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Port Reference

Common TCP/UDP network port numbers reference

PortProtocolServiceDescription

What is Port Reference?

Port Reference is a free online tool that helps you common tcp/udp network port numbers reference. It runs entirely in your browser using client-side JavaScript, so your data stays private and never leaves your device.

When to Use

  • Troubleshooting network issues and looking up DNS or IP information
  • Learning about networking concepts like ports, protocols, and headers
  • Quick reference for network configuration and diagnostics

How to Use

Enter your input in the field above, adjust any settings if available, and click the action button. Results appear instantly—no page reload, no server wait. All processing happens locally in your browser.

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Deep Dive: How Port Reference Works

Port Reference provides instant visibility into network configuration, connectivity, and protocol details—essential diagnostic capabilities for anyone working with internet-connected systems. Network troubleshooting is notoriously difficult because problems can originate anywhere in the stack: DNS misconfiguration, routing issues, firewall rules, application-level bugs, or upstream provider outages. Port Reference helps you quickly narrow down the source of issues by providing key diagnostic data points without requiring SSH access to remote servers or installation of specialized network tools. Understanding your network environment is also critical for security—knowing what's exposed, what IP information you're leaking to services, and what ports are accessible helps you assess your attack surface and implement appropriate protections. For developers building web applications, network tools provide the ground truth needed to debug connectivity issues, verify CDN configuration, and ensure APIs are reachable from production environments.

Pro Tips

  • Check DNS from multiple locations if results seem wrong—DNS propagation can take up to 48 hours
  • Use IP lookup tools to verify your VPN or proxy is actually routing traffic correctly
  • Test port connectivity before blaming application code—firewall rules are the most common culprit

Common Mistakes to Avoid

  • Trusting a single IP lookup source—geolocation databases have varying accuracy
  • Testing connectivity only from your own machine when users are on different networks

Frequently Asked Questions

What are the most common TCP and UDP port numbers?
Essential ports include: 20/21 (FTP), 22 (SSH), 25 (SMTP), 53 (DNS), 80 (HTTP), 110 (POP3), 143 (IMAP), 443 (HTTPS), 993 (IMAPS), 3306 (MySQL), 3389 (RDP), 5432 (PostgreSQL), 6379 (Redis), and 27017 (MongoDB). A port reference lists all well-known ports (0-1023) and registered ports (1024-49151).
What's the difference between well-known ports, registered ports, and dynamic ports?
Well-known ports (0-1023) are assigned by IANA to core services like HTTP (80) and SSH (22). Registered ports (1024-49151) are for user applications like MySQL (3306) and can be registered with IANA. Dynamic/private ports (49152-65535) are temporary ports used by client applications for outbound connections.
How do I check which port a specific service or application uses?
Look up the service name in a port reference database. Common protocols have well-known defaults—web servers use 80/443, databases have vendor-specific defaults. For custom applications, check the application's config file or documentation. The port reference shows both official IANA assignments and commonly used unofficial ports.