All that is required for SonicWall monitoring is to enable SNMP - but this is a bit tricky to find in the management UI.
SNMP must be enabled in two different places.
- Under System->Administration->Enable SNMP (ensure this is checked.)
- Under Network->Interfaces->->Configure->Management->SNMP: ensure this is checked.
Note: The interface on which you enable SNMP is the interface from which the collector will query the firewall by SNMP, not the interfaces for which you want SNMP information. SNMP information will be returned for all interfaces.