OpenVPN and DNS AdBlocking is a useful way to block ads on your smartphone without having to root it. This post describes how to setup such a service on your own server.

The idea is to set a DNS server in your OpenVPN DHCP options to push to clients. The DNS server runs in another Docker container and uses hosts files to block ads, trackers etc.

1. See https://www.digitalocean.com/community/tutorials/how-to-set-up-an-openvpn-server-on-ubuntu-14-04 as an example of how to set up an OpenVPN Docker container on a Ubuntu VPS. At the ovpn_genconfig step, set -n 8.8.8.8 so there is only a single placeholder DNS server to overwrite later on. Otherwise your settings will fallback to Google’s secondary DNS.

2. Setup the DNS container, this uses dnsmasq to block the bad hosts:

   git clone https://github.com/arthurkay/sagittarius-A && cd sagittarius-A && ./build.sh
   

   ``

3. Run the dnsmasq container:

   docker rm saga-dns; docker run --restart=always --name=saga-dns --expose 53 --cap-add=NET_ADMIN arthurkay/sagittarius-a &
   

   ``

We expose port 53 explicitly as the file does not currently contain an EXPOSE directive.

4. Run the OpenVPN container, linking to the saga-dns container:

   docker rm openvpn; docker run --restart=always --volumes-from ovpn-data --name openvpn --link saga-dns:saga-dns -p 1194:1194/udp --cap-add=NET_ADMIN kylemanna/openvpn bash -c 'sed -i -E "s/(push dhcp-option DNS).*/\1 $SAGA_DNS_PORT_53_TCP_ADDR/" /etc/openvpn/openvpn.conf && ovpn_run' &
   

   ``

This updates the saga-dns container’s IP in the OpenVPN config before running OpenVPN.

(Hopefully) enjoy much faster browsing and less tracking on your mobile devices.

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