[collectd] Does the network plugin (listen) ignore packets received from self?

Jesse Reynolds jesse at bulletproof.net
Tue Sep 10 02:18:27 CEST 2013

Say you have two collectd servers, c1 and c2. All client machines are sending metrics to c1, including c2. c1 is also forwarding all collectd udp packets received on to c2, by means of an iptables tee rule on c1, and a nat rule on c2 (to rewrite the destination from c1 to c2). 

My question is, when collectd on c2 receives metrics for itself via the network plugin, are they dropped? 

The reason I ask, is that I have a ruby daemon running on c2 that's sending metrics to collectd on c1. They are appearing in c1's RRD files, but not on c2's RRD files, and I find this surprising. 

If not, perhaps then it is iptables or the linux kernel which is dropping packets it's receiving from the wire with a local source address. In which case, perhaps I can remedy this by having the ruby daemon sending to the local collectd on c2 directly, in addition to c1. 

Thank you

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