Blog
Guides, tips, and tutorials for Mac port monitoring and network diagnostics.
Port Forwarding on Mac: Router, Firewall, and How to Verify It Worked
Port forwarding on Mac requires two separate steps: configuring your router and configuring macOS. Here's how to get both right and confirm the port is reachable.
Mac Network Monitor: 4 Tools for 4 Different Questions
Activity Monitor, Portie, Little Snitch, and Wireshark each answer a different network question on Mac. Here's how to pick the right one for what you're trying to do.
How to List All Open Ports on Mac
Three ways to list every open port on your Mac: lsof, netstat, and a GUI. Includes commands for TCP, UDP, and filtering by process or port number.
Port 3000 Already in Use on Mac: How to Find and Free It
Getting EADDRINUSE on port 3000? Here's how to find what's holding the port and kill it, with or without Terminal.
How to See Which App Is Using a Port on Mac
macOS won't tell you which app owns a busy port. Here's how to find out with lsof and a dedicated GUI tool.
What Is Using Port 5000 on Mac? (It's AirPlay Receiver)
macOS Monterey and later reserve ports 5000 and 7000 for AirPlay Receiver. Here's how to confirm it and fix the conflict with your dev server.
Kill a Port on Mac: Free Any Port With One Command
Kill any port on Mac with one Terminal command. Find the PID with lsof, terminate with kill -9, or use a one-liner that does both steps at once.
macOS Network Utility's Port Scanner Is Gone. Here Are Your Options.
Apple removed Network Utility in macOS Big Sur. Here's what to use instead for scanning ports on a Mac, with and without the Terminal.
Common Ports and What They're Used For
A practical reference for common TCP and UDP port numbers: web, SSH, email, databases, dev servers, and macOS-specific ports.
What Are Ephemeral Ports? Why Your Mac Has So Many Open
Open a port monitor on macOS and you'll see dozens of ports in the 49152-65535 range. Here's what they are, why they exist, and whether to worry.