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DNSSEC on OpenWrt 18.06

DNSSEC ensures that the results of DNS queries (for DNSSEC enabled domains) are authentic. For example, integralblue.com uses DNSSEC, so if an attacker (using a man in the middle or spoofing attack) changes the IP address that www.integralblue.com resolves to, then a DNS resolver supporting DNSSEC will be able to tell and return an error.

DNSSEC provides authentication and integrity; it does not provide for confidentiality. For confidentiality (so your ISP, for example, cannot tell what DNS queries are being made), you can easily add TLS over DNS which I’ve described how to do in OpenWrt in another post.

By setting up DNSSEC 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 do DNSSEC checking for all queries.

Setting up DNSSEC 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. Swap dnsmasq for dnsmasq-full (-full includes DNSSEC support): opkg install dnsmasq-full --download-only && opkg remove dnsmasq && opkg install dnsmasq-full --cache . && rm *.ipk
  3. Edit /etc/config/dhcp
    In the config dnsmasq section, add (or change the values of, if these settings already exist) these settings:

    • option dnssec '1'
    • option dnsseccheckunsigned '1'
  4. Restart dnsmasq so the changes take effect: /etc/init.d/dnsmasq restart

Enjoy knowing that now no one is tampering with your DNS queries.

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

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  1. Csaba Keleti
    October 23rd, 2018 at 07:50 | #1
    Dear Andrews!

    Sorry, my english is bad, but I have 1 question.

    Doing as writed, after the dnsmasq swap my opkg said, that it created a new /etc/config/dhcp-opkg configuration file, so I think it is the valid configuration file, after the swap.

    +1 question: Does my isp dns require any dnssec support?

    Thanks!

    • October 30th, 2018 at 14:29 | #2
      Your ISP doesn’t care about dnssec; it can’t require or not require it.

      You should always use dnssec as it ensures that the results of DNS queries (for DNSSEC enabled domains) are authentic.

  2. TDFKAOlli
    November 14th, 2018 at 13:32 | #3
    Tried it on OpwnWRT 18.06.1 but unfortunately it has a drawback. I noticed that my DHCP leases used to assign specific IP address to specific MAC adresses fail to work after some time (I think after first lease timeout). Those devices don’t get the set IP address anymore but instead an address from the free range I defined (*.100 to *.180). As I need specific devices to have specific IP addresses I had to remove the package again and go back to dnsmask. Now everything works again.
    • November 28th, 2018 at 13:47 | #4
      I don’t see how the steps involved in this post could cause that change in behavior. Are you sure you haven’t also done something else?
  1. August 10th, 2018 at 11:47 | #1