Maintained by: NLnet Labs

[Unbound-users] forwarders problem

Wouter Wijngaards
Fri Jul 11 08:27:28 CEST 2014


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Hi Will,

On 07/11/2014 01:07 AM, Will Yardley wrote:
> I'm setting up Unbound for a new group of mail systems. The systems
> have rbldnsd running on port 3768. I'm having trouble configuring
> the forwarders statements. Additionally, uncached queries (whether
> to the local rbldnsd or to external DNS servers) seem to take a bit
> of time.
> 
> This is the default unbound RPM for RHEL6: 1.4.21.1.el6
> 
> main pertinent performance related configs are: server: 
> num-threads: 16 outgoing-range: 8192 so-rcvbuf: 4m so-sndbuf: 4m 
> msg-cache-slabs: 16 num-queries-per-thread: 4096 rrset-cache-size:
> 100m rrset-cache-slabs: 16
> 
> (system has 2x 8 cores @ 2.60 GHz, 15k disks in RAID 10).
> 
> My config lists the forward address and alternate port as so (I've
> tried changing the indenting, putting double-quotes around the
> forward-addr statement, etc.).
> 
> # tail -4 /etc/unbound/unbound.conf forward-zone: name:
> "zen.spamhaus.org." forward-addr: 127.0.0.1 at 3768

You need to set do-not-query-localhost: no  so that unbound can send
queries to 127.0.0.1.

Best regards, Wouter


> Even though the forwarder seems to be listed (list_forwards doesn't
> seem to print the alternate port information even when it's
> configured and working: see below): # unbound-control list_forwards
>  zen.spamhaus.org. IN forward: 127.0.0.1
> 
> I get SERVFAIL when trying to do a lookup: # dig @localhost
> 2.0.0.127.zen.spamhaus.org
> 
> ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.23.rc1.el6_5.1 <<>> @localhost
> 2.0.0.127.zen.spamhaus.org ; (1 server found) ;; global options:
> +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status:
> SERVFAIL, id: 54375 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0,
> AUTHORITY: 0, ADDITIONAL: 0
> 
> ;; QUESTION SECTION: ;2.0.0.127.zen.spamhaus.org.	IN	A
> 
> ;; Query time: 0 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;; WHEN:
> Thu Jul 10 15:50:55 2014 ;; MSG SIZE  rcvd: 44
> 
> However, the alternate port can resolve it quite quickly: # time
> dig @localhost -p 3768 2.0.0.127.zen.spamhaus.org +short 127.0.0.2 
> 127.0.0.10 127.0.0.4
> 
> real	0m0.005s user	0m0.000s sys	0m0.003s
> 
> 
> However, if I add the forwarder using unbound-control, it then
> works, however, the query time is quite long:
> 
> # unbound-control forward_add zen.spamhaus.org 127.0.0.1 at 3768 ok
> 
> # unbound-control list_forwards zen.spamhaus.org. IN forward:
> 127.0.0.1
> 
> # dig @localhost 2.0.0.127.zen.spamhaus.org
> 
> ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.23.rc1.el6_5.1 <<>> @localhost
> 2.0.0.127.zen.spamhaus.org ; (1 server found) ;; global options:
> +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR,
> id: 9595 ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0,
> ADDITIONAL: 0
> 
> ;; QUESTION SECTION: ;2.0.0.127.zen.spamhaus.org.	IN	A
> 
> ;; ANSWER SECTION: 2.0.0.127.zen.spamhaus.org. 300	IN	A	127.0.0.10 
> 2.0.0.127.zen.spamhaus.org. 300	IN	A	127.0.0.4 
> 2.0.0.127.zen.spamhaus.org. 300	IN	A	127.0.0.2
> 
> ;; Query time: 1029 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) ;;
> WHEN: Thu Jul 10 15:51:25 2014 ;; MSG SIZE  rcvd: 92
> 
> Any suggestions (and any performance tuning tips; I did try to
> follow http://unbound.net/documentation/howto_optimise.html) would
> be helpful. _______________________________________________ 
> Unbound-users mailing list Unbound-users at unbound.net 
> http://unbound.nlnetlabs.nl/mailman/listinfo/unbound-users
> 
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