[sane-devel] network scanning quit working

[Perry Hutchison]

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.

Details:

  Canon ImageCLASS MF4880dw


  Ubuntu 18.04.5 LTS
  Intel processor, 64-bit mode

  $ scanimage -V
  scanimage (sane-backends) 1.0.27; backend version 1.0.27

  $ scanimage -L
  No scanners were identified ...

  $ ping 169.254.53.67
  PING 169.254.53.67 (169.254.53.67) 56(84) bytes of data.
  64 bytes from 169.254.53.67: icmp_seq=1 ttl=1 time=0.707 ms
  64 bytes from 169.254.53.67: icmp_seq=2 ttl=1 time=0.452 ms
  64 bytes from 169.254.53.67: icmp_seq=3 ttl=1 time=0.397 ms
  ^C
  --- 169.254.53.67 ping statistics ---
  3 packets transmitted, 3 received, 0% packet loss, time 2049ms
  rtt min/avg/max/mdev = 0.397/0.518/0.707/0.137 ms

  $ traceroute 169.254.53.67
  traceroute to 169.254.53.67 (169.254.53.67), 64 hops max
    1   169.254.53.67  0.799ms  0.639ms  0.470ms

None of these interventions made any difference:
  Adding the scanner's new IP address to /etc/sane.d/net.conf
  Setting SANE_NET_HOSTS to the scanner's new IP address
  Running scanimage -L as root

What other configuration hacks should I try?  (I'd rather not
go to the trouble of upgrading, and would not expect to need
to since this same scanner was working previously with the
1.0.27 release.)