Mike's PBX Cookbook

Pi-hole and Unbound

With this setup, a DNS query traverses: Client ➤ Pi-hole ➤ Unbound ➤ DNS Root Server / TLD Server / authoritative name server

➤ Install Pi-hole (if not already):

curl -sSL https://install.pi-hole.net | bash

Follow the installation script, and confirm it works.

For local testing, you may want to install and use dig:

sudo apt install dnsutils
dig apple.com

At the end of the output, note: ;; SERVER: 192.168.178.2#53(192.168.178.2) - this is pi-hole responding on port 53 👍

➤ Install Unbound:

sudo apt install unbound

Download the current root hints file, this should be repeated every six months or so:

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

Create a configuration file: sudo nano /etc/unbound/unbound.conf.d/pi-hole.conf

and paste the following text into the file... 

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

    interface: 127.0.0.1
    interface: ::1
    port: 5335
    do-ip4: yes
    do-udp: yes
    do-tcp: yes

    # May be set to yes if you have IPv6 connectivity
    do-ip6: yes

    # 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: yes

    # 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.
    # Suggested by the unbound man page to reduce fragmentation reassembly problems
    edns-buffer-size: 1472

    # 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. 
    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

Save and exit with: Ctrl-o Ctrl-x, then restart unbound:

sudo service unbound restart

If unbound fails to start, investigate why with: systemctl status unbound.service

When unbound starts without error, test it:

dig apple.com @127.0.0.1 -p 5335

At the end of the output, note: ;; SERVER: 192.168.178.2#5335(192.168.178.2) - this is unbound (port 5335) 👍

➤ Back to Pi-hole. Either edit /etc/pihole/setupVars.conf to add the unbound server:

PIHOLE_DNS_1=127.0.0.1#5335
PIHOLE_DNS_2=::1#5335

Or open the pihole web page, and goto Settings ➤ DNS and add the unbound server: punbound.png

This Unbound configuration uses localhost#5335, we can also install NextDNS/Stubby on localhost#5353.

Note: