Publish secondary DNS IP Address - dhcp-option=6

[milothomas]

When using AdGuard as DHCP server, only the primary DNS server address is published. This causes some OnePlus devices to automatically use 8.8.8.8 as the secondary DNS server.

Can we have an option to publish the same IP address for both primary and secondary DNS server addresses?

[Sennevds]

I have the same problem! No my dns rewrites don't work for my cellphone which is quiet annoying.

[temporallyaccount]

@ameshkov can you check this #1822 (comment)
above @milothomas said problem happen on other brands too so.

[dmshimself]

I'd definitely like to see this, plus being able to set the domain name

[ainar-g]

Hi! We've recently pushed a patch for this. Could you please update to the latest development snapshot and check if that fixes the 8.8.8.8 issue?

[Sennevds]

I've just updated to the latest docker(edge) and the 8.8.8.8 address is gone!

[ameshkov]

Awesome, thanks for checking it!

[ainar-g]

We'll close this issue for now. @milothomas, please feel free to reopen with more details if the development version doesn't fix it for you.

[loll31]

hey, i tried last docker images (latest and edge) for testing dhcp 6 option and behavior seems to be incorrect.
if option "- 6 ip addrip" is added, client received only 1 dns server IP and it's the one defined by option.
So i lost adguardhome dns if i used 'option 6'.
My goal is to manage 2 PIs providing adguardhome services at the same time. For surety, the two IP must be announced by DHCP services...

[ainar-g]

@loll31, hi and thank you for your message. There seems to be a misunderstanding or, perhaps, a documentation issue here. In this issue we fixed the logic of sending AdGuardHome's own IP addresses when users don't specify their own servers with option 6. Currently, options set by users silently override the ones set by AdGuardHome automatically, so if you set only one DNS server with option 6 then the DHCP clients will only receive the one address.

Maybe we need to print a warning, on the info level, when users' options override the automatic ones? Perhaps, another warning when the users only provide one DNS server address? Or just automatically double it? Or both? Or just document the whole thing in a separate wiki article?

@ameshkov, what do you think? I personally favour the wiki approach.

[ameshkov]

@ainar-g users can specify multiple DNS servers using option 6, right?

If so, we should just explain that in the Wiki that if this option is set, you'll need to specify AGH address explicitly.

[loll31]

@ainar-g , @ameshkov , thanks for the feedback. i tryed to set 2 IP via option ( - 6 ip ip1,ip2 or - 6 ip ip1 ip2 , w/ or w/o quotes, -6 text "ip1,ip2" or - 6 '''ip','ip'" ...) in vain.
For my comprehension, if option 6 is set, the AGH IP is not used as DNS and users could define 1 or 2 DNS (or more, i dont know if bootp/dhcp norm accepts it) . To resolve the problem OnePlus, maybe AGH should duplicate same IP if only one address is set in config file...

[ainar-g]

@ameshkov, @loll31, it seems that AdGuardHome currently cannot parse two IPs there. Or rather, it can only do it if you use the hex form. So, there are at least two issues here:

1. AdGuardHome cannot parse multiple IPs in DHCP options. This is now DHCP options with multiple IPs #2385.
2. Our DHCP documentation is a bit lacking. This is now Wiki page about running AGH as a DHCP server #2386.

[loll31]

Do you have the syntax for hex form ?
ex: 192.168.1.1 and 192.168.1.2 two DNS servers should be (or a separator should be added ?)

• 6 hex 0xC0A80101C0A80102

[ainar-g]

@loll31, try this:

6 hex c0a80101c0a80102

[loll31]

@ainar-g client sets both ip addresses ! +1
options:
- 6 hex c0a80101c0a80102

Nice !
It's working OOTB !

[loll31]

Maybe not the right place but i try to add option 252 for proxy information. I use
options:
- 252 text "http://192.168.1.1/wpad.dat"
But it seems that it's not sent to client...
Can you confirmed that this is managed by ADH dhcpd ?

[ainar-g]

@loll31, definitely not the right place to ask. Please write a new issue. We'll label it as a question and respond when we have the time.

[loll31]

ok. See you