+++ This bug was initially created as a clone of Bug #1200954 +++

kismet's systemd service unnecessarily runs as root. Upstream actually warns
about it [1], since only the individual capture binaries require special
privileges, but not the main kismet daemon. However we shouldn't adopt their
recommendations verbatim, that is to install the capture binaries as
setuid-root. Instead of setuid-root, we can use more fine-grained Linux
capabilities [2].

Note there's already a submit request underway [3] with a number of systemd
hardenings. We can keep those, and additionally drop privileges.

[1]
https://github.com/kismetwireless/kismet/blob/master/packaging/systemd/README
[2] capabilities(7) setcap(8)
[3] https://build.opensuse.org/request/show/1046457