[Xymon] Purple storm

[Josh Luthman]

Can you make the default to testip but specify a host to use DNS?

Josh Luthman
Office: 937-552-2340
Direct: 937-552-2343
1100 Wayne St
Suite 1337
Troy, OH 45373



On Thu, Apr 12, 2012 at 4:43 AM,  <henrik at hswn.dk> wrote:
> On Thu, 12 Apr 2012 06:27:01 +0000, "Poppy, Ben"
> <poppy.ben at marshfieldclinic.org> wrote:
>> I may have missed this in a past post, how do I apply this patch?
>
> Ah - ok, my developer-mind assumed everyone knows how to do that :-)
>
> Save the attachment to /tmp/dnstimeout.patch, then:
>
>  cd xymon-4.3.7
>  patch -p0 </tmp/dnstimeout.patch
>  make clean
>  make
>
> You can run "make install" afterwards, but a safer option would be to just
> copy the "xymon-4.3.7/xymonnet/xymonnet" binary into your Xymon "bin"
> directory, replacing the one that is already there.
>
>
>> I do test DNS for sure on servers at our DR site (many of them). The
> test
>> you suggest below, is that to simulate the purple storm?
>
> It is to simulate that your Xymon server loses connectivity to the DNS
> server on the primary site.
>
>> Should it
>> essentially turn purple if I begin dropping all packets to a few DNS
>> servers I'm testing?
>
> That is what I suspect, yes.
>
>> Would I be able to run this same iptables on my backup xymon server in
> our
>> primary site to a few servers it checks DNS against in our DR site?
> Should
>> that effectively cause the purple storm?
>
> What I'm trying to do is to simulate the situation you had which caused
> the purple storm, without actually pulling the plug and disrupting the
> network between the two sites. If I understand you correctly, then the
> purple storm happened when you lost the connection between your two
> datacenters. Since I suspect that this is related to DNS lookups taking a
> very long time with the stock 4.3.7 Xymon version, you can use iptables to
> just block traffic from Xymon to the DNS server(s) in the other datacenter.
>
>
> Regards,
> Henrik
>
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