[Olsr-dev] Detecting IP address collision between nodes

ZioPRoTo (Saverio Proto) (spam-protected)
Mon Sep 7 16:14:24 CEST 2009

At Ninux.org we implemented this:


as a OLSR plugin.

There is some code here:

Unfortunately Lorenzo (the author) does not read regularly this
development list and I also think he does not work with Mercurial ;)
As you can see the code in our SVN was organized as a OpenWRT package
for a OLSR plugin.

I can contact him directly at the Ninux.org meeting if you want more
information on this project.


2009/9/5 Mitar <(spam-protected)>:
> Hi!
> In our network we would like to extend our monitoring software with a
> possibility of detecting IP address collision between nodes. Does OLSR
> supports already something like this?
> As we researched OLSR does not detect this and merge nodes together
> into one node. This is understandable as it uses IP address to
> identify nodes so it cannot distinguish between them. Only nodes which
> are in a collision can detect this. In code there is a check if
> message comes from same IP address:
> ipequal((union olsr_ip_addr *)&m->v4.originator, &olsr_cnf->main_addr)
> But as I understand such message can come back to a node also in a
> normal OLSR operation when other nodes broadcast its message, can't
> it?
> So my idea is that each node would check TC messages and if it would
> see that there are TC messages which are with its IP address but which
> node has not send (like TC message that there is a peer this node does
> not know nothing about) it would know that there is some IP address
> collision going on.
> When this situation would be detected by the node (one or the other or
> both) it would have to report it to the monitoring node. Because
> routing does not work reliably for this node TCP is probably not
> possible. Even UDP could get lost on a way to the monitoring node. So
> an idea was to add a special flag to TC messages this node is sending
> around (and all other nodes distribute all over the network) which
> would say that a node which has send this message has detected an IP
> address collision. So all other nodes would know that something is
> happening and also the monitoring node could then get this
> information.
> What do you think? Any improvements to the idea? It is too
> complicated? It is too simple? Does something already exists? How
> would one implement this? Is it possible to implement it as a plugin?
> Would it be possible to add it to the official version if we make a
> patch?
> Mitar
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