What's the best software for SSH?
I have used Putty, but I couldn't create any folders, permission denied and su is a not known command
For Windows, Putty is a pretty good SSH client.
You might also like to install WinSCP.
It's not the responsibility of SSH client for creating folder or have su command.
You'll need to know the id of the ssh user and see why there's the "permission denied" error.
Do you know what file it is that controls powerdown, so that I can make it reboot on every power failure, even if I shut down the drive via the button?
e.g. make the button or web interface power down the device, but when the power gets connected, the device thinks there was a powercut and boot up.
What file controls that as I am a linux newbie