I have set up two network discovery rules networks to test if they will be scanned simultaneously. Both the logged output of the discoverer thread (zabbix_server --runtime-control log_level_increase=discoverer) and the output of tcpdump shows me that each of those networks is scanned sequentially. This is not good because I have tons of /24 networks and I need them scanned independently.
Is there a way to mitigate this somehow?
From the documentation:
Zabbix periodically scans the IP ranges defined in network discovery rules. The frequency of the check is configurable for each rule individually.
Note that one discovery rule will always be processed by a single discoverer process. The IP range will not be split between multiple discoverer processes.
You should reconfigure the number of discovery processes (StartDiscoverers) in your zabbix_server.conf from 1, which is the default, to a higher value.
The right value depends on how many C class you need to scan, the frequerncy of the scan and the response speed of the scan itself.