Raspberry Pi 4 with Pi-Hole, OpenVPN and DNSCrypt

Raspberry Pi OS

Using Raspberry Pi OS, the official operating system for the Raspberry Pi, you can be sure that it is well optimized and supported for the Raspberry Pi.

Download Raspberry Pi Imager for an effortless way to install onto a Micro-SD card.

Update the system once the installation has been completed.

sudo apt uptdate && sudo apt -y upgrade
sudo apt install -y unattended-upgrades

Optional: Tweak Raspberry Pi OS

• sudo raspi-config
• 1 Change User Password
• 3 Boot Options - B1 Desktop / CLI - B2 Console Autologin
• 4 Localisation Options - I2 Change Timezone
• 4 Localisation Options - I4 Change Wi-Fi Country
• 7 Advanced Options - A1 Expand filesystem
• 7 Advanced Options - A3 Memory Split 16
• sudo shutdown -r now

Prep Work

Find the required IP addresses which will be needed for OpenVPN.

• External IP: curl ifconfig.me
• Internal IP: hostname -I

OpenVPN

VPN stands for Virtual Private Network. A VPN creates an encrypted tunnel between the client and a VPN server. All the internet data is routed through this tunnel, so the data is secure from any man in the middle attacks.

Another benefit of a VPN is, is that it allows clients to remotely access the local network securely.

Install

wget https://git.io/vpn -O openvpn-install.sh
chmod 755 openvpn-install.sh
sudo ./openvpn-install.sh

Example Install Settings

• Public IPv4 address / hostname []: 123.456.789.000
• Protocol [1]: UDP
• Port [1194]: 11948
• DNS [1]: Current system resolvers
• Client name [client]: my-phone

The generated opvn file can be used with an OpenVPN client on e.g. a cell phone. It can be found inside the /root directory, in my case /root/my-phone.ovpn. I copy this over to the home directory ~/ for easy transferring it off the Raspberry Pi using SFTP.

Configure OpenVPN

First, find out the tun0 interface IP address which is what OpenVPN uses using the command ifconfig tun0 | grep 'inet'. In my case, it is 10.8.0.1.

• Edit OpenVPN server config:
  sudo nano /etc/openvpn/server/server.conf
• Add the tun0 interface IP address, PiHole will be using it:
  push "dhcp-option DNS 10.8.0.1"
• Comment out other dhcp-option references by adding a # in front of it:
  #push "dhcp-option DNS 192.168.1.1"
• Restart OpenVPN server:
  sudo systemctl restart openvpn

DNSCrypt

It is a protocol that authenticates communications between a DNS client and a DNS resolver. It prevents DNS spoofing. It uses cryptographic signatures to verify that responses originate from the chosen DNS resolver and haven’t been tampered with.

Install

Install DNSCrypt-Proxy into the directory /opt, which is for installation of add-on application software packages.

cd /opt
sudo wget https://github.com/DNSCrypt/dnscrypt-proxy/releases/download/2.1.1/dnscrypt-proxy-linux_arm-2.1.1.tar.gz
sudo tar xf dnscrypt-proxy-linux_arm-2.1.1.tar.gz
sudo rm dnscrypt-proxy-linux_arm-2.1.1.tar.gz
sudo mv linux-arm dnscrypt-proxy
cd dnscrypt-proxy
sudo cp example-dnscrypt-proxy.toml dnscrypt-proxy.toml

Configure DNSCrypt

For DNSCrypt-proxy to work correctly alongside Pi-Hole some changes must be made to the configuration file dnscrypt-proxy.toml.

Open dnscrypt-proxy.toml by running the command sudo nano dnscrypt-proxy.toml while still in /opt/dnscrypt-proxy.

• Change port, since 53 is already being used by Pi-Hole.
  This is the listen_addresses line.
  Change it to listen_addresses = ['127.0.0.1:54','[::1]:54']
• Change require_dnssec = false to require_dnssec = true
• Install the dnscrypt-proxy service.
  sudo ./dnscrypt-proxy -service install
• Start the dnscrypt-proxy service.
  sudo ./dnscrypt-proxy -service start
• Check the service status.
  sudo systemctl status dnscrypt-proxy

Feel free to change additional options inside the configuration file to suit your needs as I have done.

Pi-Hole

At the installation pick whatever upstream DNS server. Modify it later in the configuration file.

wget -O basic-install.sh https://install.pi-hole.net
sudo bash basic-install.sh

Take note of the login password once the installation is complete.

Configure Pi-Hole

Add the DNSCrypt-Proxy server to Pi-Hole on the Pi-Hole admin page.

Configure Clients

Configure clients to use the Pi-Hole IP address as the DNS server or configure the router so that every client on the local network will be using Pi-Hole filtering while being DNSCrypt secured.