Solution

It was found (here, and here) that Podman uses its own DNS server, aardvark-dns which is bound to port 53 (this explains why I was able to bind to 53 with nc on the host while the container would still fail). So the solution is to bridge the network for that port. So, in the compose file, the ports section would become:

ports:
  - "<host-ip>:53:53/tcp"
  - "<host-ip>:53:53/udp"
  - "80:80/tcp"

where <host-ip> is the ip of the machine running the container — e.g. 192.168.1.141.


Original Post

I so desperately want to bash my head into a hard surface. I cannot figure out what is causing this issue. The full error is as follows:

Error: cannot listen on the UDP port: listen udp4 :53: bind: address already in use

This is my compose file:

version: "3"
services:
  pihole:
    container_name: pihole
    image: docker.io/pihole/pihole:latest
    ports:
      - "53:53/tcp"
      - "53:53/udp"
      - "80:80/tcp"
    environment:
      TZ: '<redacted>'
    volumes:
      - './etc-pihole:/etc/pihole'
      - './etc-dnsmasq.d:/etc/dnsmasq.d'
    restart: unless-stopped

and the result of # ss -tulpn:

Netid       State        Recv-Q       Send-Q                             Local Address:Port               Peer Address:Port       Process                                         
udp         UNCONN       0            0                    [fe80::e877:8420:5869:dbd9]:546                           *:*           users:(("NetworkManager",pid=377,fd=28))       
tcp         LISTEN       0            128                                      0.0.0.0:22                      0.0.0.0:*           users:(("sshd",pid=429,fd=3))                  
tcp         LISTEN       0            128                                         [::]:22                         [::]:*           users:(("sshd",pid=429,fd=4))        

I have looked for possible culprit services like systemd-resolved. I have tried disabling Avahi. I have looked for other potential DNS services. I have rebooted the device. I am running the container as sudo (so it has access to all ports). I am quite at a loss.

  • Raspberry Pi Model 1 B Rev 2
  • Raspbian (bookworm)
  • Kernel v6.6.20+rpt-rpi-v6
  • Podman v4.3.1
  • Podman Compose v1.0.3

EDIT (2024-03-14T22:13Z)

For the sake of clarity, # netstat -pna | grep 53 shows nothing on 53, and # lsof -i -P -n | grep LISTEN shows nothing listening to port 53 — the only listening service is SSH on 22, as expected.

Also, as suggested here, I tried manually binding to port 53, and I was able to without issue.

  • Climatic2469@lemmy.world
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    10 months ago

    In the /etc/systemd/resolved.conf

    Set the DNSStubListener=no like below then restart the network resolvd service this should allow you to run an alternate service on port 53

    #  This file is part of systemd.
    #
    #  systemd is free software; you can redistribute it and/or modify it under the
    #  terms of the GNU Lesser General Public License as published by the Free
    #  Software Foundation; either version 2.1 of the License, or (at your option)
    #  any later version.
    #
    # Entries in this file show the compile time defaults. Local configuration
    # should be created by either modifying this file, or by creating "drop-ins" in
    # the resolved.conf.d/ subdirectory. The latter is generally recommended.
    # Defaults can be restored by simply deleting this file and all drop-ins.
    #
    # Use 'systemd-analyze cat-config systemd/resolved.conf' to display the full config.
    #
    # See resolved.conf(5) for details.
    
    [Resolve]
    # Some examples of DNS servers which may be used for DNS= and FallbackDNS=:
    # Cloudflare: 1.1.1.1#cloudflare-dns.com 1.0.0.1#cloudflare-dns.com 2606:4700:4700::1111#cloudflare-dns.com 2606:4700:4700::1001#cloudflare-dns.com
    # Google:     8.8.8.8#dns.google 8.8.4.4#dns.google 2001:4860:4860::8888#dns.google 2001:4860:4860::8844#dns.google
    # Quad9:      9.9.9.9#dns.quad9.net 149.112.112.112#dns.quad9.net 2620:fe::fe#dns.quad9.net 2620:fe::9#dns.quad9.net
    DNS=127.0.0.1
    #FallbackDNS=
    #Domains=
    #DNSSEC=no
    #DNSOverTLS=no
    #MulticastDNS=no
    #LLMNR=no
    #Cache=no-negative
    #CacheFromLocalhost=no
    DNSStubListener=no
    #DNSStubListenerExtra=
    #ReadEtcHosts=yes
    #ResolveUnicastSingleLabel=no
    
    • Kalcifer@sh.itjust.worksOP
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      10 months ago

      systemd-resolved is not running ­— it isn’t even installed on the device. I also already mentioned that I have looked into this fact within the body of the post.

      • Climatic2469@lemmy.world
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        10 months ago

        That wasn’t clear from the body, as it says you investigated systemd but hadn’t resolved the issue. I’m glad you found a solution though and have a good day.

    • Telodzrum@lemmy.world
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      10 months ago

      This is the correct solution. OP’s issue is a common one which shows up on the PiHole discussion forums regularly. I frequently forget to perform this step on new installs, too.

      • Kalcifer@sh.itjust.worksOP
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        10 months ago

        This is the correct solution.

        No it isn’t. systemd-resolved is not running ­— it isn’t even installed on the device. I also already mentioned that I have looked into this fact within the body of the post.