DoT support with client ID

[orangetech]

According to Adguard wiki https://github.com/AdguardTeam/AdGuardHome/wiki/Clients#clientid, the users client ID can be set based on the url used for DoT.

I'm trying to connect to my adguard instance with clientID.adguard.example.com but there is a certificate mismatch because *.adguard.example.com certificates aren't being generated. See the error message below:

dog google.com --tls @clientid.adguard.example.com
Error [tls]: error:1416F086:SSL routines:tls_process_server_certificate:certificate verify failed:../ssl/statem/statem_clnt.c:1914: (Hostname mismatch)

The main reason I want to do this is to limit DNS requests to certain clientIDs so I can use the private dns function on android. I can't use my cell IP address because it's dynamic, so that is the only way I see to have a locked down DNS server. I believe all that needs to be done is to issue certs for the adguard instance (as is already done) and then a wildcard cert for *.adguard.example.com.

[robi]

There are apps like DNS66 and others that can set your DNS server explicitly (root) or implicitly via VPN to lock down DNS requests.

Check on Fdroid.

[girish]

From what I could make out from the AdGuard home config, only one TLS cert can be provided. This means that the cert for *.adguard.example.com and adguard.example.com need to be combined into one cert. We have to add support for such a cert in Cloudron since we don't request combined certs.

[girish]

It could also be that in ClientID mode, DoH with adguard.example.com is not supposed to work. Only client.adguard.example.com is supposed to work.

In any case, apart from the certs, we also need to set up wildcard DNS.

[7dowWilkes]

@girish Hi, I just had the same problem as "orangetech" and the same wish to use the client id as access restriction. What I don't understand:
I use my domain via netcup API and it was created for me by cloudron (probably) a wildcard certificate.
Why can't this wildcard certificate be used for the AdGuard app? When I check the certificate in the AdGuard web interface, it shows me that the certificate used is only valid for the main domain.
It would be nice if the client ID filtering option becomes possible.

[girish]

@7dowWilkes said in DoT support with client ID:

Why can't this wildcard certificate be used for the AdGuard app?

The wildcard cert does not cover the bare domain cert, because of the way certs work. AdGuard also only supports one cert at a time. This means that we have to get a cert which combines the bare domain (foo.com) and the wildcard (*.foo.com). Have to fix Cloudron's tls addon logic to support such an app. It's on my list.

[nichu42]

@girish
Is this supposed to work now?
I installed the latest AdGuard Home version with Cloudron and set a wildcard alias (*.thirdlevel).
But my Android phone is still unable to connect to device.thirdlevel.domain.com

Is there still something that has to be implemented on Cloudron's side or am I missing something?

[girish]

@nichu42 It will only work with next cloudron release - 7.4.

AdGuard supports ClientID in both DoH and DoT.

DoH client id works already right now. You can use this in firefox, for example, like this (in about:config). Screenshot below is from desktop but maybe the mobile client supports it:

Android only supports DoT (the 'private DNS' feature). It requires a change in platform and thus will only work in next release.

[nichu42]

@girish
OK, thanks. I was a bit confused by the AdGuard changelog you posted that said "Add ClientID support with DoT".
So we're not waiting for an AdGuard Home release, but for the next Cloudron release.

[nichu42]

@girish

I just wanted to leave a big thank-you!
DoT works perfectly with Cloudron 7.4, so I can cancel my NextDNS subscription now.

[luckow]

@girish mh. is there anything to do if there is already a previous version of adguard & cloudron? The moment I updated both to the latest version and added an alias for the wildcard certificate, there is a mismatch between sub third and third level domain.

dog cloudron.io --tls @phone.adg.example.org
Error [tls]: error:0A000086:SSL routines:tls_post_process_server_certificate:certificate verify failed:ssl/statem/statem_clnt.c:1889: (hostname mismatch)

dog cloudron.io --tls @adg.example.org
A cloudron.io. 5m00s 165.227.67.76

Forget about this question. I tested it with the wrong instance with v7.3

[7dowWilkes]

@girish
also a big thank you from my side - the solution of software-version and adguard works like a charm

[lukas]

@girish said in DoT support with client ID:

Android only supports DoT (the 'private DNS' feature). It requires a change in platform and thus will only work in next release.

is it already working? Trying to get it running but I have no success

[nichu42]

@lukas said in DoT support with client ID:

is it already working? Trying to get it running but I have no success

Yes, it is. I have DoH and DoT enabled and restricted access to my clients. It's working great.
What have you tried so far? Which Cloudron version are you running?

[lukas]

@nichu42 said in DoT support with client ID:

What have you tried so far? Which Cloudron version are you running?

Added Client ID, like lukas-android to allow list, and added an alias lukas-android.agh.mydomain.tld to AdGuard Cloudron App. I'm running Cloudron 7.4

Regards,
Lukas

[girish]

@lukas let's follow up at https://forum.cloudron.io/topic/9033/adguard-home-wildcard-aliases