How to Use an IP Address to Find a MAC Address

TCP/IP networks track IP addresses and MAC addresses

What to Know

  • Ping the device you want to find a MAC address for using the local network address.
  • Enter the ARP command with a "-a" flag.
  • Look for the IP address in the results. The Mac address is next to the IP address.

This article explains how to find a MAC address with an IP address using the command line utility ARP. It also covers additional information about checking your router's connection data for an IP address.

How to Use ARP to Find a MAC Address

In Windows, Linux, and other operating systems, the command line utility ARP (Address Resolution Protocol) shows local MAC address information stored in the ARP cache. However, it only works within the small group of computers on a local area network (LAN), not across the internet.

ARP is intended to be used by system administrators, and it is not typically a useful way to track down computers and people on the internet.

TCP/IP computer networks use both the IP addresses and MAC addresses of connected client devices. While the IP address changes over time, the MAC address of a network adapter always stays the same.

Using ARP, each local network interface tracks both the IP address and MAC address for each device it has recently communicated with. Most computers let you see this list of addresses that ARP has collected.

Here is one example of how to find a MAC address using an IP address.

  1. Start by pinging the device you want the MAC to address for. Use a local address. If your network is 10.0.1.x, use that number to ping. For example:

  2. The ping command establishes a connection with the other devices on the network and shows results like this:

    Pinging with 32 bytes of data:Reply from bytes=32 time=290ms TTL=128Reply from bytes=32 time=3ms TTL=128Reply from bytes=32 time=176ms TTL=128Reply from bytes=32 time=3ms TTL=128
  3. Enter the ARP command with a "-a" flag to get a list that shows the MAC address of the device you pinged:

    arp -a
  4. The results may look something like this but probably with many other entries.

    Interface: --- 0x3 Internet Address Physical Address Type 70-3a-cb-14-11-7a dynamic​ 98-90-96-B9-9D-61 dynamic ff-ff-ff-ff-ff-ff static 01-00-5e-00-00-16 static 01-00-5e-00-00-fb static
  5. Find the device's IP address in the list. The MAC address is shown right next to it. In this example, the IP address is, and its MAC address is 98-90-96-B9-9D-61.

Person finding a MAC address via Terminal app on an iMac
Alex Dos Diaz / Lifewire

Check Your Router's Connection Data

To find the MAC address of the device connected to your router—assuming you can access the router's administrative control panel—log in and check for connected devices. Each active device, as well as recently connected devices, should list the local IP address as well as the MAC address.

There's another method used to find and change the MAC address of the computer you're currently using, which involves using the ipconfig /all command in Windows.

Why Figure Out a MAC Address?

A single device can possess multiple network interfaces and MAC addresses. A laptop computer with Ethernet, Wi-Fi, and Bluetooth connections, for example, has two or sometimes three MAC addresses associated with it, one for each physical network device.

Reasons to track down the MAC address of a network device include:

  • To set up MAC address filtering on a router to restrict local network access to only those devices whose addresses match a list of presets.
  • To determine the device's manufacturer (first half of the address) and serial number (second half of the address) for service. It's important to note that the second half of the address is not always the serial number, so it might not work for warranty requests.
  • To masquerade (spoof) the identity of a different device. MAC addressing spoofing can be used legitimately to register a home network gateway device with an internet provider. It can also have malicious intent, such as defeating the MAC address filtering feature to break into the network.

Limitations of MAC Address Lookups

It isn't usually possible to look up MAC addresses for devices outside a person's physical reach. It is often impossible to determine a computer's MAC address from its IP address alone because these two addresses originate from different sources.

A computer's hardware configuration determines its MAC address, while the network configuration it is connected to determines its IP address.

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