Own Your DNS Data

Although many people assume very little privacy at work, home is a different matter. At home, you are most likely to use the DNS servers your ISP provided you, while others use Google's DNS servers because the IPs are easy to remember. This means even if others can't intercept your traffic (maybe you are sending it through a VPN, or maybe that kind of line tapping simply requires more legal standing), if they can get access to your DNS logs (I could see some arguing that this qualifies as metadata), they would have a fairly complete view of all the sites you visit without your ever knowing.

This is not just valuable data from a surveillance standpoint, or a privacy standpoint, but also from a marketing standpoint. Even if you may be fine with the government knowing what porn sites you browse, where you shop, where you get your news and what e-mail provider you use, you may not want a marketing firm to have that data.

Recursive DNS vs. DNS Caching

The key to owning your DNS data and keeping it private is to run your own DNS server and use it for all of your outbound DNS queries. Although many people already run some sort of DNS caching programs, such as dnsmasq to speed up DNS queries, what you want isn't simply a DNS cache, but something that can function as a recursive DNS resolver. In the case of dnsmasq, it is configured to use upstream recursive DNS servers to do all of the DNS heavy lifting (the documentation recommends you use whatever DNS servers you currently have in /etc/resolv.conf). Thus, all of your DNS queries for www.linuxjournal.com go to your DNS caching software and then are directed to, for instance, your ISP's DNS servers before they do the traditional recursive DNS procedure of starting at root name servers, then going to com, then finally to the name servers for linuxjournal.com. So, all of your queries still get logged at the external recursive DNS server.

What you want is a local DNS service that can do the complete recursive DNS query for you. In the case of a request for www.linuxjournal.com, it would communicate with the root, com and linuxjournal.com name servers directly without an intermediary and ultimately cache the results like any other DNS caching server. For outside parties to capture all of your DNS logs, they either would have to compromise your local, personal DNS server on your home network, set up a tap to collect all of your Internet traffic or set up a tap at all the root name servers. All three of these options are either illegal or require substantial court oversight.


Kyle Rankin is Chief Security Officer at Purism, a company focused on computers that respect your privacy, security, and freedom. He is the author of many books including Linux Hardening in Hostile Networks, DevOps Troubleshooting and The Official Ubuntu