Computer networks TCP/IP used as IP addresses, so and MAC addresses connected client devices. Although the IP address changes over time, the MAC address of the network adapter always remains the same.
There are several reasons why you might want to know the MAC address of a remote computer, and this is easy to do with utilities command line, for example command line on Windows.
Why find out the MAC address?
One device can have multiple network interfaces and MAC addresses. For example, a laptop computer with connections ethernet , WiFi and Bluetooth there are two or sometimes three MAC addresses, one for each physical network device.
Reasons to track the MAC address of a network device include:
- To configure MAC address filtering on the router to restrict LAN access to only those devices whose addresses match the preset list.
- Determine the manufacturer of the device (first half of the address) and serial number (second half of the address) for service.
- Disguise (spoof) the identity of another device. MAC address spoofing can legitimately be used to register gateway home networks from an internet provider. It may also have malicious intent, such as overriding the MAC address filtering function to infiltrate the network.
MAC address lookup limits
It is usually not possible to find MAC addresses for devices that are out of human reach. It is often impossible to determine a computer’s MAC address from its IP address alone, as the two addresses come from different sources.
BUT computer hardware configuration defines its MAC − address, in while the network configuration it is connected determines its IP − address. However, if the computers are connected to the same TCP/IP network, you can determine the MAC address using ARP technology ( Address Resolution Protocol ) which is included in TCP/IP.
Using ARP, each local network interface keeps track of both an IP address and a MAC address for each device it has recently communicated with. Most computers allow you to view a list of addresses collected by ARP.
How to Use ARP to Find a MAC Address
On Windows, Linux and more operating systems command line utility arp shows information about the local MAC address stored in the ARP cache. However, it only works on a small group of computers in local network (LAN) and not via the Internet.
There is another method used for find the MAC address of the computer you are currently using which includes the use of the command ipconfig / all on Windows.
ARP is intended to be used by system administrators and is generally not a useful way to keep track of computers and people on the Internet.
Here is one example of how to find a MAC address using an IP address. Start by pinging the device you want the MAC address for:
пинг 192.168.86.45
Use the local address, so if your network is 10.0.1.x, use this number to ping.
Team ping establishes a connection with another device on the network and should show this result:
Пинг 192.168.86.45 с 32 байтами данных:
Ответ от 192.168.86.45: байт = 32 время = 290 мс TTL = 128
Ответ от 192.168.86.45: байт = 32 время = 3 мс TTL = 128
Ответ от 192.168.86.45: байт = 32 время = 176мс TTL = 128
Ответ от 192.168.86.45: байт = 32 время = 3мс TTL = 128
Use the following arp command to get a list that shows the MAC address of the device being tested: