topic Re: Create a field from a string in Splunk Search

Create a field from a string

evang_26 — Fri, 06 Dec 2013 13:39:40 GMT

Hi users,

I have a big string in one field from which I want to extract specific values such as user and IP address and count based by that. As a reference of my logs take a look below.

Message: The user julie connected from 127.0.0.1 but failed an authentication attempt due to the following reason: The remote connection was denied because the user name and password combination you provided is not recognized, or the selected authentication protocol is not permitted on the remote access server.

The query that I created by without success is the following:

sourcetype="WinEventLog" *remote access* *failed* | rex field=Message "The user : (?<user>[a-z].*) connected from (?<ip>[1-9].*) but.*$"  | table user, ip

Do you have any suggestions??
Thanks in advance!

Re: Create a field from a string

tgow — Fri, 06 Dec 2013 13:58:28 GMT

The regex needs to look something like this:

^\w+\s+user\s+(?<user>\S+)\s+connected\s+from\s+(?<ip>\S+)\s+

So the search will be:

sourcetype="WinEventLog" remote access failed | rex field=Message "^\w+\s+user\s+(?<user>\S+)\s+connected\s+from\s+(?<ip>\S+)\s+"  | table user, ip

The capital "\S+" tells regex to grab everything that is not a space. You user names might have numbers in them for instance and you ip address has periods.

Hope that helps.

Re: Create a field from a string

somesoni2 — Fri, 06 Dec 2013 14:11:05 GMT

The rex didn't work for me with sample data from evang_26. Updated rex which worked : "The user\s+(?\S+)\s+connected\s+from\s+(?\S+)\s+"

Re: Create a field from a string

kristian_kolb — Fri, 06 Dec 2013 14:26:02 GMT

Yep, the colon after Message is not a word character (\w).

Re: Create a field from a string

evang_26 — Fri, 06 Dec 2013 14:43:29 GMT

You guys are GREAT! Fantastic! I was quite close then. However, give me a little more insight here.

Breaking down the expression "(?\S+)" to smaller pieces, why we use the "?" ? I know that this is used so as to define an optional previous character. However this is not the case here.

As for the "" obviously that's the way to create the field, so that's fine!

I appreciate your answear, again!

Re: Create a field from a string

evang_26 — Fri, 06 Dec 2013 14:43:54 GMT

You guys are GREAT! Fantastic! I was quite close then. However, give me a little more insight here.

Breaking down the expression "(?\S+)" to smaller pieces, why we use the "?" ? I know that this is used so as to define an optional previous character. However this is not the case here.

As for the "" obviously that's the way to create the field, so that's fine!

I appreciate your answear, again!