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TCP Port Connectivity Check

Test TCP port connectivity to verify if services are accessible from your location. This tool helps diagnose network connectivity issues and validate service availability.

Example Usage​

Common Ports to Test​

  • HTTP: example.com:80
  • SSH: github.com:22

Batch Testing Example​

github.com:443

TCP Port Connectivity Check

Test TCP port connectivity to check if services are accessible. Use single mode for individual tests or batch mode for multiple targets.

Browser Limitations

• HTTP/HTTPS ports (80, 443, 8080, 3000) use direct HTTP requests for best accuracy
• Other TCP ports are tested via WebSocket connections
• CORS policies may affect some test results
• Some firewalls may block WebSocket connections

Technical Notes​

Browser Limitations​

Due to browser security restrictions, there are some limitations to consider:

  • HTTP/HTTPS Ports: Works best for standard web ports (80, 443, 8080, 3000) using direct HTTP requests.
  • Other TCP Ports: Tested using WebSocket connections, which may have different behavior than native TCP.
  • CORS Policies: Some servers may block cross-origin requests, affecting test results.
  • Timeouts: Tests timeout after 5 seconds to prevent hanging connections.

Interpreting Results​

  • ✅ Success: Port is open and accepting connections
  • ❌ Failed: Port is closed, filtered, or service is not responding
  • ⏰ Timeout: Connection attempt timed out (may indicate filtering)

Best Practices​

  1. Test Common Ports First: Start with well-known ports (80, 443) to verify basic connectivity
  2. Use Batch Mode Efficiently: Group related services together for comprehensive testing
  3. Consider Network Context: Results may vary based on your network location and firewall rules
  4. Verify Critical Services: Regularly test important service endpoints for monitoring purposes

Troubleshooting​

If you encounter issues:

  1. Connection Failed: Check if the host is reachable and the service is running
  2. Timeout Issues: May indicate network filtering or slow connections
  3. CORS Errors: Normal for cross-origin requests; doesn't necessarily mean the service is down
  4. WebSocket Limitations: Some firewalls may block WebSocket connections used for non-HTTP ports

This tool is designed for quick connectivity checks and basic network diagnostics. For production monitoring, consider using dedicated network monitoring tools.