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Unifi UDM + nextdns not resolving

Hi all,

I just installed the nextdns client on my UDM, which installed and configured successfully, listening on port 5342. But as far as I can tell only queries from the UDM itself are being resolved by nextdns. I don't see domains show up in the analytics or logs, coming from other devices on the network). Is there a configuration I am missing? Do I need to point the UnifiOS built-in DNS resolver (dnsmasq) to forward queries to the nextdns client? If so, how do I supply the custom port number?

Used these install instructions: https://github.com/nextdns/nextdns/wiki/UnifiOS

7 replies

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    • R_P_M
    • 1 yr ago
    • Reported - view
     said:
    Do I need to point the UnifiOS built-in DNS resolver (dnsmasq) to forward queries to the nextdns client? If so, how do I supply the custom port number?

     Yes you do need to forward seeing as it hasn’t auto configured completely.

     Just follow instructions here:

    https://github.com/nextdns/nextdns/wiki/DNSMasq-Integration

    and change the port number to what you have set already. 

      • Vlad_Vlasceanu
      • 1 yr ago
      • Reported - view

       Thanks for confirming my suspicion. That said, how does one:

      • Add the following settings to dnsmasq parameters: --server '127.0.0.1#5555' --add-mac --add-subnet=32,128

      ...on UnifiOS on a UDM Pro? I can't do it via the WebUI, because it doesn't let me supply a custom port. I'm assuming there would be a way via the CLI but my search skills are failing me... thoughts?

    • NextDNs
    • 1 yr ago
    • Reported - view

    The right settings should already be added to dnsmasq in this file: /run/dnsmasq.conf.d/nextdns.conf

    Can you share its content?

      • Vlad_Vlasceanu
      • 1 yr ago
      • Reported - view

       Here it is, you are right the settings are there. So what could be the issue then?

      # Configuration generated by NextDNS
no-resolv
server=127.0.0.1#5342
add-mac
add-subnet=32,128
max-cache-ttl=0

      Aa an example here's a DNS request from the UDM (SSH) to a domain I blocked for testing purposes:

      dig vladvlasceanu.com

; <<>> DiG 9.16.42-Debian <<>> vladvlasceanu.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63693
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
; EDE: 17 (Filtered): (Blocked by NextDNS)
;; QUESTION SECTION:
;vladvlasceanu.com. IN A

;; ANSWER SECTION:
vladvlasceanu.com. 5 IN CNAME blockpage.nextdns.io.
blockpage.nextdns.io. 5 IN A 45.32.79.76

;; Query time: 20 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri Oct 06 09:10:44 PDT 2023
;; MSG SIZE  rcvd: 120

      Here's the same request from a client Mac attached to the network (192.168.110.1 is the router IP in that VLAN):

      dig @192.168.110.1 vladvlasceanu.com

; <<>> DiG 9.10.6 <<>> @192.168.110.1 vladvlasceanu.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 40455
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;vladvlasceanu.com. IN A

;; Query time: 73 msec
;; SERVER: 192.168.110.1#53(192.168.110.1)
;; WHEN: Fri Oct 06 09:11:09 PDT 2023
;; MSG SIZE  rcvd: 46

      So it seems the queries are going to the upstream DNS servers of my internet provider (Spectrum):

      cat /etc/resolv.conf
# Generated automatically by ubios-udapi-server
nameserver 127.0.0.1
      cat /etc/resolv.dnsmasq
# Generated automatically by ubios-udapi-server
search socal.rr.com

# static nameservers
# eth8
nameserver 45.90.28.68
nameserver 45.90.30.68
      • NextDNs
      • 1 yr ago
      • Reported - view

       do you have the dnsfilter feature enabled on the UDM?

      • Vlad_Vlasceanu
      • 1 yr ago
      • Reported - view

       I think so, if this is what you mean by DNSfilter:

      1. Content Filtering set to "Work" for each VLAN
      2. Gateway Engine enabled in Application Firewall section

      Is that preventing DNS queries from flowing through nextdns?

      • Vlad_Vlasceanu
      • 1 yr ago
      • Reported - view

      Following up - the Content Filtering on the networks (VLANs) was the culprit. I turned it off and everything started working.

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Content aside

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