because it simulates how the outside world (including potential attackers or legitimate users) sees your network, providing a true assessment of your firewall and port forwarding configurations.
Why Use an Open Port Check Tool?
- Security Verification: Identify accidentally exposed services effectively. An open port is a potential entry point for hackers. By regularly scanning your IP, you can ensure that only essential services are accessible to the public.
- Server Configuration: Confirm that your port forwarding rules are working correctly. Whether you're setting up a Minecraft server, a web server (HTTP/HTTPS), or a remote desktop connection, our tool validates that your router or firewall is correctly passing traffic.
- Troubleshooting Connectivity: diagnosing connection issues. If users cannot connect to your application, checking the port status helps determine if the issue lies with the server application, the local firewall, or the ISP.
- Compliance Audits: Many security standards (like PCI-DSS) require regular external vulnerability scans, including port checks, to ensure data protection.
How to Use This Free Port Scanner
- Enter Target: key in the IP Address (IPv4) or HOSTNAME (domain name) you wish to scan.
- Select Ports: Choose a preset category like Server Ports (WEB, FTP, SSH), Game Ports (Minecraft, Steam), or choose Custom Ports to enter specific numbers (e.g., 8080, 3000).
- Run Check: Click the "Check Ports" button. Our high-speed scanners will instantly probe the target.
- Analyze Results: View the detailed status report. Green indicates an OPEN port, while Red indicates it is CLOSED or filtered.
Understanding Common Ports
| Port | Service | Description |
|---|---|---|
| 80 | HTTP | Unencrypted Web Traffic |
| 443 | HTTPS | Secure Web Traffic (SSL/TLS) |
| 21 | FTP | File Transfer Protocol |
| 22 | SSH | Secure Shell (Remote Access) |
| 3389 | RDP | Remote Desktop Protocol |
Totally Free & Secure
This tool is 100% free to use with no limits. We prioritize your privacy; scan results are not logged or shared with third parties. Use it as many times as you need to secure your infrastructure.
Frequently Asked Questions (FAQ)
What is the difference between "Closed" and "Filtered" ports?
A Closed Port means our scanner reached your device, but the device explicitly rejected the connection (sent a RST packet) because no application was listening. A Filtered Port (often resulting in "Connection Timed Out") means the connection request was silently dropped or blocked by a firewall before it could even reach your device.
Why does the check fail even after I set up Port Forwarding?
This is a common frustration. Common causes include:
1. Local Firewall: Windows Firewall or antivirus software on your computer might be blocking the port even if the router allows it.
2. Wrong Local IP: Your computer's internal IP (e.g., 192.168.1.5) might have changed. Use a Static IP.
3. CGNAT: Your ISP might be using Carrier-Grade NAT, which prevents port forwarding entirely.
How do I test if my Minecraft Server port (25565) is open?
First, ensure your Minecraft server is actually running. Then, enter your Public IP Address and port 25565 into our tool. If it reports "Open," players outside your network can join. If "Closed" or "Timed Out," check your router's port forwarding settings and ensure `server.properties` doesn't have a conflicting `server-ip` setting.
Can this tool check UDP ports?
This scanner is optimized for TCP Port Checking because TCP establishes a connection (handshake) that provides a definitive status. UDP ports are connectionless and often don't send a response when open, making them difficult to reliably scan over the web without specific application-layer protocols.
Does this tool work for Localhost (127.0.0.1)?
No. This is an External Network Scanner. It tries to connect to you from the outside internet. It cannot see your local loopback address (127.0.0.1) or local LAN IPs (like 192.168.x.x). To test it, you must use your public WAN IP address.
What does "Connection Refused" vs "Timed Out" mean?
Connection Refused (Error 111) usually means the IP is reachable, but nothing is listening on that port. Connection Timed Out (Error 110) usually means the request hit a "black hole"—packets were dropped by a firewall or the IP address is offline/unreachable.
Is it safe to leave ports open?
You should only open ports for services you actively use and monitor. An open port is a door into your network. If the software listening on that port has security vulnerabilities (e.g., an outdated web server), hackers could exploit it. Always use a Port Scanner to audit your network and close unnecessary ports.
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