for example if a miner have a unique hardware serial number (Unchangeable through flashing of Nand flash or downloading new firmware), can we track the wallet of each miner in time period?
There is no such feature, you need to make your own, and it will cost you a LOT. You need to hire someone to write a piece of code that logs the miners' logs somewhere safe only you have access to, or that same person might be able to modify the firmware so that it locks the mining pool (like what most viruses do), you can also prevent them from installing a firmware by requiring a signature.
You can seal the sdcard holder so that you know if anyone touches it, because disabling the scard flash means you need to disable the bootloader on the control board, which means, you will lock everyone including yourself out of that miner and you will never be able to flash different firmware.
But if your guys have the time to flash a different firmware, mine to their wallet for a while, and then install a different firmware, all of that while using a Sdcard, then nobody can fix that on a software level, it will be a lot easier to hire someone else who watches over your employees.
This is also hard to fix on a network level (but a lot cheaper )because if they use the same mining pool you use, then nothing on the network side can be done, unless you use a mining proxy, and here is how I picture it.
A mining proxy sits on a PC that nobody but you has access to.
All miners mine to that proxy.
Your router's firewall is configured to drop every packet that isn't coming from or going to the IP address of the PC that has the proxy running.
This way even if they change the pool settings, the pool will be "dead" and the miner won't connect, they have to connect to the proxy, and since they don't have access to the proxy, the proxy will connect to your pool with your worker only.
of course, they can bypass all of this if they have access to the router, they can just bring their own router and bypass the firewall, so maybe put it in a safe? but really, if you are worried about physical intervention happening on your farm -- you need to hire better people or hire other people to watch those people over CCTVs (to ensure they don't change the router for anything like that)
