Dnssec-validation auto

Petr Menšík pemensik at redhat.com
Fri Nov 13 13:19:47 UTC 2020


I would check what nameservers are in /etc/resolv.conf, and try to
direct delv or dig to its address.

for H in $(awk '$1 == "nameserver" { print $2 }' /etc/resolv.conf); do
dig +dnssec @$H www.popularsba.com; done

Check every server returns reliable and the same results. I had one
NOERROR and one SERVFAIL from our instrastructure. The second server
provides more servers in ADDITIONAL section. Second retry was successful.

It might take a bit more time to fetch and verify addresses of all
authoritative servers of gslb.siteforce.com. domain. Six seems a lot.


; <<>> DiG 9.11.20-RedHat-9.11.20-5.el8 <<>> +dnssec @10.5.30.45
www.popularsba.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43145
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 6, ADDITIONAL: 13

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
;; QUESTION SECTION:
;www.popularsba.com.		IN	A

;; ANSWER SECTION:
www.popularsba.com.	262	IN	CNAME
www.popularsba.com.00d1n000002kxqqua0.live.siteforce.com.
www.popularsba.com.00d1n000002kxqqua0.live.siteforce.com. 262 IN CNAME
4.0p13m0000008e6qcaq.00d1n000002kxqqua0.gslb.siteforce.com.
4.0p13m0000008e6qcaq.00d1n000002kxqqua0.gslb.siteforce.com. 82 IN A
13.109.220.200

;; AUTHORITY SECTION:
gslb.siteforce.com.	55886	IN	NS	dns05.salesforce.com.
gslb.siteforce.com.	55886	IN	NS	dns01.salesforce.com.
gslb.siteforce.com.	55886	IN	NS	dns02.salesforce.com.
gslb.siteforce.com.	55886	IN	NS	dns04.salesforce.com.
gslb.siteforce.com.	55886	IN	NS	dns06.salesforce.com.
gslb.siteforce.com.	55886	IN	NS	dns03.salesforce.com.

;; ADDITIONAL SECTION:
dns01.salesforce.com.	53547	IN	A	204.74.108.235
dns02.salesforce.com.	53547	IN	A	204.74.109.235
dns04.salesforce.com.	53547	IN	A	199.7.69.235
dns03.salesforce.com.	53547	IN	A	199.7.68.235
dns06.salesforce.com.	53547	IN	A	204.74.115.235
dns05.salesforce.com.	53547	IN	A	204.74.114.235
dns01.salesforce.com.	53547	IN	RRSIG	A 13 3 86400 20201130021251
20201001013506 2317 salesforce.com.
fUb+1uVGcdeVSsjTj1O++bcNLZwapzTvLcHLP+tykm3y3ziCSIHtxfCp
3kZqdBQtB3nGd7ySGPEblvBJA4ZHUA==
dns02.salesforce.com.	53547	IN	RRSIG	A 13 3 86400 20201130021251
20201001013506 2317 salesforce.com.
QOVhwrJ0dwkHRHLr/ytEzmZ04bYaAzN2ooDfJOVJXDCinYGFuNTRmPhs
uFawDGlRlFja8OyiIyJXIFvwXKGSxg==
dns04.salesforce.com.	53547	IN	RRSIG	A 13 3 86400 20201130021251
20201001013506 2317 salesforce.com.
DXOOYz5odrnY7SkWNvU0NiGOZEWalNT+0VYCYgd7wl6Rj0cOR4slFrvR
ADj5eAgFLybADvTviia/xbqz4u7ueQ==
dns03.salesforce.com.	53547	IN	RRSIG	A 13 3 86400 20201130021251
20201001013506 2317 salesforce.com.
Rkzv/z9vhnURB8hueZgkQrKFffLB9Zj423ZPHoPXtoECxNVk/ZV/ODv4
BQZLT8+t8W7cLILNyXVVpEjG2ejE9Q==
dns06.salesforce.com.	53547	IN	RRSIG	A 13 3 86400 20201218220609
20201019213201 2317 salesforce.com.
YcTDijezumyiv+WZcvZqFk/yOJ2r7WdxZ5XFwIjt5R6iDOSQNChxhQ3G
dhR28sLna+rM9yVehyyEyCh4iJUeHg==
dns05.salesforce.com.	53547	IN	RRSIG	A 13 3 86400 20201130021251
20201001013506 2317 salesforce.com.
gmzIaK0lTolbkUaIGfHTLl2+TzUYQUtxHJ5yevEzdLmaE8z0AW7JBVXf
07osroe/7LxRQO38ZCxNZHVXfQnMHA==

;; Query time: 45 msec
;; SERVER: 10.5.30.45#53(10.5.30.45)
;; WHEN: Fri Nov 13 08:12:49 EST 2020
;; MSG SIZE  rcvd: 1076


It seems to me, only dns0?.salesforce.com. hosts are in DNSSEC signed
domain. Try debuging salesforce.com. domain verification instead.

On 11/13/20 1:59 PM, Ismael Suarez wrote:
> With "dnssec-validation AUTO;" I get:
> 
> # delv +cd www.popularsba.com
> ;; resolution failed: timed out
> 
> 
> With "dnssec-validation NO;" I get:
> 
> # delv +cd www.popularsba.com
> ;; resolution failed: timed out
> ; unsigned answer
> www.popularsba.com.     279     IN      CNAME   www.popularsba.com.00d1n000002kxqqua0.live.siteforce.com.
> 
> 
> CAPS just to show the difference in .conf
> 
> 
> --
> 
> Ismael Suárez Maldonado | UNIX ADM | Coqui.Net Corp / ClaroTV
> ismael_suarez at coqui.com<mailto:ismael_suarez at coqui.com> | T: 787-793-0001 x 4007
> 
> -----Original Message-----
> From: Petr Menšík <pemensik at redhat.com<mailto:Petr%20%3d%3fUTF-8%3fQ%3fMen%3dC5%3dA1%3dC3%3dADk%3f%3d%20%3cpemensik at redhat.com%3e>>
> To: bind-users at lists.isc.org<mailto:bind-users at lists.isc.org>
> Subject: Re: Dnssec-validation auto
> Date: Fri, 13 Nov 2020 11:26:17 +0100
> 
> 
> Hi Ismael,
> 
> 
> easiest way to check validation is using delv tool from BIND 9.11+. It
> 
> uses the same algorithm as BIND server does. If you get SERVFAIL from
> 
> your recursive server, try adding +cd parameter to delv or dig. When it
> 
> works with +cd, validation is responsible somewhere in recursive servers
> 
> chain.
> 
> 
> It shows just unsigned to me, today.
> 
> 
> $ delv +cd
> 
> <http://www.popularsba.com>
> 
> www.popularsba.com
> 
> 
> ; unsigned answer
> 
> <http://www.popularsba.com>
> 
> www.popularsba.com
> 
> .       282     IN      CNAME
> 
> <http://www.popularsba.com.00d1n000002kxqqua0.live.siteforce.com>
> 
> www.popularsba.com.00d1n000002kxqqua0.live.siteforce.com
> 
> .
> 
> <http://www.popularsba.com.00d1n000002kxqqua0.live.siteforce.com>
> 
> www.popularsba.com.00d1n000002kxqqua0.live.siteforce.com
> 
> . 282 IN CNAME
> 
> 4.0p13m0000008e6qcaq.00d1n000002kxqqua0.gslb.siteforce.com.
> 
> 4.0p13m0000008e6qcaq.00d1n000002kxqqua0.gslb.siteforce.com. 102 IN A
> 
> 161.71.31.253
> 
> 
> Cheers,
> 
> Petr
> 
> 
> On 11/13/20 5:26 AM, Ismael Suarez wrote:
> 
> Hi all
> 
> 
> The following domain (
> 
> <http://www.popularsba.com>
> 
> www.popularsba.com
> 
> ) does not resolve with dnssec validation set to auto, but when I change the validation off it works.
> 
> 
> Why is this? How can I check this validation?
> 
> 
> Using bind 9.12
> 
> 
> Thanks to all
> 
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-- 
Petr Menšík
Software Engineer
Red Hat, http://www.redhat.com/
email: pemensik at redhat.com
PGP: DFCF908DB7C87E8E529925BC4931CA5B6C9FC5CB
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