Change a machine's DNS server

Changing the DNS server of a linux machine is needlessly complicated, so this guide is sadly necessary.

For a full list of DNS see the Adguard DNS web page that lists all the relevant one https://adguard-dns.io/kb/general/dns-providers/

This guide will use the Adguard non-filtering servers, because it's basically the best (Quad9 is also good, but has a tendency to make some application bug out... maybe because of a strong rate limit)

/etc/network/interfaces¶

Edit the network interfaces file:

sudo nano /etc/network/interfaces

Find the section for your network interface (usually named eth0 for wired or wlan0 for wireless) and add or edit the dns-nameservers line to include your desired DNS servers. For example:

dns-nameservers 94.140.14.140 94.140.14.141

Replace 94.140.14.140 and 94.140.14.141 with the IP addresses of the DNS servers you want to use. Separate multiple DNS servers with a space.

/etc/resolv.conf¶

Edit the resolv.conf file:

Note that this file might be automatically overwritten by network manager tools (still, it's recommended to edit it in case none of the network manager tools do their job).

sudo nano /etc/resolv.conf

Add or edit the nameserver line to include your desired DNS servers. For example:

nameserver 94.140.14.140
nameserver 94.140.14.141

Replace 94.140.14.140 and 94.140.14.141 with the IP addresses of the DNS servers you want to use. One line = one DNS server

Stop dhclient from modifying /etc/resolv.conf¶

If you have dhclient installed (default on Debian) you have to make it so it doesn't touch /etc/resolv.conf

echo 'make_resolv_conf() { :; }' > /etc/dhcp/dhclient-enter-hooks.d/leave_my_resolv_conf_alone
chmod 755 /etc/dhcp/dhclient-enter-hooks.d/leave_my_resolv_conf_alone

(taken from https://wiki.debian.org/resolv.conf )

Systemd-networkd and Systemd-resolved (optional)¶

Some distro uses systemd-networkd and systemd-resolved and those are unnecessarily awful to configure (since the previous 2 files takes precedent, meaning that you basically have 4 files to edit if you use them).

/etc/systemd/network/*.network¶

Open the existing file (if it exists):

sudo nano /etc/systemd/network/*.network

Edit the DNS line under [Network]:

[Network]
DNS=94.140.14.140 94.140.14.141

Replace 94.140.14.140 and 94.140.14.141 with the IP addresses of the DNS servers you want to use. Separate multiple DNS servers with a space.

/etc/systemd/resolved.conf¶

Note: if all the lines of the files are commented, it shouldn't be necessary to edit it since the first two files will keep "control".

sudo nano /etc/systemd/resolved.conf

Edit the DNS line under [Resolve]:

[Resolve]
DNS=94.140.14.140 94.140.14.141

Replace 94.140.14.140 and 94.140.14.141 with the IP addresses of the DNS servers you want to use. Separate multiple DNS servers with a space.

Applying the changes (if you don't reboot)¶

Restart networking:

After editing the file, restart networking for the changes to take effect:

$ sudo systemctl daemon-reload
$ sudo systemctl restart systemd-networkd
$ sudo systemctl restart systemd-resolved
$ sudo systemctl restart networking

The end¶

It is strongly recommended that you reboot (and check that the change is still in place) after that, however it shouldn't be mandatory.