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How to Check Open Ports on a Mac

Updated 2026-09-07  Â·  3 min read

An open port isn't automatically a problem, most Macs have a handful open for entirely ordinary reasons. The question worth answering is which ones, and whether any belong to something you don't recognize.

List every listening port

sudo lsof -i -P | grep LISTEN

LISTEN is the state that means a process is waiting for an incoming connection rather than actively talking to one, which is the definition of an open port. Each row shows the process name, the port number, and whether it's bound to localhost only or to all interfaces.

That last distinction matters more than the port number itself. A service listening on 127.0.0.1 only accepts connections from your own Mac, nothing on the network can reach it. A service listening on 0.0.0.0 or your actual network address is reachable from other devices on the same network, which is a meaningfully different exposure.

What's normal to find

None of these are exposure risks by themselves. Most sit behind the macOS application firewall anyway, which by default blocks unsolicited inbound connections to anything not explicitly allowed.

Turning the firewall on, if it isn't already

  1. System Settings, then Network.
  2. Click Firewall.
  3. Toggle it on.
  4. Click Options to review which apps are allowed to accept incoming connections.

It ships off by default on most consumer Macs, which surprises people. Turning it on blocks unsolicited inbound traffic to anything you haven't explicitly allowed, without touching the outbound connections your own apps make.

What's worth investigating

A port bound to your network address (not localhost), tied to a process name you don't recognize, especially one you didn't knowingly install, is the combination worth digging into. Search the process name before assuming the worst; a lot of legitimate background helpers have names that sound alarming out of context.

The honest baseline For a Mac that isn't deliberately running a server (Plex, a dev environment, file sharing to other machines), a healthy port list is short: a handful of Apple system services, maybe one or two apps you're actively running, almost all bound to localhost. Anything well outside that shape is worth a second look.

See listening ports with a plain-English risk badge, not raw output

CleanMachine's Port Scanner lists every listening port and flags each one Safe, Unknown or Exposed, so you're not cross-referencing process names by hand. Free to scan.

↓ Download Free & Scan

Common questions

How do I check open ports on a Mac?
Run sudo lsof -i -P | grep LISTEN in Terminal. Each result shows the process holding the port and whether it's bound to localhost only or to the network, which is the detail that determines actual exposure.
Is an open port on my Mac dangerous?
Usually not by itself. Most listening ports on a typical Mac belong to ordinary system services and are bound to localhost, meaning nothing outside the Mac can reach them. A port bound to the network and tied to an unrecognized process is the combination worth investigating.
Is the macOS firewall on by default?
No, it ships off on most consumer Macs. Turn it on in System Settings, Network, Firewall to block unsolicited inbound connections to anything you haven't explicitly allowed.
What's the difference between localhost and network-bound ports?
A port bound to 127.0.0.1 (localhost) only accepts connections from processes on the same Mac. A port bound to 0.0.0.0 or your Mac's actual network address can be reached by other devices on the same network, which is a real difference in exposure.

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