Getting Data In

host:: stanza in props.conf not being honored for udp/514 data sources


I can't for the life of me get Splunk to recognize any form of host for UDP connections. As an example, I have a listener set up via inputs.conf on udp/514:

sourcetype = syslog
connection_host = dns

That seems to work fine. Now I'd like, for one host, to move to a different index and modify the sourcetype. The splunk index recognizes the host as "dhcpserver" (so DNS lookups are working - though names changed to protect the innocent).

In props.conf:

sourcetype              = syslog_dhcp
TRANSFORMS-index        = dhcp-index

REPORT-syslog           = syslog-extractions

and in transforms.conf:

DEST_KEY = _MetaData:Index
FORMAT   = net_dhcp

I've tried IP address, the FQDN, using wildcards, etc. No matter what I choose, this stanza is not processed. The sourcetype is still set to syslog, and the data is still indexed into main. I've run into other issues trying to use host-based criteria with UDP data sources. Am I not recognizing some inherent limitation of UDP or is there some other issue going on?

extract from btool --debug props list:

system     [host::dhcpserver]
system     BREAK_ONLY_BEFORE = 
system     BREAK_ONLY_BEFORE_DATE = True
system     CHARSET = UTF-8
system     DATETIME_CONFIG = /etc/datetime.xml
system     LEARN_SOURCETYPE = true
system     MAX_DAYS_AGO = 2000
system     MAX_DAYS_HENCE = 2
system     MAX_DIFF_SECS_AGO = 3600
system     MAX_DIFF_SECS_HENCE = 604800
system     MAX_EVENTS = 256
system     MUST_BREAK_AFTER = 
system     MUST_NOT_BREAK_AFTER = 
system     REPORT-syslog = syslog-extractions
system     SEGMENTATION = indexing
system     SEGMENTATION-all = full
system     SEGMENTATION-inner = inner
system     SEGMENTATION-outer = outer
system     SEGMENTATION-raw = none
system     SEGMENTATION-standard = standard
system     SHOULD_LINEMERGE = False
system     TRANSFORMS = 
system     TRANSFORMS-index = dhcp-index
system     TRUNCATE = 10000
system     maxDist = 100
system     sourcetype = syslog_dhcp
Tags (1)


I just had this exact same problem. This is what solved it for me:

I didn't use the WRITE_META=true line though. Here's what I ended up putting in transforms.conf:

# send data from the vmware servers to the vmware index

# set data from vmware servers to vmware_syslog sourcetype

Splunk Employee
Splunk Employee

The syslog sourcetype modified the host value before it is indexed (based on the value of the host field in the syslog data). It would be nice if the Splunk UDP input processor actually added the "host::" key to the incoming event, but instead it relies on the transform (if you look in props.conf for the [syslog] stanza, you'll see TRANSFORMS = syslog-host) to set the host.

The problem is this happens at the same time you are trying to make your own index-time settings, so they can't be applied, since at that time, the host has not yet been changed. (Search time configurations are fine.)

What can you do about it? Pretty much, you'll have to base it on a source stanza, i.e., put your configs in [source::udp:514]. Note this will apply to all data coming in that port, so you may need a bunch of different transforms that use a regex on the raw data to set things right.


Splunk Employee
Splunk Employee

I was under the impression that setting sourcetype in inputs.conf takes precedence over all others. Following this line of though, if it is correct, then doesnt the sourcetype = syslog in your inputs.conf take precedence over the props.conf sourcetype = syslog_dhcp

Since splunk seems to be good at understanding that the data is syslog, could you try to remove the line sourcetype = syslog and perform a restart. What does that lead to?

PS. The index that you are trying to send the data in, already exists, correct? You cannot try to have data go to a non existing index.

0 Karma

Splunk Employee
Splunk Employee

Oh, okay, you meant in inputs, not props. Never mind.

0 Karma

Splunk Employee
Splunk Employee

This is not the case. All matching stanzas in props.conf are applied, source::, host::, and sourcetype, and if there are conflicts, source:: generally wins, followed by host::, and sourcetype is after those. setting priority on a stanza can change this order. But that's not his problem. His problem is probably that host:: is not what he thinks (and hopes) it is. It's probably just set to the indexer's default host.

0 Karma