Using Splunk to analyze firewalls, how can I detect attackers who are doing IP spoofing attacks?

[btb2018]

How can I detect attackers using IP spoofing in Splunk?

I want to be able to detect this in Checkpoint and Juniper firewalls.

I presume a standard search operation would work, but how is anti-spoofing reported?

Thanks

[mydog8it · Accepted solution]

I do not have Checkpoint experience, but here is info from Checkpoint's website:
Logs shows that traffic is dropped with "message_info: Address spoofing" in the "Information" field.
These logs appear for inbound packets on the external interface of Security Gateway, although these packets were received from the network that belongs to the same external interface.

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[btb2018]

The aim here is to use Splunk to analyse firewalls.
The requirement is to use Splunk to see if any IP spoofing attacks have occurred.
Using index=checkpoint-opsec I am able to, for example, analyse the logs but which value in Checkpoint\ Juniper represents a spoofing attack or drop due to anti-spoofing on the firewall?