CNAME restrictions

Tue Aug 4 22:25:45 UTC 2020

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

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

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[ 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 <leroy at datavoiceint.com<mailto:leroy at 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: leroy at datavoiceint.com<mailto:leroy at datavoiceint.com>
P:

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www.datavoiceint.com<http://www..com>

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Harriscomputer

Leroy Tennison
Network Information/Cyber Security Specialist
E: leroy at 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.

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