Re: Mac APP DNS Search Domain

[Sven Auhagen <sven.auhagen@voleatech.de>]

On Mon, Aug 09, 2021 at 09:12:05AM -0700, Stephen Larew wrote:
> On Jul 17, 2021, at 03:09, Sven Auhagen <sven.auhagen@voleatech.de> wrote:
> >
> > Hi,
> >
> > the DNS search domain in the Wireguard Mac APP does not seem to work properly.
> > The search domain is added properly and I can see it in the DNS configuration
> > for the scoped query:
> >
> > resolver #2
> > search domain[0] : mytestdomain.com
> > nameserver[0] : 192.168.6.1
> > if_index : 17 (utun4)
> > flags    : Scoped, Request A records
> > reach    : 0x00000002 (Reachable)
> >
> > but the global resolver is using a mix of my LAN and Wireguard DNS resolver:
> >
> > resolver #1
> > search domain[0] : sven.lan
> > nameserver[0] : 192.168.6.1
> > if_index : 17 (utun4)
> > flags    : Supplemental, Request A records
> > reach    : 0x00000002 (Reachable)
> > order    : 102200
> >
> > I found a discussion on Github about the issue here:
> > https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Ftailscale%2Ftailscale%2Fissues%2F101%23issuecomment-639286398&amp;data=04%7C01%7Csven.auhagen%40voleatech.de%7Cc036b74b5f804c3ae41708d95b50700e%7Cb82a99f679814a7295344d35298f847b%7C0%7C1%7C637641223312894873%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=m59kt6gpqykdVvvyUX4%2BEbF14sCZWfmrZNWEKNzXj3E%3D&amp;reserved=0
> >
> > suggesting that the following will fix it:
> >
> > --- a/Sources/WireGuardKit/PacketTunnelSettingsGenerator.swift
> > +++ b/Sources/WireGuardKit/PacketTunnelSettingsGenerator.swift
> > @@ -88,7 +88,7 @@ class PacketTunnelSettingsGenerator {
> >             let dnsSettings = NEDNSSettings(servers: dnsServerStrings)
> >             dnsSettings.searchDomains = tunnelConfiguration.interface.dnsSearch
> >             if !tunnelConfiguration.interface.dns.isEmpty {
> > -                dnsSettings.matchDomains = [""] // All DNS queries must first go through the tunnel's DNS
> > +                dnsSettings.matchDomains = [""] + dnsSettings.searchDomains // All DNS queries must first go through the tunnel's DNS
> >             }
> >             networkSettings.dnsSettings = dnsSettings
> >         }
> >
> > I do not have an Apple Developer Account so I am not able to compile the code and test it.
> > Can anyone take a look as this would be a great help.
> >
> > Best
> > Sven
>
> Sven,
>
> I have a patch for Wireguard Mac app that enables proper split DNS support. It works well in my usage.  I should properly submit the patch for review by Wireguard folks.  Until then, you can get the patch here:
>
> https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fslarew%2Fwireguard-apple%2Fcommit%2F6ebc356d9e11ab91443e06de5e89f1af57fcdff8&amp;data=04%7C01%7Csven.auhagen%40voleatech.de%7Cc036b74b5f804c3ae41708d95b50700e%7Cb82a99f679814a7295344d35298f847b%7C0%7C1%7C637641223312894873%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=dd9MYi3CkgveF%2BcBAU1sk857lDeLmX2SpMcRy7tL9nM%3D&amp;reserved=0
>
> > Enable "split DNS" configurations for an interface
> >
> > By adding a tilde prefix to a domain name entry in the DNS= line, the
> > domain is interpreted as a "matching domain" for DNS routing instead of
> > a "search domain."  This corresponds to setting a non-empty
> > NEDNSSettings.matchDomains property for the network tunnel.  Using tilde
> > as a prefix is borrowed from systemd-resolved's equivalent usage.
> >
> > If one or more match domains are specified, then the specified DNS
> > resolvers are only used for those matching domains instead of acting as
> > the first resolver before the system's primary DNS resolvers.

Thanks Stephen.
It would be great if you can upstream the patch.
The current behaviour is a problem for non technical users that rely on the short dns names.

Best
Sven

>
> -Stephen

Beste Grüße/Best regards

Sven Auhagen
Dipl. Math. oec., M.Sc.
Voleatech GmbH
HRB: B 754643
USTID: DE303643180
Grathwohlstr. 5
72762 Reutlingen
Tel: +49 7121539550
Fax: +49 71215395599
E-Mail: sven.auhagen@voleatech.de
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