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Dns-rev-1-wikimedia.gifIn 2014, six months after the Snowden revelations, engineers began discussing how to harden the Internet against passive pervasive surveillance. Among the results have been efforts like Let's Encrypt, EFF's Privacy Badger, and HTTPS Everywhere. Real inroads have been made into closing some of the Internet's affordances for surveillance and improving security for everyone.

Arguably the biggest remaining serious hole is the domain name system, which was created in 1983. The DNS's historical importance is widely underrated; it was essential in making email and the web usable enough for mass adoption before search engines. Then it stagnated. Today, this crucial piece of Internet infrastructure still behaves as if everyone on the Internet can trust each other. We know the Internet doesn't live there any more; in February the Internet Corporation for Assigned Names and Numbers, which manages the DNS, warned of large-scale spoofing and hijacking attacks. The NSA is known to have exploited it, too.

The problem is the unprotected channel between the computer into which we type humanly-readable names such as pelicancrossing.net and the computers that translate those names into numbered addresses the Internet's routers understand, such as The fact that routers all trust each other is routinely exploited for the captive portals we often see when we connect to public wi-fi systems. These are the pages that universities, cafes, and hotels set up to redirect Internet-bound traffic to their own page so they can force us to log in, pay for access, or accept terms and conditions. Most of us barely think about it, but old-timers and security people see it as a technical abuse of the system.

Several hijacking incidents raised awareness of DNS's vulnerability as long ago as 1998, when security researchers Matt Blaze and Steve Bellovin discussed it at length at Computers, Freedom, and Privacy. Twenty-one years on, there have been numerous proposals for securing the DNS, most notably DNSSEC, which offers an upwards chain of authentication. However, while DNSSEC solves validation, it still leaves the connection open to logging and passive surveillance, and the difficulty of implementing it has meant that since 2010, when ICANN signed the global DNS root, uptake has barely reached14% worldwide.

In 2018, the IETF adopted DNS-over-HTTPS as a standard. Essentially, this sends DNS requests over the same secure channel browsers use to visit websites. Adoption is expected to proceed rapidly because it's being backed by Mozilla, Google, and Cloudflare, who jointly intend to turn it on by default in Chrome and Firefox. In a public discussion at this week's Internet Service Providers Association conference, a fellow panelist suggested that moving DNS queries to the application level opens up the possibility that two different apps on the same device might use different DNS resolvers - and get different responses to the same domain name.

Britain's first public notice of DoH came a couple of week ago in the Sunday Times, which billed it as Warning over Google Chrome's new threat to children. This is a wild overstatement, but it's not entirely false: DoH will allow users to bypass the parts of Britain's filtering system that depend on hijacking DNS requests to divert visitors to blank pages or warnings. An engineer would probably argue that if Britain's many-faceted filtering system is affected it's because the system relies on workarounds that shouldn't have existed in the first place. In addition, because DoH sends DNS requests over web connections, the traffic can't be logged or distinguished from the mass of web traffic, so it will also render moot some of the UK's (and EU's) data retention rules.

For similar reasons, DoH will break captive portals in unfriendly ways. A browser with DoH turned on by default will ignore the hotel/cafe/university settings and instead direct DNS queries via an encrypted channel to whatever resolver it's been set to use. If the network requires authentication via a portal, the connection will fail - a usability problem that will have to be solved.

There are other legitimate concerns. Bypassing the DNS resolvers run by local ISPs in favor of those belonging to, say, Google, Cloudflare, and Cisco, which bought OpenDNS in 2015, will weaken local ISPs' control over the connections they supply. This is both good and bad: ISPs will be unable to insert their own ads - but they also can't use DNS data to identify and block malware as many do now. The move to DoH risks further centralizing the Internet's core infrastructure and strengthening the power of companies most of us already feel have too much control.

The general consensus, however, is that like it or not, this thing is coming. Everyone is still scrambling to work out exactly what to think about it and what needs to be done to mitigate accompanying risks, as well as find solutions to the resulting problems. It was clear from the ISPA conference panel that everyone has mixed feelings, though the exact mix of those feelings and which aspects are identified as problems - differ among ISPs, rights activists, and security practitioners. But it comes down to this: whether you like this particular proposal or not, the DNS cannot be allowed to remain in its present insecure state. If you don't want DoH, come up with a better proposal.

Illustrations: DNS diagram (via Б.Өлзий at Wikimedia.

Wendy M. Grossman is the 2013 winner of the Enigma Award. Her Web site has an extensive archive of her books, articles, and music, and an archive of earlier columns in this series. Stories about the border wars between cyberspace and real life are posted occasionally during the week at the net.wars Pinboard - or follow on Twitter.


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