[Xymon] Xymon disruption every night!

[Becker Christian]

My intention was the figure out if the network connection of the Xymon server itself has a problem…
For example, if your Xymon server is hardware, then it has a wired network interface that is connected to a network switch. That’s your link between the Xymon server and all of your other VMs and physical servers.
From my side, if you only see problems on the Xymon server, I’ld have a look at this particular switch port or the cable infrastructure to the Xymon server. Or could there be a firewall rule preventing the Xymon server accessing the DNS server?

By the way – do you have only one DNS server in /etc/resolv.conf? Did you check the logs on your DNS server? Can you issue a continuous ping to the Xymon server to see if it loses some packages in 24hours?

Regards
Christian


Christian Becker
IT-Services

Christian.Becker at rhein-zeitung.net<mailto:Christian.Becker at rhein-zeitung.net>
_________________________________
Mittelrhein-Verlag GmbH
August-Horch-Straße 28
D-56070 Koblenz
Verleger und Geschäftsführer: Walterpeter Twer
Reg.-Gericht Koblenz HRB 121
Finanzamt Koblenz Str.Nr. 22 65 10 285 2
www.rhein-zeitung.de<http://www.rhein-zeitung.de/>

Von: Xymon [mailto:xymon-bounces at xymon.com] Im Auftrag von L-M-J
Gesendet: Freitag, 29. Januar 2016 13:07
An: Xymon at xymon.com
Betreff: Re: [Xymon] Xymon disruption every night!

Problems appears on VMs and physical servers and Lan and DMZ equipments. I don't see a link between those devices :-(

Le 29 janvier 2016 09:23:14 GMT+01:00, Becker Christian <christian.becker at rhein-zeitung.net<mailto:christian.becker at rhein-zeitung.net>> a écrit :
Hi L-M-J,


can you exclude that this behavior is coming from any network device like a switch or default gateway?


Regards
Christian


Christian Becker
IT-Services


Christian.Becker at rhein-zeitung.net<mailto:Christian.Becker at rhein-zeitung.net>
_________________________________
Mittelrhein-Verlag GmbH
August-Horch-Straße 28
D-56070 Koblenz
Verleger und Geschäftsführer: Walterpeter Twer
Reg.-Gericht Koblenz HRB 121
Finanzamt Koblenz Str.Nr. 22 65 10 285 2
www.rhein-zeitung.de<http://www.rhein-zeitung.de/>


Von: Xymon [mailto:xymon-bounces at xymon.com] Im Auftrag von L-M-J
Gesendet: Freitag, 29. Januar 2016 08:57
An: Xymon at xymon.com<mailto:Xymon at xymon.com>
Betreff: [Xymon] Xymon disruption every night!


Hi,

I'm running Xymon since 6 years (4.3.17 atm) on Debian 7.8
3.2.0-4-amd64
Since 1 month now, every night, between 0h30 or 2h am at +/- 30 min,
around 30 hosts become unreachable :

Fri Jan 29 01:16:38 2016 conn NOT ok : DNS lookup failed
Unable to resolve hostname foo.bar.local
System unreachable for 3 poll periods (170 seconds)
green 0.0.0.0 is alive (0.02 ms) [<- 127.0.0.1<http://127.0.0.1>]


- Got around 500 monitored hosts and looks like the same hosts are
lost every single night.
- Those monitored hosts are not necessary on the same network, not
the same OS.
- We cross monitored the same hosts and the other monitoring tool
doesn't have report the DNS outage.
- I ran a DNS lookup every seconds on the Hobbit server several days
and it never reported a DNS outage.
- I don't have any crontab installed on the server who could disturb
Xymon.
- Nothing strange in the Xymon logs nor the server logs, no memory
leaks or CPU overloaded.
- The rest of the day, Xymon server behavior is normal.
- What I've done on the server 1 month ago ? I don't know, no system
upgrade or so.
- I had DNSMASQ acting like a cache, I disabled it : same issue
- /etc/resolv.conf is quite light : search bar.local, next line :
nameserver IP.OF.OUR.DNS.SERVER1, just like other servers

The issue could be anywhere : inside or outside the server, Xymon or
not... I have to confess, I'm running out of ideas to find the issue, is
anyone here may have some leads, I will be thankful !

Have a nice day!

--
Envoyé de mon appareil Android avec K-9 Mail. Veuillez excuser ma brièveté.
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