Open Port Checker
Test if common network ports are open on any host. Select predefined ports or add custom ones.
Select Ports
Browser-based port checking has limitations. Only HTTP/HTTPS ports can be reliably tested from the browser. Non-HTTP ports may show as "closed" or "filtered" even if they are open. For comprehensive scanning, use a dedicated tool like nmap.
What are Network Ports?
Network ports are virtual endpoints for communication. Each port number (0-65535) identifies a specific process or service. Well-known ports (0-1023) are reserved for standard services like HTTP (80) and HTTPS (443).
Open vs Closed vs Filtered
Open means a service is listening and accepting connections. Closed means the port is reachable but no service is listening. Filtered means a firewall is blocking the probe.
Security Implications
Open ports expose services to the network. Unnecessary open ports increase the attack surface. Regular port scanning helps identify misconfigured firewalls and unintended service exposure on your servers.
How to Use Open Port Checker
The Open Port Checker tests whether specific TCP ports are open and reachable on a target host. Verify that your firewall rules are working correctly, confirm services are listening on expected ports, and identify potentially exposed services. This is a fundamental tool for network troubleshooting and security hardening.
Open the Port Checker Tool
Navigate to the Open Port Checker from the cybersecurity tools menu. The tool provides fields for entering a target host and the ports you want to test.
Enter the Target Host
Type the hostname or IP address of the server you want to scan. You can enter a domain name like example.com or a direct IP address.
Specify Ports to Check
Enter one or more port numbers to test. Common ports include 80 (HTTP), 443 (HTTPS), 22 (SSH), 3306 (MySQL), 5432 (PostgreSQL), and 3389 (RDP).
Run the Port Check
Click the check button to test each specified port. The tool attempts a TCP connection to each port and reports whether it is open, closed, or filtered.
Review the Results
Examine the status of each port along with the associated service name. Open ports indicate running and accessible services; closed or filtered ports suggest firewall rules or stopped services.
Common Use Cases
Firewall Rule Verification
Confirm that firewall rules are correctly blocking or allowing traffic on specific ports after making configuration changes to your network security.
Service Availability Checks
Verify that critical services like web servers, databases, and SSH are listening on their expected ports and accessible from outside the network.
Security Hardening Audits
Scan your servers for unnecessarily open ports that could be exploited by attackers, and close or restrict access to any that are not required.
Troubleshooting Connection Issues
Determine whether connection failures are caused by a closed port, a firewall rule, or an application-level issue by verifying port accessibility first.
Pro Tips
- -Only scan hosts you own or have explicit permission to test. Unauthorized port scanning may violate laws and terms of service.
- -An open port is not inherently dangerous, but unnecessary open ports increase attack surface. Close any ports that do not need to be publicly accessible.
- -If a port shows as filtered rather than closed, a firewall is likely dropping packets silently instead of rejecting the connection.
- -Check common database ports (3306, 5432, 27017) to ensure they are not accidentally exposed to the public internet.
- -After applying firewall rule changes, use this tool to verify the rules are working as expected before considering the change complete.
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