Ad Blocking, Local Recursive DNS Server with Pi-Hole and Unbound

How to get a pi-hole DNS server up and running the right way. Normally I just used it as an add-blocker, but it can also be a recursive DNS server. This is what 1.1.1.1, 8.8.8.8, and your ISP's DNS servers are.

Ian Cleary

Posted: Saturday, January 30, 2021

3 min read

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How to get a pi-hole DNS server up and running the right way.

Normally I just used it as an add-blocker, but it can also be a recursive DNS server. This is what 1.1.1.1, 8.8.8.8, and your ISP's DNS servers are.

A video tutorial by Craft Computing is below:

Pre-Requisites

Set up a Ubuntu 20.04 Server on your local network. Find it's IP address and SSH into it.

Procedure

We will:

  • Install Ubuntu Server 20.04 (https://ubuntu.com/download/server)

  • Install Pi-Hole sudo with curl -sSL https://install.pi-hole.net | bash

  • Set the Web Admin Password - pihole -a -p [password]

  • Install Unbound DNS - sudo apt install unbound

  • Create Unbound Configuration File - sudo nano /etc/unbound/unbound.conf.d/pi-hole.conf

  • Copy example config https://docs.pi-hole.net/guides/dns/unbound/

    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.
      # 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. 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
    

Restart Unbound to apply Configuration

sudo service unbound restart

Disable Forwarding DNS in PiHole

Set Custom DNS in PiHole - 127.0.0.1#5335

Pi Hole Custom DNS Screen showing "Custom 1 (IPv4)" Unbound DNS as Upstream DNS Server

Setup Router to use Pi-Hole IP Address as only DNS server (varies for your DHCP server on your router)

Enjoy your private, ad-blocking, self hosted recursive DNS server!