This one has always been tricky for me, remembering which Raspberry Pi was running which version of Raspbian / Debian.
Two handy commands from this period were:
lsb_release -da

and:
hostnamectl

They overlap a little, but they are not exactly the same thing. lsb_release focuses on Linux distribution information, while hostnamectl also reports hostname and operating-system details on systems using systemd.

In other news, we hit 41 days uptime before I decided to rebuild the server using Raspbian Jessie Lite.
The smaller Lite image suited this little Raspberry Pi web-server setup much better than the larger desktop image I had been using.
Every day is a good day to rebuild!
Most of the Take Back the Darknet guide was online by then too, although it still needed plenty of refining.