🤖 Boost Pi-hole Performance with Unbound DNS Resolver

If you're looking to boost the performance and security of your Pi-hole setup, installing Unbound is a great choice.

Unbound, a highly efficient DNS resolver, specializes in bolstering the security measures associated with domain-to-IP address translations. Notably, it employs robust encryption protocols such as DNS-over-TLS and DNS-over-HTTPS, significantly enhancing the confidentiality and integrity of DNS queries. Emphasizing DNSSEC (Domain Name System Security Extensions), Unbound authenticates and validates DNS data, mitigating risks related to DNS spoofing and tampering. Its open-source nature fosters continual improvements and transparency within the cyber-security community, making it a reliable choice for enhancing the safety and reliability of domain-to-IP translations.

For more details, refer to the Unbound - Pi-hole documentation.

» Step 1: Prerequisites

a) Before initiating the installation process, ensure you have the following:

A Raspberry Pi or another device running Pi-hole
Access to the terminal or SSH

b) Update your system

Ensure your system is up-to-date by executing the following commands:

sudo apt update && sudo apt upgrade

» Step 2 (optional): Remove unnecessary APT dependencies

Would you like to free up space on your hard drive? You can achieve this by running the following command, which will remove unnecessary dependencies.

sudo apt autoremove

» Step 2: Install Unbound

To install Unbound, execute the following command:

sudo apt install unbound

After installation, you may likely encounter a startup error for the Unbound service. Ignore this.

» Step 3: Download the current root hints file

wget https://www.internic.net/domain/named.root -qO- | sudo tee /var/lib/unbound/root.hints

Update it approximately every six months! Keep in mind that this file changes infrequently.

Cron

If you're unable or unwilling to update this file regularly, you can add a new cron job.

Enter the command sudo sudo crontab -e to edit the crontab file. In this specific case, remember to prefix crontab -e with sudo to ensure the cron job has the necessary permissions.

Paste the new Cron job into the file:

30 6 1 * * wget -qO- https://www.internic.net/domain/named.root | sudo tee /var/lib/unbound/root.hints >/dev/null 2>&1

Remember to add a new line at the bottom of the file.

Save the file. To start from now on, your device will update the file automatically at 06:30 every first day of the month.

» Step 4: Configure Unbound

With Unbound installed, you need to configure it to work with Pi-hole by running the following command:
```
sudo nano /etc/unbound/unbound.conf.d/pi-hole.conf
```

Paste the following configuration into the file:

Click here to show the content of the `conf` file

server:
   # If no logfile is specified, syslog is used
   # logfile: "/var/log/unbound/unbound.log"
   verbosity: 0

   interface: 127.0.0.1
   port: 5335
   do-ip4: yes
   do-udp: yes
   do-tcp: yes

   # May be set to yes if you have IPv6 connectivity
   do-ip6: no

   # You want to leave this to no unless you have *native* IPv6. With 6to4 and
   # Terredo tunnels your web browser should favor IPv4 for the same reasons
   prefer-ip6: no

   # Use this only when you downloaded the list of primary root servers!
   # If you use the default dns-root-data package, unbound will find it automatically
   root-hints: "/var/lib/unbound/root.hints"

   # Trust glue only if it is within the server's authority
   harden-glue: yes

   # Require DNSSEC data for trust-anchored zones, if such data is absent, the zone becomes BOGUS
   harden-dnssec-stripped: yes

   # Don't use Capitalization randomization as it known to cause DNSSEC issues sometimes
   # see https://discourse.pi-hole.net/t/unbound-stubby-or-dnscrypt-proxy/9378 for further details
   use-caps-for-id: no

   # Reduce EDNS reassembly buffer size.
   # IP fragmentation is unreliable on the Internet today, and can cause
   # transmission failures when large DNS messages are sent via UDP. Even
   # when fragmentation does work, it may not be secure; it is theoretically
   # possible to spoof parts of a fragmented DNS message, without easy
   # detection at the receiving end. Recently, there was an excellent study
   # >>> Defragmenting DNS - Determining the optimal maximum UDP response size for DNS <<<
   # by Axel Koolhaas, and Tjeerd Slokker (https://indico.dns-oarc.net/event/36/contributions/776)
   # in collaboration with NLnet Labs explored DNS using real world data from the
   # the RIPE Atlas probes and the researchers suggested different values for
   # IPv4 and IPv6 and in different scenarios. They advise that servers should
   # be configured to limit DNS messages sent over UDP to a size that will not
   # trigger fragmentation on typical network links. DNS servers can switch
   # from UDP to TCP when a DNS response is too big to fit in this limited
   # buffer size. This value has also been suggested in DNS Flag Day 2020.
   edns-buffer-size: 1232

   # Perform prefetching of close to expired message cache entries
   # This only applies to domains that have been frequently queried
   prefetch: yes

   # One thread should be sufficient, can be increased on beefy machines.
   # In reality for most users running on small networks or on a single machine, it should be unnecessary to seek performance enhancement by increasing num-threads above 1.
   num-threads: 1

   # Ensure kernel buffer is large enough to not lose messages in traffic spikes
   so-rcvbuf: 1m

   # Ensure privacy of local IP ranges
   private-address: 192.168.0.0/16
   private-address: 169.254.0.0/16
   private-address: 172.16.0.0/12
   private-address: 10.0.0.0/8
   private-address: fd00::/8
   private-address: fe80::/10

» Step 5: Restart Unbound

To apply the changes, restart Unbound by running the following commands:

sudo service unbound restart

» Step 6: Test Unbound

Verify Unbound's functionality with the following command:

dig sefinek.net @127.0.0.1 -p 5335

Upon running the command, you should receive a response similar to:

; <<>> DiG 9.16.1-Ubuntu <<>> sefinek.net @127.0.0.1 -p 5335
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6319
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;sefinek.net.                   IN      A

;; ANSWER SECTION:
sefinek.net.            255     IN      A       188.114.97.11
sefinek.net.            255     IN      A       188.114.96.11

;; Query time: 4 msec
;; SERVER: 127.0.0.1#5335(127.0.0.1)
;; WHEN: Sat Nov 25 06:21:25 CET 2023
;; MSG SIZE  rcvd: 72

This output indicates successful resolution of the sefinek.net domain to its corresponding IP addresses (188.114.97.11 and 188.114.96.11). Confirming this result means Unbound is operating as expected.

Yay! We've successfully obtained the IP address for sefinek.net!

» Step 6: Configure Pi-hole to use Unbound

Open the Pi-hole web interface in your browser.
Log in to the dashboard.
Navigate to Settings and then DNS.
Scroll down and append 127.0.0.1#5335 to the Custom DNS servers field.
Save & Apply

» Step 7: Final tests

It's vital to ensure that everything is operating flawlessly. You can verify the functionality of your DNS resolver by visiting https://d3ward.github.io/toolz/adblock.html. This tool helps test the effectiveness of your ad-blocking setup.