How to ease your System Administration email workload with Splunk

January 7, 2011 – 23:30
Posted in Uncategorized

Systems generate a lot of email. If you’re a sysadmin, you already know this. If you work with sysadmins, then you’re to blame (ok, maybe not). In either case, dealing with system email is time consuming, and the signal-to-noise ratio is low. More often than not these emails are ignored (procmail FTW!).
Is this a good thing? No.
Why?
These emails are generated for a reason, and that reason is usually that there’s something amiss on your system. Instead of /dev/null’ing all of these useful nuggets, why not mine them with Splunk?

In this How To we’ll setup a catch-all Postfix server and use it to Splunk all of your system generated email.

Overview

Install and start Splunk.
Install and start Postifx.
Configure Postfix catch-all.
Configre your system(s) to use the Postfix catch-all.
Configure Splunk to consume the catch-all email.

Note: Splunk need not be installed on the same system as Postfix, but for the purposes of this How To, they are co-existent.

Steps

Download Splunk Here.
Postfix can be installed on Ubuntu using apt, or in FreeBSD using ports:
- Ubuntu: $ sudo apt-get install postfix -f
- FreeBSD: $ cd /usr/ports/mail/postfix; sudo make install
In Postfix’s main.cfg file:
- Set virtual_alias_domains to all hosts from which you’re going to accept mail: virtual_alias_domains = sfeserv01.splunk.com,sfeserv31.splunk.com
- Set virtual_alias_maps to your virtual alias map file: virtual_alias_maps = hash:/etc/postfix/virtual
In Postfix’s virtual_alias_map file create a catch-all alias for each host from which you’re going to accept mail:@sfeserv01.splunk.com catch-all @sfeserv31.splunk.com catch-all
In Postfix’s aliases file create a catch-all alias and redirect it to a Maildir: catch-all: /var/mail/catch-all/
Refresh aliases, rehash maps, and reload Postfix configs:$ sudo newaliases $ sudo postmap /etc/postfix/virtual $ sudo postfix reload
In Splunk’s inputs.conf file configure batch monitor of the catch-all Maildir:# $SPLUNK_HOME/etc/system/local/inputs.conf [batch:///var/mail/catch-all] interval = 300 disabled = false index = admin_mail source = admin_mail move_policy = sinkhole sourcetype = admin_mail
In Splunk’s props.conf file configure email event parsing:# $SPLUNK_HOME/etc/system/local/props.conf [admin_mail] TRUNCATE = 0 MAX_EVENTS=200000 TIME_PREFIX = Date:\s LINE_BREAKER = tacotacotacotaco BREAK_ONLY_BEFORE = tacotacotacotaco
In Splunk’s indexes.conf file configure the email index:# $SPLUNK_HOME/etc/system/local/indexes.conf [admin_mail] homePath = $SPLUNK_DB/admin_mail/db coldPath = $SPLUNK_DB/admin_mail/colddb thawedPath = $SPLUNK_DB/admin_mail/thaweddb
Restart Splunk: $ splunk restart
Now configure your system(s) to use the Postfix catch-all mail server. In Postfix this can be accomplished in main.cfg:
relayhost = mail-relay.splunk.com

Search

You can now search Splunk for system emails: index="admin_mail" ERROR
Which should return results like these:

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Greg Albrecht