Unix app: interfaces sourcetype appears to be broken

[cmeo]

Splunk 4.2.1

I have various servers I'm monitoring, and I'm getting strange results for servers which have more than one interface, specifically virtual interfaces of the type eth0:1 etc.

I have made one modification to the shipped version of the UNIX app in local/props.conf:

[interfaces]
KV_MODE=multi

Without this, the sourcetype doesn't seem to work at all in our installation. With it, some hosts with many interfaces are being reported correctly, others are not. Anyone seen this before and know how to fix it? I see that SHOULD_LINEMERGE=false
is set in the default config, along with linebreaker etc. and I would have thought this should be enough. But it isn't.

Adding an image to this question seems to be broken too.

[cmeo]

I was able to get the results I wanted with this incantation:

 sourcetype=interfaces | multikv forceheader=1 | dedup MAC 

I can't see how to do this in props or transforms so I'm using saved searches.

Since I can't add a screenshot illustrating the problem (tried png, gif, jpg, results above), I can only say that in our installation splunk seems to be unable to extract fields properly when interfaces.sh returns virtual interfaces as well as physical ones, and looking at the UNIX app code and scripts I don't really understand why.