Splunk Search

Field Extraction - Trim Existing Field

jchampagne
Path Finder

In some of our event logs, the client IP address is recorded with leading information (::ffff:). I would like to trim this data and create a new field, which I can then do a reverse dns lookup on using a scripted lookup.

I'm not looking to modify the index, I'd like all of this to happen at search time.
The field I'm looking to modify is called Client_Address and a sample value would be:
::ffff:192.168.207.88

If I use the following REX at search time, I get a new field called Client_IP that looks good:
rex field=Client_Address "(?\b\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}\b)"

However, I'd like to use props.conf so this all happens automatically. If I add the following line to my WinEventLog:Security stanza, it doesn't work.

EXTRACT-ClientIP = rex field=Client_Address "(?\b\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}\b)"

0 Karma
1 Solution

MHibbin
Influencer

Firstly you don't need the rex part that is a search command.

You should look at the props.conf spec file.

Try something like

EXTRACT-ClientIP = [:,f]*(?<ip>\d+\.\d+\.\d+\.\d+)

OR

EXTRACT-ClientIP = [:,f]*(?<ip>\d{1,3}\.\{1,3}\.\d{1,3}\.\d{1,3})

Or you can just use the Interactive Field Extractor to help with the config of the props.conf (if you do the regex in IFX and save it, it will do the file itself.

View solution in original post

MHibbin
Influencer

Firstly you don't need the rex part that is a search command.

You should look at the props.conf spec file.

Try something like

EXTRACT-ClientIP = [:,f]*(?<ip>\d+\.\d+\.\d+\.\d+)

OR

EXTRACT-ClientIP = [:,f]*(?<ip>\d{1,3}\.\{1,3}\.\d{1,3}\.\d{1,3})

Or you can just use the Interactive Field Extractor to help with the config of the props.conf (if you do the regex in IFX and save it, it will do the file itself.

MHibbin
Influencer

no worries... what's with the "b" in your regex?

0 Karma

jchampagne
Path Finder

Thanks for the help!
I ended up using the following line, which seems to work.

EXTRACT-ClientIP = (?\b\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}\b)

0 Karma
Get Updates on the Splunk Community!

Announcing Scheduled Export GA for Dashboard Studio

We're excited to announce the general availability of Scheduled Export for Dashboard Studio. Starting in ...

Extending Observability Content to Splunk Cloud

Watch Now!   In this Extending Observability Content to Splunk Cloud Tech Talk, you'll see how to leverage ...

More Control Over Your Monitoring Costs with Archived Metrics GA in US-AWS!

What if there was a way you could keep all the metrics data you need while saving on storage costs?This is now ...