dnsmasq: failed to create listening socket for port 53: Address already in use

Question

I got this error when i done the setup dnsmasq.

ashokkrishna@krishna:~$ sudo dnsmasq

dnsmasq: failed to create listening socket for port 53: Address already in use


ashokkrishna@krishna:~$ netstat -lpn | grep :53
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 0.0.0.0:53              0.0.0.0:*               LISTEN      -               
tcp6       0      0 :::53                   :::*                    LISTEN      -               
tcp6       0      0 :::53755                :::*                    LISTEN      -               
udp        0      0 0.0.0.0:53              0.0.0.0:*                           -               
udp        0      0 0.0.0.0:5353            0.0.0.0:*                           -               
udp6       0      0 :::53                   :::*                                -               
udp6       0      0 :::5353                 :::*                                - 

so how to solve this or how to stop those sockets.

Answer 1

You can do this:

netstat -tupln

you will get result like this:

tcp   0  0 :::80   :::*      LISTEN    713/httpd

take the pid for the process that listening on th port 53 and kill it with this command

kill -9 pid

Answer 2

I just spent hours trying to resolve this issue in a reasonable manner without any major system modifications.

Stop dnsmasq from auto starting.

servicectl disable dnsmasq

Create file /etc/rc.local or /etc/rc.d/rc.local depending on distro.

Set perms chmod +x /etc/rc.local

Edit file:

#!/bin/bash
service systemd-resolved stop
service dnsmasq start

Simply stopping systemd-resolved then starting dnsmasq after full boot works perfect, at least on Mint. I can't speak on other distros.

Answer 3

Check for port usage with;

lsof -i -n -P

In my case, systemd-resolved was blocking port 53 from use as below:

systemd-r  640 systemd-resolve   12u  IPv4  22295      0t0  UDP 127.0.0.53:53
systemd-r  640 systemd-resolve   13u  IPv4  22296      0t0  TCP 127.0.0.53:53 (LISTEN)

Simply disable systemd-resolved before enabling dnsmasq;

sudo systemctl disable systemd-resolved --now
sudo systemctl enable dnsmasq --now