CNAME restrictions

[Leroy Tennison]

I have a situation where, due to the system's location (IP subnet), its DNS name is <webserver>.<internal subdomain>.datavoiceint.com. We have a certificate for *.datavoiceint.com which we prefer to use instead of having to acquire a certificate for <internal subdomain>.datavoiceint.com since this is a one-off internal-only web server. Our (ISC) DNS servers (version 9.10.3-P4-Ubuntu that comes with Ubuntu 16.04) serve both domains. I thought a solution would be to use a CNAME but, when I attempt this (via nsupdate with the update key which works for A and PTR adds and deletes) I get (on "send"):

TSIG error with server: expected a TSIG or SIG(0)
update failed: NOTIMP

What I tried (on both <internal subdomain>.datavoiceint.com. and datavoiceint.com.) was:

update add <webserver>.datavoiceint.com. 86400 IN CNAME <webserver>.<internal subdomain>.datavoiceint.com.

Apparently I'm mis-understanding CNAME usage, if I actually can use a CNAME record what should the format be (or do I need to configure bind differently to use it since part of the reply is NOTIMP)? If that's not possible due to CNAME restrictions are there any alternatives?

Thanks for your help.

Harriscomputer

Leroy Tennison
Network Information/Cyber Security Specialist
E: ***@datavoiceint.com
P:


[cid:Data-Voice-International-LOGO_aa3d1c6e-5cfb-451f-ba2c-af8059e69609.PNG]


2220 Bush Dr
McKinney, Texas
75070
www.datavoiceint.com<http://www..com>


This message has been sent on behalf of a company that is part of the Harris Operating Group of Constellation Software Inc.

If you prefer not to be contacted by Harris Operating Group please notify us<http://subscribe.harriscomputer.com/>.



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[Matus UHLAR - fantomas]

On 04.08.20 17:29, Leroy Tennison wrote:
>I have a situation where, due to the system's location (IP subnet), its DNS
> name is <webserver>.<internal subdomain>.datavoiceint.com. We have a
> certificate for *.datavoiceint.com which we prefer to use

wildcard in certificates only covers one level of subdomains, so
*.datavoiceint.com will cover <internal subdomain>.datavoiceint.com but not
anything under it.

you will have to strip the <webserver> part or get other certificate.

--
Matus UHLAR - fantomas, ***@fantomas.sk ; http://www.fantomas.sk/
Warning: I wish NOT to receive e-mail advertising to this address.
Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
Microsoft dick is soft to do no harm

[Kevin Darcy]

[ Classification Level: GENERAL BUSINESS ]

Offhand, it looks like the server side is configured to only allow
authenticated updates, but you're sending an unauthenticated one.

A more nuanced issue might be if the ID you're running the nsupdate as,
can't read the key files, so even though you may have intended the update
to be signed, it actually wasn't.

Did you try adding a -d to the nsupdate command? If so, does the debug
output give any clues?

-
Kevin

On Tue, Aug 4, 2020 at 1:30 PM Leroy Tennison <***@datavoiceint.com>
wrote:

> I have a situation where, due to the system's location (IP subnet), its
> DNS name is <webserver>.<internal subdomain>.datavoiceint.com. We have a
> certificate for *.datavoiceint.com which we prefer to use instead of
> having to acquire a certificate for <internal subdomain>.datavoiceint.com
> since this is a one-off internal-only web server. Our (ISC) DNS servers
> (version 9.10.3-P4-Ubuntu that comes with Ubuntu 16.04) serve both
> domains. I thought a solution would be to use a CNAME but, when I attempt
> this (via nsupdate with the update key which works for A and PTR adds and
> deletes) I get (on "send"):
>
> TSIG error with server: expected a TSIG or SIG(0)
> update failed: NOTIMP
>
> What I tried (on both <internal subdomain>.datavoiceint.com. and
> datavoiceint.com.) was:
>
> update add <webserver>.datavoiceint.com. 86400 IN CNAME <webserver>.<internal
> subdomain>.datavoiceint.com.
>
> Apparently I'm mis-understanding CNAME usage, if I actually can use a
> CNAME record what should the format be (or do I need to configure bind
> differently to use it since part of the reply is NOTIMP)? If that's not
> possible due to CNAME restrictions are there any alternatives?
>
> Thanks for your help.
>
> Harriscomputer
>
>
> *Leroy Tennison*Network Information/Cyber Security Specialist
> E: ***@datavoiceint.com
> P:
>
>
> 2220 Bush Dr
> McKinney, Texas
> 75070
> www.datavoiceint.com <http://www..com>
>
> This message has been sent on behalf of a company that is part of the
> Harris Operating Group of Constellation Software Inc.
>
> If you prefer not to be contacted by Harris Operating Group please notify
> us <http://subscribe.harriscomputer.com/>.
>
>
>
> This message is intended exclusively for the individual or entity to which
> it is addressed. This communication may contain information that is
> proprietary, privileged or confidential or otherwise legally exempt from
> disclosure. If you are not the named addressee, you are not authorized to
> read, print, retain, copy or disseminate this message or any part of it. If
> you have received this message in error, please notify the sender
> immediately by e-mail and delete all copies of the message.
>
>
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[Leroy Tennison]

Thank you, -d surfaced the issue - now to decide what to do about it...

________________________________
From: bind-users <bind-users-***@lists.isc.org> on behalf of Kevin Darcy <***@fcagroup.com>
Sent: Tuesday, August 4, 2020 3:28 PM
To: bind-***@lists.isc.org <bind-***@lists.isc.org>
Subject: [EXTERNAL] Re: CNAME restrictions


CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.


[ Classification Level: GENERAL BUSINESS ]

Offhand, it looks like the server side is configured to only allow authenticated updates, but you're sending an unauthenticated one.

A more nuanced issue might be if the ID you're running the nsupdate as, can't read the key files, so even though you may have intended the update to be signed, it actually wasn't.

Did you try adding a -d to the nsupdate command? If so, does the debug output give any clues?

- Kevin

On Tue, Aug 4, 2020 at 1:30 PM Leroy Tennison <***@datavoiceint.com<mailto:***@datavoiceint.com>> wrote:
I have a situation where, due to the system's location (IP subnet), its DNS name is <webserver>.<internal subdomain>.datavoiceint.com<https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fdatavoiceint.com&c=E,1,0gSBGzOV_9iJ4F-vOfqNwsk4Kjf6AQvm_Nt3gjCZAng77d3CYgiVYS_-yNeGK3M-LLCuD8B-erwPcTNMkAxJaTdxayw90W-cIVfFe6TBpYonsjiZafcGPSBGsgSS&typo=1>. We have a certificate for *.datavoiceint.com<https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fdatavoiceint.com&c=E,1,e3FlEDT18o4d4tQSRMvBH_pJRuK7156_n6wtGIzdpwjQt88Y_j375seki-O4IjtqsVLmsYGablGT9qnLV7jap1khSDSeV8Qt3U6JQ73WAhGbMMeoi10k&typo=1> which we prefer to use instead of having to acquire a certificate for <internal subdomain>.datavoiceint.com<https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fdatavoiceint.com&c=E,1,6-PPelQOIFl5wSdbP2RNe2N6pkrhqneq6Ezfx3p5-pXYgNrt6J521WJEJJKFmvxtsjfuSzRbWHJnSbpTUyu6XqeAeCg6OO0-KzDJiXfe1ccW7qg9pN7g2CgI&typo=1> since this is a one-off internal-only web server. Our (ISC) DNS servers (version 9.10.3-P4-Ubuntu that comes with Ubuntu 16.04) serve both domains. I thought a solution would be to use a CNAME but, when I attempt this (via nsupdate with the update key which works for A and PTR adds and deletes) I get (on "send"):

TSIG error with server: expected a TSIG or SIG(0)
update failed: NOTIMP

What I tried (on both <internal subdomain>.datavoiceint.com<https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fdatavoiceint.com&c=E,1,WqKTpCcatx2SaWvqy4SyBLF0mNa1-gW8LKH80Ec2eWBinE3E7c5lEHLpjRuSiRnF_xc32FO_Ke1HOfMD3_RKS1c_-Gb4quMBWrNQrHh74wi-HJkg&typo=1>. and datavoiceint.com<https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fdatavoiceint.com&c=E,1,gDRbc9b7Hocp2adLEqMg2H4aBk9B80nSlj9DRUkwds45t2gqX4OYSPpS7T0rTc7SpPNhIUwv5Qxh01PYiNrEy5_9cB7--c16EqfcCxXOM4w,&typo=1>.) was:

update add <webserver>.datavoiceint.com<https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fdatavoiceint.com&c=E,1,LMSRr0xOj2dbcOJlyj5U8VIFyRH5ecttdkU4Je538OMUPmbLfqBLc5uT1bH4P4-AQWj7eME7APcmrfzjgPYOORSQ1gGlo41FqXQQU67iTV6fGo1tYi-G3-c,&typo=1>. 86400 IN CNAME <webserver>.<internal subdomain>.datavoiceint.com<https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fdatavoiceint.com&c=E,1,K69ghu-8VkYZl4XrnMCfdzlp4UUfK2BGmh9Q9xWS3VzeXkVGOtpJequZa-J_gQCYM2J904MVlyeH5VboQjCatM-y6QbI5FtcIV32w9Cx&typo=1>.

Apparently I'm mis-understanding CNAME usage, if I actually can use a CNAME record what should the format be (or do I need to configure bind differently to use it since part of the reply is NOTIMP)? If that's not possible due to CNAME restrictions are there any alternatives?

Thanks for your help.

Harriscomputer

Leroy Tennison
Network Information/Cyber Security Specialist
E: ***@datavoiceint.com<mailto:***@datavoiceint.com>
P:


[cid:Data-Voice-International-LOGO_aa3d1c6e-5cfb-451f-ba2c-af8059e69609.PNG]


2220 Bush Dr
McKinney, Texas
75070
www.datavoiceint.com<http://www..com>


This message has been sent on behalf of a company that is part of the Harris Operating Group of Constellation Software Inc.

If you prefer not to be contacted by Harris Operating Group please notify us<https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fsubscribe.harriscomputer.com%2f&c=E,1,tDHN8eusdo1dmAH7sVm4QCbMt63IMR6Im_-2r3epFrKvWDlRIiNUdnjRrqlc7YbDFZi26vf4PH2bi8fXxWwxgooQFPSr0rZ89dfsdV3EvGhNQhzOxc6dkeUO&typo=1>.



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Harriscomputer

Leroy Tennison
Network Information/Cyber Security Specialist
E: ***@datavoiceint.com
P:


[cid:Data-Voice-International-LOGO_aa3d1c6e-5cfb-451f-ba2c-af8059e69609.PNG]


2220 Bush Dr
McKinney, Texas
75070
www.datavoiceint.com<http://www..com>


This message has been sent on behalf of a company that is part of the Harris Operating Group of Constellation Software Inc.

If you prefer not to be contacted by Harris Operating Group please notify us<http://subscribe.harriscomputer.com/>.



This message is intended exclusively for the individual or entity to which it is addressed. This communication may contain information that is proprietary, privileged or confidential or otherwise legally exempt from disclosure. If you are not the named addressee, you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If you have received this message in error, please notify the sender immediately by e-mail and delete all copies of the message.