CODA-4582U - Custom DNS

[kyle2412e12e]

I have setup Adguard as a service on my Mac and it requires me to put the IP address in my DNS settings. However, when I do this and save, the traffic isn't being routed to the IP.  Am I missing a step? I included a screenshot of where I am entering the Adguard IP address. 

From Adguard:

To start using AdGuard Home, you need to configure your devices to use it.

AdGuard Home DNS server is listening on the addresses.

Where I put the IP adress in my Hitron router settings: 

***Added Labels***

[Datalink]

@kyle2412e12e you have the correct location, but, that's not the AdGuard DNS.  I'm assuming that's the address of your Mac in which case, your DNS definitely wouldn't work as it should.  

Ok, so, there are two ways to do this:

1.  By entering the correct DNS address into the modem location that you indicated; or

2.  By entering the correct DNS address into the correct location in the Mac's operating system.  

The correct IPV4 DNS addresses that you would use in the modem are shown in the following AdGuard page:

https://adguard.com/en/adguard-dns/overview.html

Scroll down and select the router icon on the right hand side.  The DNS addresses are the same no matter what platform you use, but the device icons, when selected, show the procedure to enter the DNS addresses into the indicated devices.   In this case, the router instructions are used for the 4582 modem.  Looking at your image, I see that Rogers and Hitron have still not included the IPV6 DNS addresses for user entry, as was done in the past.  For more on this see below.  For now, use the IPV4 addresses as the entry addresses in the DNS entry windows. 

To use the addresses directly in your Mac, simply select the macOS icon on that page to view the Mac DNS entry procedure.  I'm assuming here that you can use IPV6 with the Mac, in which case you would enter both IPV4 and IPV6 DNS addresses.  

Ok, just to complicate this, the lack of an IPV6 DNS entry capability in the modem would mean that if you were using IPV6, you would still use the Rogers IPV6 DNS instead of the AdGuard IPV4 DNS.  Without any DNS entry, the modem would default to the Rogers IPV6 DNS  which in turn is used by all of the connected devices.  If you switched to the Gateway Function in the modem you would see the Router Mode, which can be set to IPV4, IPV6 or Dual (IPV4 + IPV6).  If you have Dual mode currently selected, meaning that the modem supplies both IPV4 and IPV6 services, IPV6 would be the default address scheme used by the Mac as it appears that Mac OS gives preference to IPV6.  That translates to the Mac using the Rogers IPV6 DNS as the primary DNS source instead of the AdGuard IPV6 DNS.

There are two ways around this:

1.  Set the Router Mode in the modem to IPV4 only and save the changes.  That means that you won't be using IPV6 in any of your devices.  In this case, enter the correct IPV4 AdGuard DNS addresses into the entry windows in your image.  Reboot the router and any connected devices to ensure that the AdGuard DNS is used from that point in time. 

2.  Leave the Router Mode set to Dual, but, enter the IPV6 and IPV4 AdGuard DNS addresses into the Mac's OS.  Reboot the Mac when that is done.  The Mac will use the AdGuard DNS from that point in time.  

Did you download the AdGuard application for the Mac and install it?  I had a quick look at the AdGuard for MacOS support page but didn't see any indication or statement that the installation also changed the DNS addresses in the MacOS.  I'm guessing that leaves the DNS change up to the user??   If so, follow the instructions shown above to enter the IPV4 and possibly the IPV6 AdGuard DNS addresses into the modem and/or the Mac.

Here's the AdGuard for Mac documentation page;

https://kb.adguard.com/en/macos

Please let us know if this works as it's expected to work.   If not, post any questions that you might have.

[kyle2412e12e]

Hi Datalink,

Thanks for your detailed reply, I appreciate the time you took to answer. Note though that I am using a more advanced service called Adguard Home which is different than Adguard DNS as it allows for customization of filters and blocklists: https://github.com/AdguardTeam/AdGuardHome

I have included a screenshot of their setup guide below:

[Datalink]

@kyle2412e12e ok, I see what you're trying to do.  In theory this should be fairly simple.  The question of the day is whether or not the modem firmware will allow a private address IP address for the DNS address?  You would have to use the same address in both entry windows so that only the Mac's IP address is used for the DNS address.  

1.  What happens when you use that same address for both DNS 1 and DNS 2 entries?

2.  Does the modem firmware accept those entries, and, does it actually work?  

I'm wondering at this point if the modem will accept those entries and even if it does, whether or not that forces the modem to use an internal IP address instead of the usual external IP address.  With a router this would be easy to accomplish.  It all depends on how the modem firmware is coded.  

Even if this does work, you still have the issue of the missing IPV6 DNS address entries, which if you're using IPV6, will cause any connected devices to use the external Rogers IPV6 DNS instead of the internal AdGuard IP address.  That will simply allow devices to bypass your attempts to use AdGuard.  

The other issue is the IP address for the Mac.  A modem reboot might result in a totally different IP address for the Mac.  You should create an IP reservation for the Mac so that a modem reboot, whether intentional or not will result in the same IP address being assigned to the Mac after the reboot.  

I don't have any other ideas for this as I'm not aware of what limitations there are, within the firmware, when it comes to the allowed IP addresses for the DNS addresses.  This will either work, or it won't 😞

[kyle2412e12e]

This sucks, apparently repeated IP are not allowed... and I had a router however the modem wouldn't route traffic to it. Something about this modem really restricts customization. 

[Datalink]

@kyle2412e12e consider trying something completely off the wall.  Enter the correct IP address as DNS 1 and then enter a bogus address as DNS 2.  Something like 192.168.200.1, which should be well above the typical address range for the modem.  See if the modem firmware will accept that.  

If it works, that configuration means that you really have just one IP address running for DNS purposes.  I wonder if there would be situations where the first IP address is busy, so the modem directs the DNS address query to the bogus address?  If that happens, you might see slight delays in web page loading for example.  I'm just speculating, but, I can see that happening.  

To run this configuration and ensure that AdGuard is used as the DNS source, you would have to deselect Dual mode as the Router mode in the Gateway Function tab, selecting IPV4 as the Router mode instead. 

[kyle2412e12e]

Your suggestion of turning off dual mode worked. Adguard is receiving traffic now using their DNS address and the dummy one you provided. Given that it is the newest protocol, could we turn on IPv6 instead of IPv4? Why is IPv4 required for this to work?

[Datalink]

Various operating systems will or might choose to run IPV6 first, IPV4 second.  Windows will do that.  Not sure about Macs or Android systems.  I'd bet that they would run IPV6 first as well.  

So, if you were running dual mode, the modem will supply the IPV6 prefix to the connected devices in order to generate the IPV6 IP addresses.  The modem will also supply the default IPV6 DNS address.  In this case, as Rogers has dropped the previous IPV6 DNS user entries from the user interface, leaving the IPV4 entry windows only, the modem will supply the default IPV6 DNS IP address which will be the Rogers IPV6 DNS.  End result, any and all connected devices that run IPV6 first, will use the Rogers IPV6 DNS instead of the AdGuard IPV4 address.  So, your intention of using AdGuard for ad blocking, etc, etc, will be blown away due to the use of the IPV6 DNS address.  

Only two things will solve that situation;

1.  Rogers returns the IPV6 DNS entry windows.  It shouldn't be that hard as all Hitron has to do is to reuse the previous code.  

2.  Run the modem in Bridge mode and use your own router, where you have full control over the DNS addresses used by your network.  

Edit:  just remembered that firmware version 7.x for the CODA-4582 modem is built with an updated kernel.  Its possible that Hitron dropped the ball and didn't carry the IPV6 DNS entries forward into version 7.x  from the previous version.  So the question is, "will the IPV6 DNS entries ever return to the user interface? "