multiple queries on same ip/port quad
Mark Andrews
Mark_Andrews at isc.org
Mon Feb 23 20:48:09 UTC 2004
> Is DNS supposed to be able to cope with a resolver asking a nameserver
> several UDP questions in quick succession using the same
> src-ip/dest-ip/src-port/dest-port quad?
>
> I'm seeing a case where BIND 9.2.3 appears to be turning a deaf ear
> when the sender slips up and doesn't allocate a fresh src-port for
> each query.
>
> This issue turned out to be the reason why galeon and mozilla would
> hang on netbsd-current. If one clicked on a bunch of url's in quick
> succession, requesting that the pages all be put in different tabs,
> mozilla and galeon would just indicate "loading" forever. When things
> worked well (eg. the clicks were spaced far enough apart in time), the
> resolver would allocate the next ephemeral port, one number lower than
> the last one for its source port. When things got hot and heavy, the
> resolver would sometimes create the UDP socket and then switch
> threads. The next thread would also require a UDP socket, find one
> open and use it. The net effect was that several DNS queries would go
> out the same socket. Even though each DNS query had a unique DNS
> transaction id, Bind would ignore all of the queries. Now granted the
> ancient netbsd resolver could use some updating to make it
> thread-safe, but the question still remains, should Bind have been
> able to field the queries?
I suspect that you are mis-analysising the situation. There
are lots of applications (including named itself when
forwarding) that re-use the same udp socket when making
recursive queries to named without waiting for response
then de-muxing based in id.
Do you have a stateful firewall between the resolver and
named that looks at the DNS transaction id?
Mark
>
> -wolfgang
> --
> Wolfgang S. Rupprecht http://www.wsrcc.com/wolfgang/
> The above "From:" address is valid. Don't mess with it.
> Gripe to your senators about spam: http://www.wsrcc.com/spam/senators.html
>
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews at isc.org
More information about the bind-users
mailing list