DNS Over TLS on OpenWrt 18.06

DNS over TLS encrypts DNS queries so no one between you and the DNS server you’re using (which, by default using these steps, will be Cloudflare’s 1.1.1.1), can tell what DNS queries/responses are being exchanged.

DNS over TLS provides confidentiality but not integrity or authenticity. For those, you need to setup DNSSEC which I’ve described how to do on OpenWrt in another post.

By setting up DNS over TLS on your OpenWrt router, you protect your entire network as all clients will perform DNS requests using your OpenWrt router’s DNS server which in turn will use DNS over TLS to perform the actual resolution.

Setting up DNS over TLS using Stubby on OpenWrt 18.06 is remarkably easy. You can use the LuCI web interface to perform these steps or shell command over ssh; I’m providing the commands here.

  1. Refresh the package list: opkg update
  2. Install the stubby package: opkg install stubby
  3. Start stubby: /etc/init.d/stubby start
  4. Set stubby to start automatically at boot: /etc/init.d/stubby enable
  5. Use stubby as the DNS server by editing /etc/config/dhcp
    In the config dnsmasq section, add (or change the values of, if these settings already exist) these settings:

    • option noresolv '1'
    • list server '127.0.0.1#5453'
  6. Restart dnsmasq so the changes take effect: /etc/init.d/dnsmasq restart

If you’d rather use a different DNS over TLS server than Cloudflare’s 1.1.1.1, edit /etc/stubby/stubby.yml.

Now you can restart assured that your DNS queries can’t be seen by 3rd parties.

CC BY-SA 4.0 DNS Over TLS on OpenWrt 18.06 by Craig Andrews is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

19 thoughts on “DNS Over TLS on OpenWrt 18.06

  1. Thanks for the very useful info, Craig.

    I’m not a networking genius, but I’ve successfully installed stubby on several standalone workstations, but when I try to (follow all the instructions here, and) restart dnsmasq, I get:

    udhcpc: started, v1.28.3
    udhcpc: sending discover
    udhcpc: no lease, failing

    … and the router fails to offer any working connections to hosts. Any hints on where I might have gone wrong?

    Thanks again.

  2. If you have stubby,yml correct:

    In /etc/config/dhcp:

    option noresolv ‘1’
    option proxydnssec ‘1’

    The noresolve ‘1’ stops dnsmasq from resolving dns queries from local clients.
    Change t to noresolv ‘0’ to make dns resolving work again.

    The proxydnssec ‘1’ allows dnsmasq to proxy the dnssec from stubby to the clients since stubby only resolves dns internally to the router itself (127.0.0.1).

    Source:
    https://github.com/openwrt/packages/blob/master/net/stubby/files/README.md

    1. Your description of noresolv is incorrect. It stops the use of upstream, DHCP provided DNS servers specified in /etc/resolv.conf – and that’s exactly what we want to do. “option noresolv 1” is correct. See https://openwrt.org/docs/guide-user/base-system/dns_configuration and this is also mentioned in https://github.com/openwrt/packages/blob/master/net/stubby/files/README.md

      Setting proxydnssec ‘1’ is an alternative to having dnsmasq perform dnssec validation which is the approach I recommend. See https://candrews.integralblue.com/2018/08/dnssec-on-openwrt-18-06/

  3. Using this setup Dynamic DNS stops working on the router itself. The issue is drill no longer works on the router:
    Error: error sending query: No (valid) nameservers defined in the resolver
    I’m able to get around this by setting option “noresolve” back to “0”

    Is there a better way to get DDNS working?

  4. @JAMES
    After a reboot I found that DDNS doesn’t work again.

    I’m leaving it with “option noresolv ‘0’” as this is the only way I can get DDNS to work, and since /etc/resolv.conf only contains the loopback address I don’t see how this is an issue anyway.

  5. I’m sorry for all of the posts. But I found the problem. For the router to be able to perform DNS lookups itself you have to follow all of the steps in the section “Disable sending DNS requests to ISP provided DNS servers” in https://github.com/openwrt/packages/blob/master/net/stubby/files/README.md

    tl;dr
    uci set network.wan.peerdns=’0′
    uci set network.wan.dns=’127.0.0.1′
    uci set network.wan6.peerdns=’0′
    uci set network.wan6.dns=’0::1′
    uci commit && reload_config

    If I do that, I can have “option noresolv ‘1’”, and DDNS works, as the router can use drill to do lookups.

  6. This guide was a HUGE help! THANK YOU. I recently installed OpenWRT on my Linksys AC2600 and had no luck following the directions of many other articles explaining how to set cloudflare as the DNS. My networking skills are not very sophisticated, but a few google searches on SSH commands and this article did the trick. Thanks again!
  7. I found that Stubby didn’t start working for a couple of minutes after boot until the kernel eventually outputs “random: crng init done”.

    I installed the haveged package which speeds up the crng init, and then Stubby is working after a couple of seconds.

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