Solving the 53 Port Occupancy Issue on Ubuntu

Recently, in order to install a DoH Client on my router and set up a DNS server for internal network devices, I found that Ubuntu often uses port 53.

After checking, I found that this was caused by systemd-resolve, so I found these methods to disable it!

Before that, if you find that port 53 is being used, you can use the following command to see which process is using it.

sudo netstat -pna | grep 53

Then, let’s solve the problem of systemd-resolve using port 53.

First, we edit the /etc/systemd/resolved.conf file.

sudo vi /etc/systemd/resolved.conf

We uncomment the line DNSStubListener and change it to No.

[Resolve]
#DNS=
#FallbackDNS=
#Domains=
#LLMNR=no
#MulticastDNS=no
#DNSSEC=no
#DNSOverTLS=no
#Cache=yes
DNSStubListener=no
#ReadEtcHosts=yes

Then, enter this command.

sudo ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf

Finally, we restart the systemd-resolved service.

sudo systemctl restart systemd-resolved

Now, we can use port 53!