How to selectively skip DNSSEC validation?

[Mark Andrews]

> On 8 Dec 2020, at 09:02, Andrew P. <andrewemt at hotmail.com> wrote:
> 
> Greetings, all.
> 
> I'm having an odd problem, and I can't seem to figure out how to get Bind to behave the way I need it to.
> 
> I have a computer with a caching-only Bind instance (version 9.11.24-RedHat-9.11.24-2.fc32), which is used both to access the regular Internet and to access the Amateur Radio Emergency Data Network (AREDN). AREDN is an RF intranet, and it has its own instance of name servers, which do not use encryption (as this is prohibited by national and international amateur radio laws and regulations). As such, I tried to add forwarding entries for the top-level domains in AREDN to my /etc/named.conf file as follows:

DNSSEC is not encryption, it is authentication. Both can use public key cryptography.  DOT (DNS over TLS) and DOH (DNS over HTTPS) are encrypted forms of DNS.

Similarly TSIG is authentication not encryption.

TKEY uses encryption to transmit keys for TSIG between server and client.

> zone "mesh." IN {
>        type forward;
>        delegation-only no;
>        forward only;
>        forwarders { 192.168.0.7; };
> };

Yet another group that thinks that using TLD names without permission is a good idea rather than co-ordinating the use with ICANN. You wouldn’t have to ask here if the use was co-ordinated.  You also wouldn’t have to do hacks like adding a forward zone for .MESH.  You also won’t have to deal with consequences of when ICANN delegate .MESH to someone else which is well within their purview to do.

> zone "local.mesh." IN {
>        type forward;
>        delegation-only no;
>        forward only;
>        forwarders { 192.168.0.7; };
> };
> 
> zone "10.in-addr.arpa." IN {
>        type forward;
>        forward only;
>        forwarders { 192.168.0.7; };
> };
> 
> The options section of the file specifies
> 
>        recursion yes;
>        dnssec-enable yes;
>        dnssec-validation yes;
> 
> Note that 192.168.0.7 is my local LAN address for my AREDN node (which includes DNS service on standard port 53).
> 
> However, whenever I try to do a lookup of an AREDN mesh domain name, it properly forwards to the AREDN node for service, and then complains to syslog:
> 
> Dec  7 14:54:39 server named[207007]: no valid RRSIG resolving 'aa3e-southwest-230.local.mesh/DS/IN': 192.168.0.7#53
> Dec  7 14:54:39 server named[207007]: no valid DS resolving 'aa3e-southwest-230.local.mesh/A/IN': 192.168.0.7#53
> 
> and returns a SERVFAIL error to the client.
> 
> If I use nslookup directly to the AREDN node, the lookup succeeds. But this won't work for a system that needs arbitrary applications (such as web browsers) to look up both Internet and AREDN names.
> 
> I have confirmed that neither the global Internet servers nor the AREDN intranet servers have RRSIG or DS records for the mesh or local.mesh domains. And lookups of Internet domain names (or even my non-secured local private subnet zones) still works successfully.
> 
> So, how can I configure Bind to skip the DNSSEC checks _only_ when going to the specific AREDN server, or, alternatively, only for the zones mentioned above? Either method would be acceptable; ideal would be to restrict it to the intersection of both server and zones. Given the number of criminals and identity thieves on the Internet, I can't just turn off DNSSEC checks globally. And I can't use separate computers with separate Bind instances because I need to be able to selectively relay traffic between the Internet and AREDN.

Upgrade to BIND 9.16 and use validate-except.

> The use of "delegation-only no;" in the above zone definitions was an attempt to work around the problem, but it didn't change the behavior over not having the option there. The version of Bind I am using does not permit putting the "dnssec-enable" and "dnssec-validation" options inside a zone definition.
> 
> I look forward to your advice in this matter.
> 
> Andrew Pavlin, KA2DDO
> member, Amateur Radio Emergency Service
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka at isc.org