[dnsdist] dnsdist using loopback address as source address for queries

[Adam Bishop]

On 29 Oct 2021, at 13:38, Remi Gacogne via dnsdist <dnsdist at mailman.powerdns.com> wrote:
> Would you mind checking that you still have IPv6 addresses on that interface? I see you still have some on the incoming interface, though, since we receive a query over IPv6 on file descriptor 18 in your strace output.

Yeah, it's a single interface system so the ingress/egress addresses are the same.

> Any events in the system logs that looks like the IP addresses might have changed at some point?

The only thing in dmesg is an SElinux policy update triggered by dnf, but no AVC entries that would indicate that being the cause. NetworkManager hasn't written anything to its own log since boot, which is normal.

> Anything in the dnsdist logs looking like a reconnect (error while writing to the backend, ..)? We should not reconnect unless send() failed with EINVAL or ENODEV, which is not supposed to happen in your case since you don't set the source interface.

There's some normal terminations when the backend is reloaded for config changes, e.g.

  dnsdist[1351]: Timeout while waiting for the health check response from backend [2001:630:1:170::67]:53
  dnsdist[1351]: Marking downstream [2001:630:1:170::67]:53 as 'down'
  dnsdist[1351]: Timeout while waiting for the health check response from backend 193.63.72.67:53
  dnsdist[1351]: Marking downstream 193.63.72.67:53 as 'down'
  dnsdist[1351]: Marking downstream [2001:630:1:170::67]:53 as 'up'
  dnsdist[1351]: Marking downstream 193.63.72.67:53 as 'up'

But that's it - the only other messages are "Packet from:"

Adam

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