Группы прав MyChat: "Просмотр информации", "MAC адрес"
A rule for viewing MAC addresses of users' local network interfaces. If a user have several online devices, then all of them will be displayed. Only one local network interface is displayed, the one that operates connection to MyChat Server
If necessary, use the filter for MAC addresses on the server to block one or several devices.
Note that you can change a device MAC address if you have enough rights in the operating system, that is why it is not very reliable identifier unlike, for example, HardwareID.
Also, remember that you can't obtain MAC address in WEB clients.