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
sudo vi /etc/systemd/resolved.conf
We uncomment the line
DNSStubListener and change it to
[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
sudo systemctl restart systemd-resolved
Now, we can use port 53!