{"id":3959,"date":"2020-11-30T10:00:00","date_gmt":"2020-11-30T16:00:00","guid":{"rendered":"https:\/\/www.foell.org\/justin\/?p=3959"},"modified":"2020-11-30T10:04:52","modified_gmt":"2020-11-30T16:04:52","slug":"dynamic-dns-with-openwrt-19-07-and-nsupdate-info","status":"publish","type":"post","link":"https:\/\/www.foell.org\/justin\/dynamic-dns-with-openwrt-19-07-and-nsupdate-info\/","title":{"rendered":"Dynamic DNS with OpenWrt 19.07 and nsupdate.info"},"content":{"rendered":"\n

I went to resurrect my dynamic DNS configuration on my OpenWrt router<\/a>. The idea was sparked from a reader comment<\/a>, so I wanted to follow-up on using nsupdate.info<\/a> with OpenWrt for a DIY Dynamic DNS setup.<\/p>\n\n\n\n

Before I began, I thought I should see if there’s a newer OpenWrt version my router can run. I always start on the Supported Devices<\/a> page of the wiki, but on this visit I was treated to a warning:<\/p>\n\n\n\n

\"\"<\/a><\/figure>\n\n\n\n

If you read the 4\/32 warning<\/a>, the crux of the matter is that there may not be enough RAM to run OpenWrt without crashing. And the small flash area means possibly not having enough room to install LuCI, the web interface, and the packages to access LuCI via HTTPS<\/a>. Also, there’s this:<\/p>\n\n\n\n

Previous versions of OpenWrt (such as earlier versions of 17.01.x, 15.05.x \u201cChaos Calmer\u201d and prior) contain now-known security vulnerabilities in the kernel, wireless implementation, and\/or application code. […] In many cases, these known vulnerabilities are being actively targeted, potentially including by advanced, likely state-sponsored or state-affiliated actor<\/a> or actors.<\/p><\/blockquote>\n\n\n\n\n\n\n\n

Ugh, I was<\/em> using one of those older versions, and now I’m paranoid (as I should be) that my router could be used as a tool by nation-states to do their bidding. Nicely, there’s a link on the supported devices page titled “I want to buy a router which is supported by OpenWrt.”<\/a> It links to their supported hardware table, pre-filtered by units that can run the latest stable version of OpenWrt – 19.07.4 at time of writing.<\/p>\n\n\n\n

I spent some time browsing this list compared to what was available at my local Micro Center<\/a>. I tried to find one that had the best OpenWrt support with the fewest known issues, and landed on the TP-Link C7 AC1750<\/a> for $70. If I like this one after a month or so, I’m going to buy another for better coverage.<\/p>\n\n\n\n

OpenWrt ddns-scripts install<\/h2>\n\n\n\n

With the hardware choice out of the way, I installed OpenWrt 19.07.4. Then I needed to add support for Dynamic DNS<\/a>. Go to System -> Software<\/em> in the Web UI (LuCI). Click Update lists…<\/em>, then type ddns<\/code> in the filter input and press <Enter> to filter the list. The packages to install to use nsupdate.info are ddns-scripts_nsupdate<\/code> and luci-i18n-ddns-en<\/code> (or whatever language package you need):<\/p>\n\n\n\n

\"\"<\/a><\/figure>\n\n\n\n

Installing those will also install their dependencies, such as the base ddns-scripts<\/code> and luci-app-ddns<\/code>. Once they’re installed, reboot your router and you’ll have a Services -> Dynamic DNS<\/em> menu.<\/p>\n\n\n\n

You might see the menu before rebooting, but you’ll likely get this error if you try to visit it:<\/p>\n\n\n\n

\/usr\/lib\/lua\/luci\/controller\/ddns.lua:116: attempt to index field '?' (a nil value)<\/code><\/pre>\n\n\n\n
Rebooting should take care of it.<\/a> Then on the new Dynamic DNS<\/em> page, you may see a Hints<\/em> notification like this:<\/p>\n\n\n\n
\"\"<\/a><\/figure>\n\n\n\n
Following it will lead you to a hints page and let you know you need to install a couple more packages: curl<\/code> and bind-host<\/code>. Follow the same installation process as above. After they’re installed, the Hints<\/em> section will go away.<\/p>\n\n\n\n
DNS Configuration<\/h2>\n\n\n\n
The only configuration you have to do at your DNS provider is add a CNAME<\/code> record for the domain you want to use:<\/p>\n\n\n\n
your.domain.com CNAME yourdomain.nsupdate.info<\/code><\/pre>\n\n\n\n
Then when you go to nsupdate.info, on the Overview<\/em> page click Add Host<\/em> and put in the subdomain (example: yourdomain<\/code> from above) in the Name<\/em> field, then select nsupdate.info<\/code> under Domain<\/em>:<\/p>\n\n\n\n
\"\"<\/a><\/figure>\n\n\n\n
Conveniently, after creating your new host entry, nsupdate.info will print your update secret and include specific configuration parameters for OpenWrt:<\/p>\n\n\n\n
\"\"<\/a><\/figure>\n\n\n\n
OpenWrt Configuration<\/h2>\n\n\n\n
You can use the configuration info from nsupdate.info, but it’s just as easy to paste the info into the LuCI panel. It’s worth noting that you only need to generate one host and host secret at nsupdate.info, but you’ll have two separate configurations in OpenWrt for IPv4 and IPv6.<\/p>\n\n\n\n
In OpenWrt’s Dynamic DNS<\/em> page, click Edit<\/em> on the myddns_ipv4<\/code> row. The first thing you’ll want to do is update the DDNS Service provider<\/em> to nsupdate.info<\/code> and click Change provider<\/em>:<\/p>\n\n\n\n
\"\"<\/a><\/figure>\n\n\n\n
Only then can you enter all of the information from nsupdate.info:<\/p>\n\n\n\n
\"\"<\/a><\/figure>\n\n\n\n
Enter your nsupdate.info FQDN<\/a> in all of these fields:<\/p>\n\n\n\n