Hello and thanks for your report.
How did you install the minidlna package? It does not seem to be shipped with
Leap 42.3. What did you do to configure SuSEfirewall2 to open the port 8200?
As far as I can see it the behaviour of SuSEfirewall2 is according to
documentation:
> # When set to "yes", packages that got accepted and are considered
> # 'critical' will be logged. Such packets include for example tcp
> # connection requests, rpc connection requests and forwarded pakets.
> #
> # Set to "no" for on systems with high traffic
> #
> # defaults to "no" if not set
> #
> FW_LOG_ACCEPT_CRIT="yes"
So it seems the meaning of "critical" may be different than what you expect.
Critical here means that any TCP connection that is initiated from the outside
and gets accepted will be logged.
Disabling this option should keep your logs clean.