Solving the problem of spontaneously changing MAC address on Android

For the first anniversary in life, they gave their son a tablet, about which he had long dreamed. But here's the bad luck: his MAC address constantly changed randomly after each reboot of the device or turning Wi-Fi off and on. With other Android devices, I did not observe this, but here I first encountered it. Since at home the router is configured to distribute the Internet via the white list of MAC addresses, the child was left without Internet after each discharge of the tablet until it turned off (well, he could not always keep track of and feed the pet on time), and I was forced to go into the router’s config and register a new one MAC address, then reboot the router. Naturally, this could not suit us.

In search of a solution, I had to google pretty much, because basically on a given topic I came across cries for help that remained unanswered. On bourgeois forums, they generally advised handing such a tablet over to the store, because “It's illegal and it's going to cause problems with internet-connected devices all over the world.” Well, it’s clear to the Chinese comrades, instead of getting the address range by all the rules and using them in the manufactured devices, it’s easier to make the MAC address dynamically changing and not register anywhere.

In the end, I came across several ways to solve the problem. Most sane described here:
time: http://4pda.ru/forum/index.php?showtopic=512198&st=560#entry27219089 two: http://habrahabr.ru/sandbox/62871/(this method did not suit me - Android devices, nevertheless, are quite individual) and three: http://www.china-devices.com/Thread-Fix-Wifi-BT-Mac-Adress-NvRAM-error (the most affordable )

In short, the bottom line is that you need to register a new MAC address in the file / data / nvram / APCFG / APRDEB / WIFI, starting with the fifth pair of hexadecimal numbers. It is most convenient to do this by dropping it on a computer, in some hex editor, and then returning it to its place and setting read-only rights . The latter is not always emphasized, but it is important.

Since my task was not to change the MAC address, but only to prevent its spontaneous change, it was enough to remove the write permissions for the specified file (i.e. cd /data/nvram/APCFG/APRDEBandchmod 440 WIFI) Voila! After rebooting the device, the MAC address remains the same.

PS Of course, you just won’t be able to get to the treasured file: you must first install the device (this is a separate song) and install some kind of file manager that allows you to work from root. Many advise Root File Explorer, but I was more pleased to work in Terminal Emulator for Android (do not forget to enter the command first thing su).

PPS Important: you make all changes in the system at your own peril and risk! Neither the author of this article, nor the authors of the articles at the above links will be responsible for turning the device into a brick.
Important 2: Routing the device voids the warranty on it.
Important 3: If you still edit the WIFI file,do not forget to backup it first.

PPPS Yes, I almost forgot: the TurboPad 721 tablet on the MTK 8312 chipset with Android 4.2.2 on board.