Splunk Search

Create multivalue field from single number

Motivator

For a simple example of the concept, let's consider Linux file permissions encoding of read, write and execute into a single number:
Example: "7, 5, 1"

file_access_user_code="7", 
file_access_group_code="5",
file_access_world_code="1" 

If we look at the first number, it says that the user can read (4), write (2), and execute (1): 4+2+1=7

code, attr
4, read
2, write
1, execute

So my field, file_access_user, is a multi-value field equal to (read, write, execute). Group is read and execute, and world is only execute.
My goal is for splunk to see file_access_user_code and extract the following:

file_access_user="read, write, execute", 
file_access_group="read, execute",
file_access_world="execute"

I give the chmod example as a simple representation of a much more complex table based on hexadecimal encoding of attributes into a single number. How can we tell splunk to take a lookup table with columns "code" and "description" and auto-lookup the numeric values to give multi-value fields with all encoded values listed explicitly?

0 Karma

Legend

First, I would make the table a bit easier to use - it's only 7 values (15 for hex) and it saves a lot of computational work that is not easy in Splunk:

code, attr
7,"read, write, execute"
6,"read, write"
5,"read, execute"
4,read
3,"write, execute"
2,write
1,execute

Now try this

yoursearchhere
| eval file_access_user_code= substr(file_access_string, 1, 1)
| eval file_access_group_code= substr(file_access_string, 2, 1)
| eval file_access_world_code= substr(file_access_string, 3, 1)
| lookup file_access_lookup code as file_access_user_code OUTPUT attr as file_access_user
| lookup file_access_lookup code as file_access_group_code OUTPUT attr as file_access_group
| lookup file_access_lookup code as file_access_world_code OUTPUT attr as file_access_world
| makemv delim="," file_access_user
| makemv delim="," file_access_group
| makemv delim="," file_access_world

How to do this automatically: you could make file_access_user_code, file_access_group_code and file_access_world_code into calculated fields, and then use them for the automatic lookup. However, your resulting fields will be strings, not multi-valued fields.

0 Karma