topic Re: DNS-base application in Next-Generation Firewall Discussions

DNS-base application

Qui — Fri, 08 Jul 2022 00:36:57 GMT

Hi ALL,

In our monitor log ,we see a lot of deny for a few PCs with "dns-base" application .

Please see below:

what is "DNS-base" and how do we allow it if needed.

Thanks

Re: DNS-base application

Adrian_Jensen — Fri, 08 Jul 2022 21:31:53 GMT

"dns-base" is one of the subsets of the "dns" application ID. The "dns" application ID is currently being split into to separate subcategories so those who want can filter non-compliant DNS requests:

dns-base: general DNS requests

dns-non-rfc: Non-RFC complaint DNS requests

You can see the descriptions of these application IDs on your PaloAlto under:

Objects -> Applications -> search "dns" and then click the dns application names

dns-non-rfc was introduced June 21 2022 and is scheduled for activation July 19 2022. You can read more here:

https://live.paloaltonetworks.com/t5/customer-resources/dns-app-id-enhancement-release-plan/ta-p/487590

If your current Security Policies allow application ID "dns", that will include both subsets. If you only want to allow RFC compliant DNS traffic, then your Security Policy should only allow "dns-base" (non-RFC compliant will be excluded after July 19).

Since your current Security Policy set is denying DNS traffic, I would start looking at your current rule to allow "dns" or "dns-base". Is it applied to the correct zones, source/destination addresses, and using "application default" or "any" Service?

IMPORTANT EDIT: Re-reading the enhancement release now, there are recent comments that people using "dns" application ID had their Security Policy broken, they had to explicitly add the subset "dns-base" to get DNS working again. See this follow up article with release information:

https://live.paloaltonetworks.com/t5/customer-resources/customer-issue-impacting-applications-and-threats-content-update/ta-p/506844

Re: DNS-base application

Qui — Mon, 11 Jul 2022 00:31:10 GMT

We allow "DNS" and port TCP 53 & UPD 53 in the security rule but user still complain not working.

we change the rule for "any" service and it is working for them now.

Thank you for the insight knowledge.

Much appreciated

Re: DNS-base application

kdonohue — Wed, 20 Jul 2022 15:11:27 GMT

I have come across the same issue. Even if you have the "DNS" application allowed, even though the dns-base is listed as a subset, it will get dropped. I had to allow both "DNS" & "DNS-BASE" and my domain authentication and lookups started to work properly again.