stretch, 9.7
I've duckduckgo'd for two days, but there seems to be no definitive answer as to how networking is supposed to be configured in stretch.
debian.org's link to "The Debian Administrator's Handbook" is for version 8, and talks about deprecated tools like ifup/down, which aren't even installed by default on stretch.
I've got a very minimal install of stretch. I used the network install .iso, and when I got to the "tasksel"-equivalent screen, I unchecked everything except the bottom-most "Standard system tools" (or whatever it says).
When I boot into my system, it works as expected; I can ping
google.com and 8.8.8.8, apt install more packages, etc.
But in trying to convert to a static address (by editing /etc/network/interfaces), and then try to restart the network ("ip link set dev enp0s3 down", then "...up") subsequent networking results in name resolution complaints or "network not available" complaints. Nor do any of the other methods I've tried work - "service network restart", "systemctl restart networking", "systemctl restart systemd-networkd", "/etc/init.d/networkng stop" then "...start".
I try a reboot. Still no go.
So I restore my interfaces file to DHCP, and reboot, and all is well. Until... I try to stop/start networking just to see if I can, using any of the methods above. A simple "if ... down" followed immediately by an "if ... up", without changing a thing between the two, results in the same error messages I had earlier, until I reboot.
btw, NetworkManager (network-manager) is not installed.
So, two questions:
1) Why can't I restore my networking after I stop it? How do I restore networking?
2) What is the canonical current method in 2019 to [semi-]manually configure networking in stretch? And is it documented anywhere? (My two days of searching leads me to think "no". Or my google-fu really sucks.)
Thanks!