I guess you both haven't read the documentation. In ifupdown mode, guessnet expects /etc/network/interfaces to be fed on its stdin. That's why you think it hangs — as you haven't supplied any input to it.
I guess you both haven't read the documentation. In ifupdown mode, guessnet expects /etc/network/ interfaces to be fed on its stdin. That's why you think it hangs — as you haven't supplied any input to it.