[Dnsmasq-discuss] Logging milliseconds//Addendum

[m***@manfbraun.de]

Hi All !

I just changed some free DNS against some other free DNS
and now, I have more problems then bevore. Though I'll
extend my logging thoughs: In the DNSMasq answer is not
visible which of dns provided the answer - that makes diag
problematic.

Thanks anyway,
Manfred

-----Original Message-----
Sent: Monday, June 20, 2016 3:09 PM
Subject: Re: [Dnsmasq-discuss] Logging milliseconds
Hi,
Le Mon, 20 Jun 2016 13:13:26 +0200

Hello !
I am just facing the situation, that my dns-request needing a very
long time, and this is wether my requesting client, nor dnsmasq. It's
the provider trying my attempt to ignore his DNSs and use free DNSs,
as we have several here in Germany.
Its not a whole week gone, when I opened an issue about DNS blocking.
It was that, I have enough facts - I'll not try to write whole story
here. But at that last issue, I found me in the situation, where I
want to analyse dnsmasq's log.
DNSMASQ log output format] the relationship between a clients
request and dnsmasq's answer to it. There can be several in
progress ... From the log, you'll not see it.
Today, due to the DNS blocking story, I want to make a stats over
the log, but it contains only seconds in the timestamp, were I
wished it to have milliseconds too. Is that possible ? I cannot
find something about this.
Additionally, at best, I would fetch the output, if I start the
process by myself and pipe its output directly. Probably not
doable for me. I would write a mini program in C# ... Another
solution would be, to create a pipe in the filesystem and define
it as the logfile for the dnsmasq. I have done this, at least with
apache, it works (Apache has the charm, to be able to host
a program und pump it's output into it - but thats easy for me).
Wether or not, without milliseconds, it would be sensless.
Any help, notes and hints are very welcome !!

If you can run wireshark or even simply tcpdump on the machine that runs
dnsmasq, then you could log DNS requests and replies with accurate time
stamping. Would this be enough for you?

Thanks anyway,

Amicalement,
--
Albert.

[Albert ARIBAUD]

Hi Manfred,

Le Tue, 21 Jun 2016 17:30:13 +0200

Post by m***@manfbraun.de
Hi All !
I just changed some free DNS against some other free DNS
and now, I have more problems then bevore. Though I'll
extend my logging thoughs: In the DNSMasq answer is not
visible which of dns provided the answer - that makes diag
problematic.

Seems you started a new thread while I was answering on the previous
one.

Short answer: I would suggest that you avoid trying "this and that" as
well as ad hoc patching", and that you follow a more systematic approach
to solving your problem, by running tcpdump on the machine which hosts
your dnsmasq.

Also, you should really try and make other hypotheses than just your ISP
messing with DNS. For instance, have you tried to find out how much of
your uplink bandwidth you're using? Because if your uplink saturates,
then UDP packets sch as DNS requests might get dropped by your ISP's
modem.

Post by m***@manfbraun.de
Thanks anyway,
Manfred

Amicalement,

[m***@manfbraun.de]

Hi !

Many thanks for your investigation !!!

I'll not bother you or anyone in any way, but we may just have
different perspectives to see the problem. I just tell my
opinion about the log - noone should start to patch something.
I am also the type, which waits for distro updates ... to shy to
install from source.

My log-example was mainly to show, that DNSMasq COULD
give a better help through it logs - it was not thought to
explain the problem. That, what you asked to me, exactly
that - so I think - should answer the log ... pobably, one day.

I think, I have good control over my environment and I ensure,
if I make tests like my DNS tests, that the line is not loaded !
The log-example stems just from real-live, were countless apps
are running and different computer are up. There is, for example,
a RSS reader, which starts batch-loads for a big list of websites - just
to explain, why I do not wonder about the logfile. There is much
more, like over 20 Virusprotection solution, which updates every
hour ...

So I'll start to make a tool, which systematically answers some
(all known open/free DNS in Germany) and measure the overall
response. Will need some time, so. In the meantime, I am using
the DNS from the ISP - anyway what may cause the problem,
if I use the DNS from ISP, I never have problems at all ..... !!!

If this would not be the case, I really would also suspect
DNSMasq (indirectly), because this runs on a stonehenge
old box, with really no memory free .... I see in my syslog,
the Nagios command sometimes fail, due to not enough
memory. This cannot be fixed very fast - too many thing
on my list. But a new firewall machine is already on the
table ...

Thanks again and my best regards,
Manfred

[I hope, this "reply all" will not cause another thread ...]

-----Original Message-----
Sent: Tuesday, June 21, 2016 8:05 PM
Subject: Re: [Dnsmasq-discuss] Logging milliseconds//Addendum
Hi Manfred,
Le Tue, 21 Jun 2016 17:30:13 +0200

Post by m***@manfbraun.de
Hi All !
I just changed some free DNS against some other free DNS
and now, I have more problems then bevore. Though I'll
extend my logging thoughs: In the DNSMasq answer is not
visible which of dns provided the answer - that makes diag
problematic.

Seems you started a new thread while I was answering on the previous
one.
Short answer: I would suggest that you avoid trying "this and that" as
well as ad hoc patching", and that you follow a more systematic approach
to solving your problem, by running tcpdump on the machine which hosts
your dnsmasq.
Also, you should really try and make other hypotheses than just your ISP
messing with DNS. For instance, have you tried to find out how much of
your uplink bandwidth you're using? Because if your uplink saturates,
then UDP packets sch as DNS requests might get dropped by your ISP's
modem.

Post by m***@manfbraun.de
Thanks anyway,
Manfred

Amicalement,
--
Albert.