Unbound has a vast array of configuration options for advanced use cases, which can seem a little overwhelming at first. Luckily, all of the defaults are sensible and secure, so in a lot of environments you can run Unbound without changing any options. Below we will go through a basic, recommended configuration, but feel free to add and experiment with options as you need them.
The instructions in this page assume that Unbound is already installed.
The basic configuration which you can use out of the box is shown below. To use it, you need to create a file with this configuration as its content (or copy the configuration to the default configuration file which can be found during the installation process).
server: # can be uncommented if you do not need user privilige protection # username: "" # can be uncommented if you do not need file access protection # chroot: "" # location of the trust anchor file that enables DNSSEC. note that # the location of this file can be elsewhere auto-trust-anchor-file: "/usr/local/etc/unbound/root.key" # auto-trust-anchor-file: "/var/lib/unbound/root.key" # send minimal amount of information to upstream servers to enhance privacy qname-minimisation: yes # specify the interface to answer queries from by ip-address. interface: 0.0.0.0 # interface: ::0 # addresses from the IP range that are allowed to connect to the resolver access-control: 192.168.0.0/16 allow # access-control: 2001:DB8/64 allow
By default the Unbound configuration uses
chroot to provide an extra layer
of defence against remote exploits.
If Unbound is not starting because it cannot access files due to permission
errors caused by chroot, a solution can be to enter file paths as
full pathnames starting at the root of the file system (
Otherwise, if chroot is not required you can disable it in the
server: # disable chroot chroot: ""
By default Unbound assumes that a user named “unbound” exists.
You can add this user with an account management tool available on your system;
on Linux this is usually useradd).
You can also disable this feature by adding
username: "" in the
server: # disable user privilige protection username: ""
If it is enabled, after the setup, any other user privileges are dropped and
the configured username is assumed.
If this user needs access to files (such as the ‘trust
anchor’ mentioned below), these can be created by executing with
unbound in front of it.
Unbound comes with the unbound-checkconf(8) tool. This tool allows you to check the config file for errors before starting Unbound. It is very convenient because if any errors are found it tells you where they are, which is particularly useful when Unbound is already running to avoid failure to restart due to a configuration error.
Testing the setup¶
After running the unbound-checkconf command to see if your config
file is correct, you can test your setup by running Unbound in “debug” mode.
This allows you to see what is happening during startup and catch any errors.
The unbound(8) manpage shows that the
flag will start Unbound in this mode.
The manpage also shows that we can use the
-c flag to
specify the path to the configuration file, so we can use the one we created.
We also recommend increasing the verbosity of the logging to 1 or 2, to see
what’s actually happening (
unbound -d -vv -c unbound.conf
After Unbound starts normally (and you’ve sent it some queries) you can remove
-d and run the command
Then Unbound will fork to the background and run until you either kill it or
reboot the machine.
Set up Remote Control¶
A useful functionality to enable is the unbound-control(8) command. This makes starting, stopping, and reloading Unbound easier. To enable this functionality we need to add remote-control: to the configuration file:
remote-control: # enable remote-control control-enable: yes # location of the files created by unbound-control-setup # server-key-file: "/usr/local/etc/unbound/unbound_server.key" # server-cert-file: "/usr/local/etc/unbound/unbound_server.pem" # control-key-file: "/usr/local/etc/unbound/unbound_control.key" # control-cert-file: "/usr/local/etc/unbound/unbound_control.pem"
To use the unbound-control command, we need to invoke the
unbound-control-setup command. This creates a number of files in the
default install directory. The default install directory is
/usr/local/etc/unbound/ on most systems, but some distributions may put it
Apart from an extensive configuration file, with just about all the possible configuration options, unbound-control-setup creates the cryptographic keys necessary for the control option:
If you use a username like
unbound in the configuration to run the daemon
(which is the default setting), you can use sudo to create the files
in that user’s name, so that the user running Unbound is allowed to read the
This is also a solution if the
/usr/local/etc/unbound/ directory (or any
other default directory) is write-protected, which is the case for some
sudo -u unbound unbound-control-setup
You can now control Unbound using the unbound-control command. Note
that if your configuration file is not in the default location or not named
unbound.conf, the name (and possibly path) need to be provided when using
the command using the
Set up Trust Anchor (Enable DNSSEC)¶
To enable DNSSEC, which we strongly recommend, we need to set up a trust anchor as it allows the verification of the integrity of the responses to the queries you send.
To help, we can use the unbound-anchor(8) command.
unbound-anchor performs the setup by configuring a trust anchor. This
trust anchor will only serve as the initial anchor from builtin values. To keep
this anchor up to date, Unbound must be able to read and write to this file. The
default location that unbound-anchor creates this in is determined by
your installation method.
Usually the default directory is
Note that using a package manager to install Unbound, on some distributions,
creates the root key during installation. On Ubuntu 20.04.1 LTS for example,
this location is
/var/lib/unbound/root.key. On macOS Big Sur this location
/opt/homebrew/etc/unbound/root.key If you create the root key yourself
(by using the unbound-anchor command), then the path to the anchor
file in the configuration file should be changed to the correct location. To
find out the default location you can use the unbound-anchor command
again with the
-vvv option enabled. To enable DNSSEC, we add
auto-trust-anchor-file under the
server clause in the configuration
server: # enable DNSSEC auto-trust-anchor-file: "/var/lib/unbound/root.key"
Note that on some systems the
/usr/local/etc/unbound/ directory might be
If the unbound-control-setup command fails due to the insufficient
permissions, run the command as the correct user, here we use the user
unbound as this is the default user.
sudo -u unbound unbound-anchor
This step is also important when using the