Creating a custom where command

joepjisc — Wed, 25 Nov 2020 18:42:01 GMT

Hi,

I'm new to creating custom search commands, and haven't been able to understand the examples in the SDK repo on GitHub, if someone can point me to or provide a step by step guide to achieve the below that'd be really appreciated.

Problem: I need to filter my results to only include events where a field (cidr) is a subnet of a range entered on a dashboard ($search_cidr$).

As the builtin cidrmatch(CIDR, IP) only works with an IP and a CIDR range, I don't beleive I can do this natively, so I'm thinking a custom where command is the way to go, so I can do something like this in SPL:

| from datamodel:mymodel
| where SubnetOf(cidr, "$search_cidr$")

I've written a basic Python function in my apps bin directory to do the comparison, it takes either (IP, Subnet) or (Subnet. Subnet) and returns a boolean, however I don't know how to turn this into a filter for the where command to use.

#!/usr/bin/env python3 from ipaddress import ip_network def SubnetOf(Needle, Haystack): try: Needle = ip_network(Needle) Haystack = ip_network(Haystack) return Needle.subnet_of(Haystack) except: return False

Any guidance to get me started would be great.

Re: Creating a custom where command

richgalloway — Wed, 25 Nov 2020 21:02:27 GMT

AFAIK, the where command is not extensible. You can do the equivalent with a custom command, though.

| from datamodel:mymodel | SubnetOf needle=cidr haystack="$search_cidr$" result=foo | where foo

You'll need to convert your script into a Splunk streaming command, though. See dev.splunk.com for more.

topic Creating a custom where command in Splunk Dev

Creating a custom where command

Re: Creating a custom where command