Category: Network

Cloudflare Managed DNS

Consider this an update to a previous article where I talk about using rebel.ca to manage my DNS records. I still like them as a company, and the support is generally good – I will no longer recommend them. Without getting into the details, I had a DNS management problem with them that was the last straw for me, this resulted in about 36hrs of downtime for this domain.

The good news is that today, there are lots of free managed DNS providers. Really this isn’t a huge technical challenge. You need two nameserver entries in your SOA that is managed by your registrar. Ideally those nameservers are hosted on machines that are on different networks and in different locations for good redundancy. As far as management of the record, having a friendly web UI isn’t a huge problem in 2024. These servers will answer DNS requests for the many DNS servers out there that ask for a name to IP mapping.  Yes, there are real costs to operating one of these – but for an individual personal domain, the number of queries and amount of data is pretty tiny.

I decided to go for Cloudflare, they offer a generous free plan and are pretty central to the operation of the internet as a whole. Hopefully I can trust them to manage my DNS record(s), but I do have some reluctance because the internet is dominated by a few huge tech companies which isn’t great. I believe the internet needs to be built on open standards and we need lots of medium sized companies providing services.

You can sign up for Cloudflare in minutes. Entirely self service, and email confirmation is used to give you full access.

Adding one of my domains to be managed by Cloudflare is easy. I want to click on the ‘Website’ entry on the left navigation bar. Then I pick +Add a site to enter the domain I want them to manage DNS for.

Now we pick the ‘Free’ plan and move to the next step.

Cloudflare does a pretty slick job of sniffing out your existing DNS records (assuming you have some) and populating it’s configuration. Review these and edit as needed. Then we can continue.

As I mentioned above, I really don’t want Cloudflare messing with things much – so I disabled the “Proxy” for all of my records and have it setup as DNS only. If I ever have a problem, I can go in and use some of their free DDoS protection stuff – but let’s start with just the basics.

To enable Cloudflare to be my DNS provider, I need to go change the record with my domain registrar so that it points at the Cloudflare name servers. Cloudflare monitors this and will make my domain ‘active’ in the dashboard, but they’ve already created the DNS records and things are good to go. It was a matter of minutes for my domain to become active once I’d modified the SOA with my registrar.

I did this back a few weeks ago. So far so good, but then again DNS is pretty boring when it’s not breaking the internet.

 

OpenWRT on GL.iNet GL-MT6000 (aka: Flint 2)

I was reading through the OpenWRT forum several months back to see if the TPLink AX23 was still the right upgrade choice for me. I’ve been very happy with the classic TPlink Archer C7 – having 3 of these as my core network (two as dumb AP). I came across this thread on devices for ‘newcomers’ and discovered the GL.iNet GL-MT6000, it looks like a monster bit of hardware at a pretty low price point. My travel router is a GL.iNet device and it’s been great hardware for OpenWRT. Then bonus time at work hit, and I ran out of excuses to buy the GL-MT6000.

While you can buy directly from GL.iNet, just after I pushed the buy now button there I discovered that I was going to be on the hook for import duties and the shipping was via FedEx. I’ve not had good experiences with this path and the administration fees are high. The support process from GL.iNet was amazing – a few emails and my order was cancelled without any fuss.

I ended up buying via Amazon.ca (camelcamelcamel link) because shipping costs were predictable. I see that it’s not currently in stock, but my total including shipping was $248.49 – still a deal for this much hardware.

Speaking of hardware

  • Two 2.5Gb ports
  • 1GB RAM
  • 8GB Flash
  • Quad core 2GHz CPU
  • Wifi6

This may not be enough hardware to handle 1Gb symmetric fibre, but I’m still back on a much slower cable 100/30 plan. It also gets me thinking about upgrading my network switches to 2.5Gb.. but that’s a different post.

The device itself has some heft to it – there is apparently a sizeable heat-sink inside. The power cord is short – about 3′, and there is no power switch, not a problem for me, but I can see why some people felt this was a limitation.

Of course, the very first thing I’m going to do is flash this with OpenWRT. This is as simple as grabbing the sysupgrade.bin file from https://openwrt.org/toh/gl.inet/gl-mt6000 and connecting to the device over a wired connection.

The factory firmware hosts an administration web UI on http://192.168.8.1/ allowing you to do basic setup. I’m prompted to pick a language and set a password.

From this screen we can select Upgrade on the left navigation bar, then local upgrade and upload the sysupgrade.bin file we downloaded

The built in firmware handles the upgrade very nicely, it even detects a kernel change and automatically selects to not keep setting (which is what the OpenWRT wiki advises)

Even during the upgrade the web UI is pretty slick

Once it hits 100% it will automatically reboot. Since the OpenWRT default IP is different, we need to visit a different admin web page http://192.168.1.1

I have to say that the exterior of the device has a matte black finish, and the angular styling appeals deeply to my 80’s stealth bomber admiring inner teen. It reminds me of the USRobotics Courier 56k modems back in the day.

At this point we’ve got OpenWRT installed, and it’s just a matter of working through the configuration steps. I did run into a few problems that were my own tripping over my own feet issues. Linux apparently ‘remembers’ the name of the connection, and the type of connection security. If you change the encryption but not the name it seems you can run into problems. I also messed up one of the passwords with a type-o. Eventually I got it all settled down and things worked great.

PSA: DNS servers have no priority order

It is a common misconception that DNS servers that your system uses are managed in a priority order. I had this misunderstanding for years, and I’ve seen many others with the same.

The problem comes from the router or OS setup where you can list a “Primary” and “Secondary” DNS server. This certainly gives you the impression that you have one that is ‘mostly used’ and a ‘backup one’ that is used if the first one is broken, or too slow. This is false, but confusingly also sometimes true.

Consider this stack exchange question/answer. Or this serverfault question.  If you go searching there are many more questions on this topic.

Neither DNS resolver lists nor NS record sets are intrinsically ordered, so there is no “primary”. Clients are free to query whichever one they want in whichever order they want. For resolvers specifically, clients might default to using the servers in the same order as they were given to the client, but, as you’ve discovered, they also might not.

Let me also assure you from my personal experience, there is no guarantee of order. Some systems will always try the “Primary” first, then fall back to the “Secondary”. Others will round-robin queries. Some will detect a single failure and re-order the two servers for all future queries. Some devices (Amazon Fire Tablets) will magically use a hard coded DNS server if the configured ones are not working.

Things get even more confusing to understand because there is the behaviour of the individual clients (like your laptop or phone), and then the layers of DNS servers between you and the authoritative server. DNS is a core part of how the internet works, and there is lots of information on the different parts of DNS out there.

The naming “Primary” and “Secondary” come from the server side of DNS. When you are hosting a system and configure the domain name to IP mapping, you set up your DNS records in the “Primary” system. The “Secondary” system is usually an automated replica of that “Primary”. This really has nothing to do with what the client devices are going to do with those addresses.

Another pit-fall people run into when they think there is an ordering, is when they setup a pi-hole for ad-blocking. They will use their new pi-hole installation as the “Primary” and then use a popular public DNS server (like 8.8.8.8) as the “Secondary”.  This configuration sort of works – at least some of the time, your client machine will hit your pi-hole and ad-blocking will work. Then, unpredictably it will not block an ad – because the client has used the “Secondary”.

Advice: Assume all DNS servers are the same and will return the same answer. There is no ordering.

I personally run two pi-hole installations. My “Primary” handles about 80% of the traffic, and the “Secondary” about 20%. This isn’t because 20% of the time my “Primary” is unavailable or too slow, but simply that about 20% of the client requests are deciding to use the “Secondary” for whatever reason (and that a large amount of my traffic comes from my Ubuntu server machine). Looking deeper at the two pi-hole dashboards, the mix of clients looks about the same, but the “Secondary” has fewer clients – it does seem fairly random.

If your ISP hands out IPv6 addresses, you may find that things get even more interesting as you’ll also have clients assigned an IPv6 DNS address, this adds yet another interface to the client device and another potential DNS server (or two) that may be used for name lookups.

Remember, it’s always DNS.