[sane-devel] network scanning quit working

[Perry Hutchison]

Ralph Little <skelband at gmail.com> wrote:

> Hi,
>
> On 2020-12-03 4:48 p.m., Perry Hutchison wrote:
> > This has to be something utterly trivial :(
> >
> > I have a Canon copier/printer/scanner on the same (wired) Ethernet
> > as an Ubuntu Linux system.  In the past this combination has "just
> > worked" -- I didn't have to configure anything -- but today neither
> > Simple Scan nor "scanimage -L" can find the scanner.
> >
> > The one change I know of is that, since the last time it was working,
> > the scanner reported (via the front-panel LCD) that its IP address
> > had changed; and the new IP address is a bit strange:  169.254.53.67,
> > (previously 192.168.0.10, the local network being 192.168.0/24).
> > Since it was found automatically before, and it does respond to ping
> > at its new address, I would expect it to be found again despite the
> > changed IP address.
> >
> Sounds to me like the printer is on a different subnet, so it would be
> unlikely to be found automatically.

Nor, apparently, by adding its IP address to /etc/sane.d/net.conf or
setting SANE_NET_HOSTS.  That's why it had occurred to me to inquire
whether there might be other "where to find the networked scanner"
settings.

> Do you know why the printer has acquired an IP address that is not
> on the same subnet as your Linux machine?

I know "how" it happened, but not "why."

There was a power outage a while back, and after power came back on
I noticed the "changed IP address" message on the scanner's LCD --
but I didn't notice that the new address was on a strange subnet
until today (after discovering that the scanner wasn't being found).

Interestingly, despite its being addressed on the wrong subnet, ping
and traceroute still find it -- and (per traceroute) it does not take
an extra hop (e.g. via the router) to reach it.

> If the scanner setup for DHCP?

I thought it was; it even has a reserved IP address (192.168.0.10) in
the DHCP server (Netgear router).

> Cheers,
> Ralph