Re: Bind, dnssec, udp fragmentation woes.

2009-10-05 Thread Mark Andrews

In message <1254502519.14277.16.ca...@dv6d4k1-u>, "Nicholas Wheeler" writes:
> On Fri, 2009-10-02 at 13:22 +1000, Mark Andrews wrote:
> > You really want to work out what is being blocked, EDNS?, responses
> > bigger that 512 bytes? DNSSEC? fragmented responses?  With a clean
> > path all of these should succeed but only the last one won't have
> > "tc" set.  This does a plain DNS query, a EDNS query that limits
> > the response to 512 bytes, a DNSSEC query that limits the response
> > to 512 bytes, a DNSSEC query that limits the response to something
> > that would not normally be fragmented but exceeds 512 bytes, a
> > DNSSEC query that will normally be fragmented.
> >=20
> > % dig soa se @192.36.133.107 +norec +ignore=20
> > % dig soa se @192.36.133.107 +norec +ignore +bufsize=3D512
> 
> The above two work, the below four do not work (connection timed out; no
> servers could be reached).=20
> 
> (note: I replaced se with my domain.tld, and the @ with my server).
> 
> 
> > % dig dnskey se @192.36.133.107 +norec +ignore +bufsize=3D1200
> > % dig dnskey se @192.36.133.107 +norec +ignore +bufsize=3D512 +dnssec
> > % dig dnskey se @192.36.133.107 +norec +ignore +bufsize=3D1200 +dnssec
> > % dig dnskey se @192.36.133.107 +norec +ignore +bufsize=3D4096 +dnssec
> >=20
> > Mark
> 
> Thanks for the help, but I don't know what this implies, other than
> nothing dnssec-related with udp works ;)

It means you have a device in the path that doesn't like UDP answer bigger
that 512 bytes *and* also doesn't like having "DO" set.

; <<>> DiG 9.3.6-P1 <<>> dnskey se @192.36.133.107 +norec +ignore +bufsize=512 
+dnssec
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 52624
;; flags: qr aa tc ad; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
;; QUESTION SECTION:
;se.IN  DNSKEY

;; Query time: 334 msec
;; SERVER: 192.36.133.107#53(192.36.133.107)
;; WHEN: Tue Oct  6 09:16:58 2009
;; MSG SIZE  rcvd: 31

Now what you need to do is use a packet sniffer to see which devices
are blocking the queries/responses (there may be more than one).
You may also want to talk to the manufactures first.  They should
be able to tell you how to configure your boxes to work correctly
to support DNSSEC.

As things are curently configured you won't get DNSSEC working.
You may need to upgrade firmware or even replace some boxes.  The
IP330 was introduced in 1999 so it may not have firmware that handles
DNSSEC properly.

Mark

> Thanks,
> 
> --=20
> Nicholas Wheeler
> Systems Administrator
> Development Infostructure
> 
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
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Re: Bind, dnssec, udp fragmentation woes.

2009-10-02 Thread Nicholas Wheeler
On Fri, 2009-10-02 at 13:22 +1000, Mark Andrews wrote:
> You really want to work out what is being blocked, EDNS?, responses
> bigger that 512 bytes? DNSSEC? fragmented responses?  With a clean
> path all of these should succeed but only the last one won't have
> "tc" set.  This does a plain DNS query, a EDNS query that limits
> the response to 512 bytes, a DNSSEC query that limits the response
> to 512 bytes, a DNSSEC query that limits the response to something
> that would not normally be fragmented but exceeds 512 bytes, a
> DNSSEC query that will normally be fragmented.
> 
> % dig soa se @192.36.133.107 +norec +ignore 
> % dig soa se @192.36.133.107 +norec +ignore +bufsize=512

The above two work, the below four do not work (connection timed out; no
servers could be reached). 

(note: I replaced se with my domain.tld, and the @ with my server).


> % dig dnskey se @192.36.133.107 +norec +ignore +bufsize=1200
> % dig dnskey se @192.36.133.107 +norec +ignore +bufsize=512 +dnssec
> % dig dnskey se @192.36.133.107 +norec +ignore +bufsize=1200 +dnssec
> % dig dnskey se @192.36.133.107 +norec +ignore +bufsize=4096 +dnssec
> 
> Mark

Thanks for the help, but I don't know what this implies, other than
nothing dnssec-related with udp works ;)

Thanks,

-- 
Nicholas Wheeler
Systems Administrator
Development Infostructure


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Re: Bind, dnssec, udp fragmentation woes.

2009-10-01 Thread Mark Andrews

You really want to work out what is being blocked, EDNS?, responses
bigger that 512 bytes? DNSSEC? fragmented responses?  With a clean
path all of these should succeed but only the last one won't have
"tc" set.  This does a plain DNS query, a EDNS query that limits
the response to 512 bytes, a DNSSEC query that limits the response
to 512 bytes, a DNSSEC query that limits the response to something
that would not normally be fragmented but exceeds 512 bytes, a
DNSSEC query that will normally be fragmented.

% dig soa se @192.36.133.107 +norec +ignore 
% dig soa se @192.36.133.107 +norec +ignore +bufsize=512
% dig dnskey se @192.36.133.107 +norec +ignore +bufsize=1200
% dig dnskey se @192.36.133.107 +norec +ignore +bufsize=512 +dnssec
% dig dnskey se @192.36.133.107 +norec +ignore +bufsize=1200 +dnssec
% dig dnskey se @192.36.133.107 +norec +ignore +bufsize=4096 +dnssec

Named does the following by default.  Ensure you have a up to date
version of namesd

dig dnskey se @192.36.133.107 +norec +ignore +bufsize=4096 +dnssec
dig dnskey se @192.36.133.107 +norec +ignore +bufsize=512 +dnssec
dig dnskey se @192.36.133.107 +norec +ignore

Mark
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org
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