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DNS firewall rules

After you have been diligent enough to configure pfSense to act as a DNS server, it would be a shame if end users on your network could circumvent pfSense and specify whatever DNS server they want. Yet that’s exactly what most modern OSes allow the end user to do. The following screenshot shows part of the IPv4 configuration page in a recent version of Mint Linux:

Circumventing the network DNS policy by changing the DNS server in Mint Linux

As you can see, the end user has disabled automatic DNS configuration and specified one of the Google DNS servers instead. Thus, even if we have set up pfSense to act as the DNS server ...

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