Splunk Search

Index a file once, regex to match first IP address only

stefanlasiewski
Contributor

I am attempting to Index a file once from my Splunk server. The file contains a copy of syslog data.

The lines look like this:

Nov  1 00:02:08 192.168.1.100 httpd[11726]: example.org 172.16.16.16 - - [01/Nov/2011:04:03:08 -0700] "GET /foo HTTP/1.0" 301 - "-" "Wget/1.11.4 Red Hat modified"

Also see my example at http://regexr.com/?2vfiq

I want Splunk to set the Host based on a regular expression. I created the following regular expression, which matches all IP addresses on a line.

(\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b)

How can I make sure this regex only matches the first match in the line?

Tags (2)
0 Karma

MHibbin
Influencer

In response to stefanasiewski's comment on previous answer....

The <hostIP> is for defining the field name, so obviously this can be changed as per you needs, you just need to keep the <>.

This type of regex can be applied to "memory" so you don't have to type it each time (I just like the rex command because it gives the quickest return times when testing, I normally then apply it to props.conf (via the conf file, or IFX). If you have not already done so, you should read the following documentation on search time extractions.

http://docs.splunk.com/Documentation/Splunk/latest/Knowledge/Addfieldsatsearchtime

There is an index time extraction, however this is not advisable as the indexes would have to be cleaned and indexing data would have to be restarted if there was a mistake.

To apply this, you could quickly go the Interactive Field eXtractor (IFX) in SplunkWeb, and change the regex to....

\w+\s+\d+:\d+:\d+\s(?P<hostIP>\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3})

(The difference is because the IFX doesn't appear to like multiple regex capturing groups (the parentheses))

Or you could apply this to your props.conf directly, this method involves using the sourcetype of the event (modified in inputs.conf, or when you set up the inputs in SplunkWeb)...

$SPLUNK_HOME/etc/apps/<app_name>/local/props.conf:

[<syslog_sourcetype_here>]
EXTRACT-hostIP = (\w+\s+){2}(\d+:){2}\d+\s+(?P<hostIP>(\d{1,3}.){3}\d{1,3})

This should work for you (I tested it on my small sample).

If this answers you question, could you mark the answer as accepted, to help the community.

Regards,

MHibbin

0 Karma

MHibbin
Influencer

So if I understand you, you wish to create a field just for the first IP address (host IP)... I used the following search time extraction which you could modify...

source="/var/tmp/logs/syslog.log" | rex field=_raw "(\w+\s+){2}(\d+:){2}\d+\s+(?P<hostIP>(\d{1,3}.){3}\d{1,3})"

This will extract just the first field (using the timestamp as the defining point). If you still want to extract all the IP addresses you could do that as one field, and then pipe to my rex command for just the hostIP field.

Hope this answers your question.

If it does answer your question please mark the answer as accepted to help the community.

Regards,

Matt

MHibbin
Influencer

stefanlasiewski, I have added another answer in response to your questions and provide some more assistance...

0 Karma

stefanlasiewski
Contributor

Can I use this method to permanently commit these changes to the index? I don't want my users to have to type that regex over and over again.

0 Karma

stefanlasiewski
Contributor

Thanks. What is the significance of the <hostIP> field? And does it require the <> characters?

0 Karma

MHibbin
Influencer

you could probably cut this down slightly, I just thought it best to be quite exact (for the sake of a few extra characters).

0 Karma
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