Discovery scan not working on /20

The Discovery of won’t return any results.
The same thing for works fine.
Why is that?

(the logs of ospd says: queued, started, finished. No errors)

Without knowing the details on the setup / environment the best guess which is currently possible would be that the scanner host is not able to reach that subnet (e.g. missing route, other networking / environmental problems, …).

that is not the case. the network where greenbone is located is able to see all other networks. that is why the same worked fine for the (otherwise that couldn’t have worked either). Both, the and the comprise several subnets for which the network mask actually is /24. I just did not want to enumerate them all.

any other ideas, why this isn’t working for

I can see with wireshark that the ICMP ping scan for returns ICMP replies from the hosts, while it does NOT for

I do not yet understand this since from the host where greenbone is running I can successfully ping hosts in both address ranges.

So this was actually a stupid mistake on my side. The 172.20… networks were not at all covered by /20 (but the 10.20… networks were all covered by /20), I would have needed /18 but my green bone only allows /20 or longer. I now enumerated all networks as /24.

My bad.

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