The Discovery of 172.20.0.0/20 won’t return any results.
The same thing for 10.20.0.0/20 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 10.20.0.0/20 (otherwise that couldn’t have worked either). Both, the 10.20.0.0/20 and the 172.20.0.0/20 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 172.20.0.0/20?
I can see with wireshark that the ICMP ping scan for 10.20.0.0/20 returns ICMP replies from the hosts, while it does NOT for 172.20.0.0/20.
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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