Because I am using Bionic Beaver/Ubuntu 18.04, the network settings in /etc/network/interfaces
are being ignored and the settings in /etc/NetworkManager/system-connections/'eth0'
are being used for i) static ip ii) gateway etc.
I wish to restart the sshd service every time the interface comes up. It doesn't work in the normal place /etc/network/interfaces
since I'm using Gnome. Where can I place a NetworkManager script to be run every time a specific interface comes up?