On Mon, Jul 10, 2017 at 01:54:25PM +0900, 이강우 wrote: > PS: There is nothing in the log file. > The server will be stopped(hang. power is on) momentarily and no messages > will be left in the log. How about the client log? Can you crank up the client's debugging as high as possible and at least see how far it gets in the SSH exchange? A system hang like this can only be a kernel bug, I think. -- Colin Watson [cjwatson@debian.org]