Another systemd-resolved problem in 17.04

[Chris Green]

On Thu, Jun 22, 2017 at 08:41:16AM +1000, Karl Auer wrote:
> On Wed, 2017-06-21 at 18:07 -0400, Tom H wrote:
> > Jun 21 09:54:38 t470 systemd-resolved[961]: Using DNS server
> > > fe80::1e74:dff:fe9d:5b1c%3 for transaction 37661.
> > resolved is querying the wrong server because "fe80::..." is an ipv6
> > link-local address.
> 
> Maybe, but not necessarily. In small networks the local DNS server is
> often on the same link. Of course, if it is not listening on all
> addresses it may not respond when queried on that address. It's not
> clear (to me, but I'm not that familiar with systemd messages) whether
> that "REFUSED" is a DNS failure or a failure to reach the server. That
> is, was it that the DNS server heard the query and refused to answer,
> or was the connection refused?
> 
> You should be able to do this to find out:
> 
>    dig daisy.ubuntu.com @fe80::1e74:dff:fe9d:5b1c%3
> 
> This is what I get when I use my local nameserver's link local address,
> actual address truncated:
> 
> kauer at kt:~$ dig +short daisy.ubuntu.com @fe80::xxxx%wlan0
> 162.213.33.133
> 162.213.33.164
> 
> If the nameserver is listening, but refusing to serve you, you'll get a
> response with a REFUSED status. Don't use "+short" or you won't see it:
> 
> kauer at kt:~$ dig daisy.ubuntu.com @dns1.ethz.ch
> [...]
> ;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 33381
> ;; flags: qr rd ra; QUERY: 0, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
> [...]
> 
Yes, exactly what I get:-

    root at t470:/var/log# dig daisy.ubuntu.com @fe80::1e74:dff:fe9d:5b1c%3

    ; <<>> DiG 9.10.3-P4-Ubuntu <<>> daisy.ubuntu.com
    @fe80::1e74:dff:fe9d:5b1c%3
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 7839
    ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

    ;; QUESTION SECTION:
    ;daisy.ubuntu.com.              IN      A

    ;; Query time: 10 msec
    ;; SERVER: fe80::1e74:dff:fe9d:5b1c%3#53(fe80::1e74:dff:fe9d:5b1c%3)
    ;; WHEN: Thu Jun 22 08:53:34 BST 2017
    ;; MSG SIZE  rcvd: 34


-- 
Chris Green