Networking Guides

Practical, in-depth guides for port forwarding, firewall configuration, and diagnosing connectivity problems.

• How to Open a Port on Your Router (Step-by-Step)

  A complete walkthrough of port forwarding: finding your router IP, creating a forwarding rule, assigning a static local IP, and verifying the port is open.

• Why Is My Port Closed? A Troubleshooting Checklist

  Work through every layer that can block a port — router, ISP, OS firewall, cloud security groups, and the application itself — with a systematic checklist.

• Common Ports List Explained

  A detailed reference of the most common TCP ports — what runs on them, why they matter, and the security considerations for leaving each one open.

• TCP vs UDP Ports: What's the Difference?

  Why TCP and UDP behave differently, why most port checkers (including this one) test TCP, and what that means for troubleshooting UDP-based services.

• How to Check Open Ports Locally on Windows, macOS, and Linux

  Command-line steps using netstat, ss, and lsof to see which ports are actually listening on your own machine before testing reachability from outside.

• Port Forwarding for Gaming Consoles

  Which ports Xbox, PlayStation, and Nintendo Switch use for multiplayer, and how to forward them correctly to fix strict NAT type issues.

• Security Risks of Open Ports (and How to Reduce Them)

  Why every open port is an attack surface, which ports carry the most risk when exposed publicly, and practical steps to reduce your exposure.

• What Is CGNAT and How Does It Affect Port Forwarding?

  What Carrier-Grade NAT is, how to tell if your ISP is using it, and what your options are if it is preventing port forwarding from working.