DISCOVERs from "unkown network segment" - suppress log messages?

Christina Siegenthaler tina at ieu.uzh.ch
Tue Nov 29 08:22:59 UTC 2022


Thanks for all the ideas. Tried some stuff and ended up with this:

I added a subnet declaration for the subnet of the offending host and added „ignore booting“ to it, but no pool. This didn’t work, though, since it just changed the log messages from „unknown subnet“ to „no free leases“, but I still got them.

Since I know that the rogue client is supposed to get a fixed IP address (and which one), I added a pool to that subnet declaration containing just this one IP, plus a host declaration for the rogue client with a „fixed-address“ statement giving it the fixed IP it’s supposed to get from the other DHCP server, plus, just to be safe, an "ignore booting" statement as well.


Looks like this:


####################
# Ignore these
####################

subnet 10.65.xx.0 netmask 255.255.254.0 {
        pool { range 10.65.xx.61 10.65.xx.61;
                ignore booting; }
}

host ignore_me_1 { hardware ethernet 00:07:32:xx:xx:xx; ignore booting; fixed-address 10.65.xx.61; }

###########

And yes! Now I’m no longer getting the messages.


I’m just hoping that this configuration doesn’t mess up that subnet… getting a lot of „unkown lease“ and „no free leases“ log messages for that subnet now, replacing the „unknown subnet“ ones. I don’t see any NAKs going out, though, so I hope this should be OK. Guess I’ll find out sooner or later… 

It’s not pretty, but if that gets rid of these messages for good, I can live with it. As was mentioned - I’m processing the log each night to import some stuff into our inventory database, and if it’s filled with these crap messages, that’s not really helping.

To be honest, I had half a mind to start handing out bogus leases to that subnet, especially since the department owning the printer seems to have chosen to ignore my complaints, but as someone pointed out, this wouldn’t help my career, and I still have some years to go on ;-) As it is now, I think I have done everything to try and make sure I don’t mess up anything for them while still getting rid of the messages. Except maybe for the rogue client, but since they don’t want fix that, it’s their problem.


Tina


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