[kwlug-disc] Systemd resolv issue ...

[Khalid Baheyeldin]

Thanks Chris, that is very helpful.

It seems there is a way to do per interface DNS (split DNS) using systemd.

Like this:

cat /etc/systemd/network/wg0.network
[Match]
Name=wg0

[Network]
DNS=10.10.0.1
Domains=priv

Then restart systemd-networkd, then wg-quick

When I do this, resolvectl shows:

Global
        Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported
 resolv.conf mode: stub

Link 3 (enp3s0)
   Current Scopes: DNS
        Protocols: +DefaultRoute -LLMNR -mDNS -DNSOverTLS
DNSSEC=no/unsupported
Current DNS Server: 192.168.0.1
      DNS Servers: 192.168.0.1
       DNS Domain: lan

Link 15 (wg0)
   Current Scopes: none
        Protocols: -DefaultRoute -LLMNR -mDNS -DNSOverTLS
DNSSEC=no/unsupported
      DNS Servers: 10.10.0.1
       DNS Domain: priv

Which shows that 10.10.0.1 will be the DNS server for domain suffix .priv

No idea why DNS Domain is "lan" for the main ethernet connection.

But after doing all that, I cannot ping the 10.10.0.1 gateway, nor does
name lookup work on .priv hosts.

So I went back to your idea of adding PostUp, and completed it with PostDown

It looks like this:

PostUp = resolvectl dns %i 10.10.0.1
PostUp = resolvectl domain %i priv
PostDown = resolvectl revert %i

It seems to work so far.
I can ping and resolve everything (private and global)

Link 3 (enp3s0)
   Current Scopes: DNS
        Protocols: +DefaultRoute -LLMNR -mDNS -DNSOverTLS
DNSSEC=no/unsupported
Current DNS Server: 192.168.0.1
      DNS Servers: 192.168.0.1
       DNS Domain: lan

Link 16 (wg0)
   Current Scopes: DNS
        Protocols: +DefaultRoute -LLMNR -mDNS -DNSOverTLS
DNSSEC=no/unsupported
Current DNS Server: 10.10.0.1
      DNS Servers: 10.10.0.1
       DNS Domain: priv

But there is +DefaultRoute on both interfaces ...

Many thanks Chris.
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