Make autohost TLDs configurable

[ainar-g]

Context.

Currently, our autohost feature uses the .lan TLD, but there isn't really a consensus on what TLD is the best for such situations. So, we probably need to make it configurable.

[alexpovel]

This would be a fantastic feature. Would like this a lot. Glad I found this issue.

As far as "no consensus" goes, I had read this thread. Now I'd like to go the home.mydomain.com (or similar) route. .lan works fine for now, but as mentioned in those threads, it's not safe until we have proper reserved TLDs for home/private/internal use (.lan is currently nothing official AFAIK: not a global TLD but also not explicitly reserved for internal use).

The cool thing about using a FQDN you own is that you can get certificates for private use, via Let's Encrypt's DNS challenge, for example using Caddy. This works without the requesting machine having to be publicly accessible. In theory, this would upgrade the home network quite a bit and stop browsers from throwing tantrums about untrusted local HTTPS, or unsecured HTTP sites.

Could this feature become a YAML config option? Would prefer that over a GUI approach.

Are these the relevant two lines with .lan?

AdGuardHome/internal/dnsforward/dns.go

Lines 169 to 172 in 9f75725

	if !strings.HasSuffix(host, ".lan.") {
	return resultDone
	}
	host = strings.TrimSuffix(host, ".lan.")

If this were Python, I'd have a crack at it...

[ainar-g]

@alexpovel, yeah that's the piece. You could try, but be aware that PRs are unfortunately taking a lot of time to get reviewed right now, and the code is also a bit… macaroney with the configuration.

[Lenart12]

Changing dhcp option in the config files under dhcp->dhcpv4->options by setting - 15 hex 6c616e (setting dhcp domain name to lan) seems to make local rewrites like host1.lan work, however it would still be nice if we could change that via gui or in the configs to something other than lan.

[alexpovel]

@Lenart12 , .lan is the current, hard-coded default, so it should definitely work, see also this earlier comment. It also works without doing anything.

The interesting part would be if other values work, or what it says in

cat /var/lib/dhcp/dhclient.*leases

on one of your machines that received a DHCP lease with that - 15 hex 6c616e option set. In my network, it doesn't mention lan anywhere, because I haven't set that option - so all as expected. Does it show a value there for you? That would make things different.

[ainar-g]

This is implemented as of snapshot 3764c1d. The Wiki is also updated. Please feel free to file new issues if you have any problems!