How to scan your local network for connected devices on macOS
· Trystero Montevideo · 10base-t interactive
You can list the devices on your local network from a Mac in several ways, and which one you want depends on how much you need to know about each device.
What macOS gives you out of the box
macOS ships with the pieces you need for a rough answer. Open Terminal and run:
arp -a
That prints the ARP table: the IP and MAC address of every device your Mac has recently exchanged traffic with. It is fast and requires nothing extra, but it only lists devices your Mac has already talked to, and it gives you no names, just addresses.
To populate the table first, ping the broadcast address for your subnet, wait a moment, then read the table again:
ping -c 3 192.168.1.255
arp -a
Bonjour fills in some of the gaps. dns-sd -B _services._dns-sd._udp browses the
services devices advertise about themselves, which is how you learn that
something at 192.168.1.42 calls itself a printer.
These tools answer "what addresses are in use". They do not answer "what is that thing", which is usually the question you actually have.
Where a scanner earns its place
A dedicated scanner sweeps the subnet rather than waiting for traffic, and then tries to identify what it found: resolving hostnames, matching the MAC address prefix against the IEEE vendor registry to name the manufacturer, and reading Bonjour advertisements. The result is a list of devices with names and manufacturers rather than a column of numbers.
IP Scanner does this on macOS, iOS and visionOS. It keeps a persistent record of the devices it has seen, so you can name them yourself, and it will tell you when something new appears on the network, which is the practical way to notice a device that should not be there.
Frequently asked questions
Does macOS have a built-in network scanner?
Not a graphical one, but it has the underlying tools. arp -a in Terminal lists
the IP and MAC addresses of devices your Mac has recently communicated with, and
dns-sd browses Bonjour service advertisements. Neither sweeps the network on
its own or identifies devices by name.
Why does a scan show devices I do not recognise?
Most unfamiliar entries are ordinary hardware announcing itself under an unhelpful name. Smart plugs, TVs, printers, and set-top boxes often report a bare model number or nothing at all. Matching the MAC address prefix to a manufacturer usually identifies them.
Why do some devices show no MAC address?
Usually because the device is on a different subnet, reachable through a router that does not pass ARP traffic, so its MAC address never reaches your Mac.
Is scanning my own network legal?
Scanning a network you own or administer is routine and is what these tools are built for. Scanning networks you do not control is a different matter and may breach the operator's terms or local law.