What is a MAC address?#
Every device that connects to a network has a network card (for Wi-Fi or a cable). The manufacturer writes a 12-digit identifier on this card, like A4:5E:60:C2:1B:7F. This hardware identifier is the MAC address. The first half indicates which company made the card.
Difference from an IP#
An IP changes depending on the network you connect to, like the address of the hotel you are staying in. A MAC address is more like the device's birth certificate and is the basis of communication inside a local network. The router uses the MAC address to know which home device to deliver each packet to.
Uses#
- Access filtering: in router settings, you can let only allowed MAC addresses onto the Wi-Fi.
- IP reservation: giving a fixed IP to a specific device on the internal network.
- Identifying devices: seeing who is connected to your network.
- Public networks: some cafes or hotels tie the connection to a MAC address.
Privacy#
Because a MAC address is fixed, it can be used to track a device across locations. For this reason, modern phones usually generate a random MAC address for each network they join.
Common mistake#
MAC filtering is not complete security, because a MAC address can be spoofed. For Wi-Fi security, a strong password and proper encryption are far more effective.