Re: DNS problem
Mark.Andrews_at_isc.org
Date: 02/02/04
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To: Kenneth W Cochran <kwc@TheWorld.com> Date: Tue, 03 Feb 2004 07:28:29 +1100
> >Date: Sun, 1 Feb 2004 12:36:27 -0800 (PST)
> >From: Don Lewis <truckman@freebsd.org>
> >To: kovacspeter2@freemail.hu
> >Cc: freebsd-stable@freebsd.org
> >Subject: Re: DNS problem
> >
> >On 1 Feb, Kovács Péter wrote:
> >> Hello,
> >>
> >>> Which server in your organization is acting as a DNS
> >>> server?
> >> The Windows...
> >>
> >>> If you only have one network card in your FreeBSD box...
> >> Yes, I only have one.
> >>
> >>> This could be why you only see this kind of traffic with one IP address.
> >> Is there a way to fix this?
> >
> >Something on your FreeBSD box is sending DNS queries to your Windows box
> >and is timing out its query and closing the socket it used to send the
> >query before the Windows box returns its response. Because you have
> >net.inet.udp.log_in_vain enabled, your FreeBSD box logs the arrival of
> >the DNS response packet because there is not a UDP socket listening on
> >the port that the response is being returned to.
> >
> >About all you can do to turn off these messages is to turn off
> >udp.log_in_vain. As a substitute you could log unexpected packets using
> >one of the firewall packages on FreeBSD, which would allow you to ignore
> >packets coming from port 53 on your DNS server.
>
> I get similar messages, viz:
>
> Feb 2 09:16:59 <kern.info> localhost /kernel: Connection attempt to UDP 192.
> 168.0.1:3826 from 192.168.0.1:53
> Feb 2 09:17:39 <kern.info> localhost /kernel: Connection attempt to UDP 192.
> 168.0.1:3827 from 192.168.0.1:53
> Feb 2 09:20:28 <kern.info> localhost /kernel: Connection attempt to UDP 192.
> 168.0.1:3853 from 192.168.0.1:53
> Feb 2 09:20:33 <kern.info> localhost /kernel: Connection attempt to UDP 192.
> 168.0.1:3854 from 192.168.0.1:53
> Feb 2 09:20:43 <kern.info> localhost /kernel: Connection attempt to UDP 192.
> 168.0.1:3855 from 192.168.0.1:53
> Feb 2 09:21:01 <kern.info> localhost /kernel: Connection attempt to UDP 192.
> 168.0.1:3856 from 192.168.0.1:53
>
> Sysctl log_in_vain is is set for both tcp & udp.
>
> It has been like this for ages and so far I can find
> neither an explanation as to why, no a way to fix it
> (assuming it is some kind of breakage/misconfiguration).
> OS is 4.9-stable as of 15 January, 2004.
Your resolver asks the same question multiple times to multiple
servers. It closes the socket after it gets the first answers.
It is *normal* to receive answers from the other server after
the first answer.
It is also *normal* to receive answers late if the nameserver
cannot resolve the answer. In this case it sends SERVFAIL to
say that it is giving up. Usually the client has timed-out
and closed the socket before that has happened.
> There is indeed a Windows box at 192.168.0.2, but DNS is on
> the FreeBSD machine, configured as cache-only (supposedly;
> could be something not quite correct in that config...)
>
> There are 2 network interfaces and the syslog indicates
> (I think correctly) named listening on both of them when it
> starts. 192.168.0/24 is on an internal interface/network;
> the external interface gets its ip-address from the ISP
> via DHCP.
>
> What I'd like to do is 1. fix any errors/misconfigurations
> that might be causing those messages and 2. keep the
> cache-only nameserver, and have it run/query efficiently.
>
> Any ideas/suggestions/suggested reading?
>
> Thanks,
>
> -kc
> _______________________________________________
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-- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: Mark.Andrews@isc.org _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"
- Previous message: Zsolt Bognar: "Re: 4.9 doesn't answer."
- In reply to: Kenneth W Cochran: "Re: DNS problem"
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