Cannot share my Ethernet connection anymore after 17.04 install
Solution 1:
In Ubuntu 17.04, the dnsmasq-tools dependency has been dropped from network-manager, which results in the network sharing feature failing to work. To fix this, simply install the dnsmasq-base package.
Open Terminal and run:
sudo apt-get install dnsmasq-base
This will fix the problem. Information about the bug can be found here...