[Dnsmasq-discuss] Leopard oddity or me?

Simon Kelley simon at thekelleys.org.uk
Thu Jan 31 14:31:27 GMT 2008


B. Cook wrote:
> Hello all,
> 
> we are a PC/Mac school and since I have upgraded to leopard I see
> delays in things that I never saw before.  Windows 2k/XP boxes do not
> have this 'delay'..  We have about 20+ FreeBSD machines that we have
> around here and that 2-4 second delay logging in really is starting
> to get annoying.  Students don't really see anything wrong as they
> mostly web browse.
> 

> So at the end of this I see that I do not understand this portion of
> the log:
> 
> Jan 31 08:09:12 <local7.debug> bacula dnsmasq[6607]: query[SRV] 
> _ssh._tcp.bacula from 192.168.10.178 Jan 31 08:09:12 <local7.debug>
> bacula dnsmasq[6607]: config _ssh._tcp.bacula is NODATA-IPv6 Jan 31
> 08:09:12 <local7.debug> bacula dnsmasq[6607]: query[SRV] 
> _ssh._tcp.bacula.tcentral.local from 192.168.10.178 Jan 31 08:09:12
> <local7.debug> bacula dnsmasq[6607]: config 
> _ssh._tcp.bacula.tcentral.local is NODATA-IPv6 Jan 31 08:09:12
> <local7.debug> bacula dnsmasq[6607]: query[SRV] 
> _ssh._tcp.bacula.tcentral.local from 192.168.10.178 Jan 31 08:09:12
> <local7.debug> bacula dnsmasq[6607]: config 
> _ssh._tcp.bacula.tcentral.local is NODATA-IPv6 Jan 31 08:09:14
> <local7.debug> bacula dnsmasq[6607]: query[A] bacula.tcentral.local
> from 192.168.10.178
> 
> Does anyone know what this is doing?

It took me some time to work this out. The mac is making SRV requests
first, before A record requests. (See RFC2782 for info on SRV) Each one
gets a NODATA reply because of the "filterwin2k" flag. (Hence "config" -
this reply comes from local configuration.) The IPv6 is a complete
red-herring - a bug which is fixed in the next release.

> I understand the query for the A record.. but why did it take 2
> seconds for it to get me that answer?

I'm not sure about this, but I think the problem is your choice of
".local" as your private domain. .local has a special meaning for mDNS,
and I suspect that the delay is whilst the mac is waiting for an answer
from an mDNS broadcast. It's doing SRV records, followed by mDNS,
followed by A records.

> I don't want to 'disable' something on the mac as I am trying to keep
> the machines as they come, but how can I either answer those SRV
> requests or serve the answer for the ipv4 request sooner?  I have
> tried to disable ipv6 by not building dnsmasq with ipv6 enabled.. but
> it still doesn't seem to make a difference in the time that the A
> record is finally served.

Unless you want to start configuring SRV records, I suggest to leave
that alone - what dnsmasq is currently doing, giving instant negative
answers to SRV requests, is probably what you want.


The .local stuff is more of a problem, it was really stupid of the
standards people to grab .local and not (eg) .mdns In the end, you
probably have no choice except to change all you machines to use
something else as the private domain - maybe ".private"

> Also why is 192.168.10.198 continually asking for the PTR of the 
> connected host?  I am only connected one time.  And that connection
> is sitting idle while I write this message.

No idea on that one.
> 
> Jan 31 08:09:16 <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:09:16
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:09:24
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:09:24
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:09:45
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:09:45
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:12:08
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:12:13
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:12:13
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:12:13
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 Jan 31 08:12:13
> <local7.debug> bacula dnsmasq[6607]: query[PTR] 
> 178.10.168.192.in-addr.arpa from 192.168.10.198 ^C


Cheers,

Simon.




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