DNS listening address changes from 127.0.0.1 to 0.0.0.0 after startup

[laggardkernel]

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Prerequisites

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• 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

Issue Details

• Version of AdGuard Home server:
  • version v0.105.2, channel release, arch darwin amd64
• How did you install AdGuard Home:
  • Github releases
• How did you setup DNS configuration:
  • System
• If it's a router or IoT, please write device model:
  • Macbook
• CPU architecture:
  • x86_64
• Operating system and version:
  • macOS 10.14.6

Description

DNS is set to bind on 127.0.0.1 in configuration, but it changes to 0.0.0.0 on specific condition. Seems only UDP listening address is affected.

Related conf

dns:
  bind_host: 127.0.0.1
  port: 53

How to reproduce the bug.

❯ AdGuardHome --version
AdGuard Home, version v0.105.2, channel release, arch darwin amd64

# Clear the DNS set in "System Preferences -> Network",
# change it back to the DNS dispatch by the router
❯ networksetup -setdnsservers "Wi-Fi" empty

# Check the conf file to make sure `bind_host` is set `127.0.0.1`.
# Then start adguard home
❯ sudo AdGuardHome -w /usr/local/etc/adguardhome -s start
2021/03/12 13:19:33 [info] Service control action: start
2021/03/12 13:19:33 [info] Action start has been done successfully on darwin-launchd

~
❯ sudo lsof -i :53
COMMAND     PID USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
AdGuardHo 77951 root   15u  IPv4 0x75e1237716cbfaa9      0t0  UDP localhost:domain
AdGuardHo 77951 root   22u  IPv4 0x75e1237726b74fc9      0t0  TCP localhost:domain (LISTEN)

# Set 127.0.0.1 as the default DNS on the OS. No different with setting it in "system preferences -> network"
❯ networksetup -setdnsservers "Wi-Fi" 127.0.0.1

# Here's the problem. Listening address is changed dynamically.
❯ sudo lsof -i :53
COMMAND     PID USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
AdGuardHo 77951 root   15u  IPv4 0x75e1237716cbfaa9      0t0  UDP *:domain  # weird
AdGuardHo 77951 root   22u  IPv4 0x75e1237726b74fc9      0t0  TCP localhost:domain (LISTEN)

# It does serve queries on non loopback interfaces
# 192.168.2.242 is the address assigned on my machine in the Wi-Fi network
❯ dig @192.168.2.242 -p 53 www.google.com

; <<>> DiG 9.16.12 <<>> @192.168.2.242 -p 53 www.google.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55992
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www.google.com.                        IN      A

;; ANSWER SECTION:
www.google.com.         87      IN      A       216.58.194.196

;; Query time: 768 msec
;; SERVER: 192.168.2.242#53(192.168.2.242)
;; WHEN: Fri Mar 12 13:39:29 CST 2021
;; MSG SIZE  rcvd: 59

# And only UDP listening address is affected
❯ dig @192.168.2.242 -p 53 +tcp www.google.com
;; Connection to 192.168.2.242#53(192.168.2.242) for www.google.com failed: connection refused.

[ainar-g]

We had a very similar issue recently in #2623, but that one was about Big Sur. We'll investigate, thanks!

[EntropySmoke]

This may be related (or not). My Raspberry Pi DNS is set to 127.0.0.1 in dhcpd.conf, but AdGuardHome.yaml reports host bind on 0.0.0.0. Is this a correct configuration?

[EugeneOne1]

@laggardkernel, latest build was just pushed to the edge channel. Could you please check if it fixes the issue for you?

[EugeneOne1]

@laggardkernel, we'll close the issue for now. Please, feel free to reopen it if our solution won't fix it for you.

[laggardkernel]

@EugeneOne1 Yes. Tested with 0.107.0-b.7 and I can confirm the problem resolved. Thanks.