[Feature request] How to setup reverse DNS and add an A record

[ghost]

Prerequisites

• I am running the latest version
• I checked the documentation and found no answer
• I checked to make sure that this issue has not already been filed

Problem Description

How to setup reverse DNS and add an A record

[ameshkov]

Could you please be more specific?

Reverse DNS and A records are a little bit different things

[ghost]

sorry,it's two functions

1. setup reverse DNS
2. add an A record

[ghost]

eg

Configuring Reverse DNS in BIND 9

add A record in bind9

[ameshkov]

setup reverse DNS

Not possible in the current version, but that's a good case for #2102.

@ainar-g would it be possible with $dnsrewrite in it's current implementation?

add an A record

You can use "Filters -> DNS rewrites" settings for that.

[jeffr1975]

DNS rewrites cause major problems with nginx reverse proxy with subdomains. A records on pihole work fine. I can't find a nginx config that allows it to handle dns rewrites. Just having support for A records would be very good.

[ameshkov]

I honestly have no idea how DNS rewrites and nginx are connected.

Basically, when you add a DNS rewrite that looks like example.org -> 127.0.0.1, you are adding an A record.

If you want a more fine-grained control over it, you can use $dnsrewrite rules:
https://github.com/AdguardTeam/AdGuardHome/wiki/Hosts-Blocklists#dnsrewrite

[ainar-g]

@ameshkov, you mean, the Reverse DNS part? Not currently, but overall the extension seems to be trivial. Maybe for v0.106.0? We have enough on our plate for v0.105.0 currently.

[ameshkov]

@ainar-g why can't I add 192.168.0.1.in-addr.arpa$dnsrewrite=NOERROR:PTR:hostname?

[ainar-g]

@ameshkov, because different record types have different types of values, and we decode them into RRValues correspondingly. And we also need to catch the CNAME exception at the same stage.

https://github.com/AdguardTeam/urlfilter/blob/d0665c13ffaaba988fd29def346ac032c7eeb4bd/rules/dnsrewrite.go#L129-L168

We could just put the value as verbatim text in the default case, but that means that when we do decode the value properly in the future, we may break some clients.

[ameshkov]

@ainar-g it should be explained in the documentation that some RRTypes don't support values yet.

There're some that are rather important and would be useful to have in the first release:

• HTTPS - this record type may be really useful. For instance, people may use it to achieve "HTTPS everywhere"-like behavior.
• PTR - for configuring hostnames on the network. May also be useful to setup bonjour-like services.
• MX - for configuring mail servers on the network.

Please check how complicated is it to add those.

[ainar-g]

@ameshkov, PTR looks easy enough. Do we need an ability to set MX's PREFERENCE parameter? If no, also easy; if yes, medium-easy, once we agree on a format.

As far as I can see, HTTPS is basically the same as SVCB, so we could technically get both in one go. Again, we need to agree on the syntax first. After that, the difficulty seems to be medium.

[ameshkov]

Here's how I suggest to deal with MX:

|google.com^$dnsrewrite=NOERROR:MX:30 alt2.aspmx.l.google.com.

;; ANSWER SECTION:
google.com.		187	IN	MX	30 alt2.aspmx.l.google.com.

No complicated stuff is needed.

[ainar-g]

Should be possible as of v0.105.0-beta.2. @da-gongren, can you please update and check?

Wiki docs.