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I am trying to have an authoritative only Bind server inside a LXC container but when I went to forward the port 53 to it, I received an error saying the port is already in use. (listen=tcp:0.0.0.0:53 connect=tcp:127.0.0.1:53)

After researching I understood that dnsmasq/netplan/systemd-resolve (don't really know which one) is responsible for the container name resolution.

COMMAND    PID            USER   FD   TYPE DEVICE SIZE/OFF NODE NAME    
systemd-r  608 systemd-resolve   13u  IPv4  21646      0t0  TCP localhost:domain (LISTEN)    
dnsmasq   6667             lxd    9u  IPv4 103653      0t0  TCP v2202102:domain (LISTEN)    
dnsmasq   6667             lxd   11u  IPv6 103655      0t0  TCP v2202102:domain (LISTEN)

Does anyone have any idea on what I could do to solve this? I thought about the following:

  • Disabling dnsmasq but then I won't get the name resolution from the containers anymore...

  • Disabling dnsmasq and let Bind resolve the names - No clue on how to do that..

  • Changing dnsmasq port - I have no clue on how to do that and ensure the container resolution keeps working

  • Other ideas are welcome :)

I am using Ubuntu 20.04 with LXD 4.xxx

Thanks in advance.

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Thank you for the help! Bind forwarding to dnsmasq looks to me the ideal approach but unfortunately I couldn't find the dnsmasq configuration file and when using systemctl status dnsmasq it says it isn't installed LOL... quite weird if you ask me.

I ended up with a less intrusive approach, which is listening just to my external_IP_address:53 instead of the whole 0.0.0.0:53 as I was trying before.

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