Is there a command or search to see which unique Cisco firewalls are sending traffic to Splunk?

[eastgrant]

Does anyone know the command or search string to see which Cisco firewalls are sending traffic to Splunk?

[jkat54]

This depends on how they send data to splunk. Is it via UDP?

Something like this should work in most cases:

index=indexName |dedup host | table host
index=indexName |dedup source | table source