Adguard home DNS rewrites not functioning with DHCP server enabled

[anaander]

Prerequisites

• I have checked the Wiki and Discussions and found no answer

• I have searched other issues and found no duplicates

• I want to report a bug and not ask a question

Operating system type

Linux, Other (please mention the version in the description)

CPU architecture

AMD64

Installation

Docker

Setup

On one machine

AdGuard Home version

v0.107.11

Description

What did you do?

Created multiple DNS rewrites for hosts in the local IPs space in this format hostname.local.lan

Expected result

I can lookup the hosts

Actual result

I can only lookup the hosts with the DHCP server disabled

Screenshots (if applicable)

Additional information

lookup with DHCP disabled

.\doggo.exe cable.local.lan -n 10.0.0.206
NAME TYPE CLASS TTL ADDRESS NAMESERVER
cable.local.lan. A IN 10s 192.168.100.1 10.0.0.206:53

lookup with DHCP enabled

.\doggo.exe cable.local.lan -n 10.0.0.206
NAME TYPE CLASS TTL ADDRESS NAMESERVER STATUS
cable.local.lan. SOA IN 10s fake-for-negative-caching.adguard.com. 10.0.0.206:53 NXDOMAIN
hostmaster.cable.local.lan. 100500
1800 900 604800 86400

[anaander]

More about this; sort of "found a solution" but I'd still call it a bug.

Since my internal domain is "local.lan" I had to set the dhcp.local_domain_name to something else (in my case I just put in client.lan)

This allowed me use DNS rewrites for local.lan with DHCP enabled.

I also had to add

dhcp.dhcpv4.options:
- 15 hex 6C6F63616C2E6C616E

which pushed the actual domain name down to the clients when they lease an IP.

It also means the clients FQDN is registered with the incorrect domain when the IP is leased and a manual rewrite needs to be written for them to work properly.

[ainar-g]

Hello. Just to be clear, can you provide an example of the filtering rule you're applying? Or do you mean the Filters → DNS rewrites ones?

[anaander]

In AdGuardHome.yaml

user_rules:
  - '||pa-vm.local.lan^$dnsrewrite=NOERROR;A;10.0.0.248'
  - '||248.0.0.10.in-addr.arpa^$dnsrewrite=NOERROR;PTR;pa-vm.local.lan.'
dhcp:
  enabled: true
  interface_name: eth0
  local_domain_name: client.lan
  dhcpv4:
    gateway_ip: 10.0.0.254
    subnet_mask: 255.255.255.0
    range_start: 10.0.0.100
    range_end: 10.0.0.180
    lease_duration: 604800
    icmp_timeout_msec: 1000
    options:
      - 15 hex 6C6F63616C2E6C616E

Setting local_domain_name to 'local.lan' and enabling dhcp causes the custom filter to fail. Setting it to anything else (client.lan in this case) makes them to work.

[ainar-g]

I see, thanks! As a workaround, you could probably add a static lease with this IP and hostname. We'll see what we're able to do here.

[ainar-g]

@anaander, the most recent build on the Edge channel includes a fix for this. Could you please check if it works for you?

[anaander]

Switched my docker container over to adguard/adguardhome:edge image and changed the dhcp.local_domain_name to local.lan and the custom rules are now working with DHCP enabled.

Can confirm that the fix works. Thank you.