Local DNS discovery queries in AdGuard

Technical Support for Routers
1

I'm using DHCP from the Flint 2 GL Gui on 4.6.2 beta 1.

I'm using the AdGuard plugin as my local DNS server.

I have reverse private DNS queries enabled in AdGuard.

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Problem:

I see lookups for lb._dns-sd._udp.0.8.168.192.in-addr.arpa , db._dns-sd._udp.0.8.168.192.in-addr.arpa & b._dns-sd._udp.0.8.168.192.in-addr.arpa in AdGuard. Sometimes I also see these in the router system log where the DNS server running on the IPv6 Loopback address timed out.

Shouldn't dnsmasq be answering these requests? What result should be returned? Right now these requests are returning NXDOMAIN in AdGuard because of course my upstream servers don't have an answer.

I can still do PTR lookups of local devices successfully using nslookup like nslookup -type=ptr 192.168.8.141 so what gives?

2

Anyone else have this problem?

How should I solve it?

3

The ADG already handle all DNS query in the router (port 53 -> 3053), all reply is from the ADG, dnsmasq service would not process DNS.
May try to check the DNS setting in the ADG. For others, no idea.

4

The problem is that these local queries are by default sent back to the local dns server on the router

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But dnsmasq doesn't know how to respond so these requests timeout.

Tue Aug 20 10:22:14 2024 user.notice AdGuardHome[14118]: 2024/08/20 09:22:14.389343 [error] dnsproxy: [::1]:53: response received over udp: "exchanging with [::1]:53 over udp: read udp [::1]:51997->[::1]:53: i/o timeout"
Tue Aug 20 10:22:14 2024 user.notice AdGuardHome[14118]: 2024/08/20 09:22:14.389454 [error] dnsproxy: upstream [::1]:53 failed to exchange ;db._dns-sd._udp.0.1.168.192.in-addr.arpa.	IN	 PTR in 2.001780858s: exchanging with [::1]:53 over udp: read udp [::1]:51997->[::1]:53: i/o timeout
Tue Aug 20 10:22:14 2024 user.notice AdGuardHome[14118]: 2024/08/20 09:22:14.389344 [error] dnsproxy: [::1]:53: response received over udp: "exchanging with [::1]:53 over udp: read udp [::1]:39166->[::1]:53: i/o timeout"
Tue Aug 20 10:22:14 2024 user.notice AdGuardHome[14118]: 2024/08/20 09:22:14.389519 [error] dnsproxy: upstream [::1]:53 failed to exchange ;lb._dns-sd._udp.0.1.168.192.in-addr.arpa.	IN	 PTR in 2.001094585s: exchanging with [::1]:53 over udp: read udp [::1]:39166->[::1]:53: i/o timeout
Tue Aug 20 10:22:14 2024 user.notice AdGuardHome[14118]: 2024/08/20 09:22:14.389343 [error] dnsproxy: [::1]:53: response received over udp: "exchanging with [::1]:53 over udp: read udp [::1]:33294->[::1]:53: i/o timeout"
Tue Aug 20 10:22:14 2024 user.notice AdGuardHome[14118]: 2024/08/20 09:22:14.390245 [error] dnsproxy: upstream [::1]:53 failed to exchange ;b._dns-sd._udp.0.1.168.192.in-addr.arpa.	IN	 PTR in 2.002680514s: exchanging with [::1]:53 over udp: read udp [::1]:33294->[::1]:53: i/o timeout

It's not a circular loop because I've turned off forwarding for Private queries

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Queries like dig -z 192.168.1.x return the correct hostname.

But the dns-sd queries just return nxdomain and timeout.

6

Is there a problem with not turning on adguardhome?

7

Yes I would like to use adguardhome

8

We cannot reproduce this situation, please let us know the further info about that how to configure and reproduce. As well please draw a topology.

9

What is your firewall with port forward in luci?

10

have you tested with Apple devices? because it's Apple devices that make these requests.

My issue with these requests is they mess up the adguard stats but they don't break any actual function on the Mac

11

just 80, 443, and 2 other port forwards which aren't dns related

12

Something wrong, should be adguard dns port and Adguard dns guest port

1 Like
13

hmm, I only have these 2 rules in addition to the ones you mentioned.

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But since I'm not using Override DNS Settings of All Clients this is expected imo

14

Result adguard home won't listen any ports 53 >3053 what @bruce said.

1 Like
15

Likely only reproducible with AdGuard version > 0.107.46 e.g. latest

16

Hi, the router I tested is in the v0.107.46, it seems there is no problem.
May I know what version of the ADG you test?

18

v0.107.46 with 4.6.2

I don't think this is a problem though.

It's the weekend so not been using my work laptop and I don't see the queries in the logs so far today.

I think since I have the setting enabled in luci these requests are forwarded to the correct DNS resolver but i don't know what the actual answer for these requests should be.

I can't find that on the internet

19

Probably some configurations/plugins installed of the Luci to cause this issue.
Please try to reset the router if you are convenient to check the ADG again, since I did not know what the configurations you have modified.

20

i will reset the router when i have some time to upgrade to 4.6.4

This behaviour happens out of the box but i will send you my config when I reset the router and the problem still occurs without any plugins or configuration

21

I also have these show up for a friend of mine on his Flint 2.

What causes these ? The router's log is filled with them. I don't see them on my Flint 2 though.

Sun Oct 20 10:42:47 2024 user.notice AdGuardHome[8307]: 2024/10/20 10:42:47.038638 [error] dnsproxy: [::1]:53: response received over udp: "exchanging with [::1]:53 over udp: read udp [::1]:54495->[::1]:53: i/o timeout"
Sun Oct 20 10:42:47 2024 user.notice AdGuardHome[8307]: 2024/10/20 10:42:47.038738 [error] dnsproxy: upstream [::1]:53 failed to exchange ;lb._dns-sd._udp.0.8.168.192.in-addr.arpa.	IN	 PTR in 2.00122985s: exchanging with [::1]:53 over udp: read udp [::1]:54495->[::1]:53: i/o timeout
Sun Oct 20 10:42:47 2024 user.notice AdGuardHome[8307]: 2024/10/20 10:42:47.039730 [error] dnsproxy: 127.0.0.1:53: response received over udp: "exchanging with 127.0.0.1:53 over udp: read udp 127.0.0.1:45225->127.0.0.1:53: i/o timeout"
Sun Oct 20 10:42:47 2024 user.notice AdGuardHome[8307]: 2024/10/20 10:42:47.039825 [error] dnsproxy: upstream 127.0.0.1:53 failed to exchange ;lb._dns-sd._udp.0.8.168.192.in-addr.arpa.	IN	 PTR in 2.000956328s: exchanging with 127.0.0.1:53 over udp: read udp 127.0.0.1:45225->127.0.0.1:53: i/o timeout
22

Cheek your firewall port forward in luci