Every network interface — wired or Wi-Fi — has a [[!wikipedia MAC address]], which is a serial number assigned to each interface at the factory by the vendor. MAC addresses are used on the local network to identify the communications of each network interface.
When MAC address anonymization is enabled, Tails temporarily changes the MAC addresses of your network interfaces to random values for the time of your Tails session.MAC address anonymization hides the serial number of your network interface, and so, to some extent, who you are, from the local network.
MAC address anonymization is enabled by default in Tails because it is usually beneficial. But in some situations it might also lead to connectivity problems or make your network activity look suspicious. This documentation explains whether to use MAC address anonymization or not, depending on your situation.
**MAC address anonymization is enabled by default for all network interfaces.** This is usually beneficial, even if you don't want to hide your geographical location.
**Using your own computer on an public network without registration**, for example a free Wi-Fi service in a restaurant where you don't need to register with your identity. In this case, MAC address anonymization hides the fact that your computer is connected to this network.
**Using your own computer on a network that you use frequently**, for example at a friend's place, at work, at university, etc. You already have a strong relationship with this place but MAC address anonymization hides the fact that your computer is connected to this network *at a particular time*. It also hides the fact that *you* are connecting to the Tor network on this network.
In some situations MAC address anonymization is not useful but can instead be problematic. In such cases, you might want to disable MAC address anonymization as instructed below.
However, as [[discussed above|doc/first_steps/welcome_screen/mac_spoofing#what-is-mac-address]], disabling MAC address anonymization makes it possible for someone to track your geographical location. If this is problematic, consider using a different network interface, like a [[USB Wi-Fi adapter|doc/anonymous_internet/no-wifi#wifi-adapters]], or moving to another network.
**Using a public computer**, for example in an Internet café or a library.This computer is regularly used on this local network, and its MAC address is not associated with your identity. In this case, MAC address anonymization can make it impossible to connect. It can even **look suspicious** to the network administrators to see an unknown MAC address being used on that network.
On some network interfaces, **MAC address anonymization is impossible** due to limitations in the hardware or in Linux. Tails temporarily disables such network interfaces. You might disable MAC address anonymization to be able to use them.
Some networks **only allow connections from a list of authorized MAC addresses**. In this case, MAC address anonymization makes it impossible to connect to such networks. If you were granted access to such network in the past, then MAC address anonymization might prevent you from connecting.
**Using your own computer at home**. Your identity and the MAC address of your computer are already associated to this local network, so MAC address anonymization is probably useless. But if access to your local network is restricted based on MAC addresses it might be impossible to connect with an anonymized MAC address.