[sane-devel] Net Client Not Contacting Server

C. Cook c.a.cook at quantum-sci.com
Wed Sep 9 16:38:57 BST 2020

On 2020-09-09 07:31, Ralph Little wrote:
> Hi,
> On 2020-09-06 8:11 a.m., C. Cook wrote:
>> On 2020-09-05 22:57, Olaf Meeuwissen wrote:
>>>>> In dll.d there is iscan which contains:
>>>>> epkowa
>>>>> net
>>> This is on the server, right?  Because its the server that communicates
>>> with the device via the epkowa backend.
>> This is on the server.  So maybe I don't even need net on the server.
> That's correct, you don't need the net backend on the server side.
> I feel that the net/saned setup is not well documented in general and
> many people have problems setting this up.
> In fairness, a lot of the problems that people experience are related to
> the vagaries of networking, often to do with firewalls and such like.
> The net backend is for the client and it talks to to saned. Saned runs
> on the server and talks to your non-networked hardware, and acts as your
> proxy.
> First things first, we should make sure that the net client is trying to
> dial out to saned, as you state that you cannot see port 6566 traffic there.
> As Olaf suggests., could you try
> SANE_DEBUG_NET=128 scanimage -L
> ...on the client and capture the output and post it here?
> At least we should be able to see what the net backend is up to.
> Cheers,
> Ralph

Whew, thank you Ralph.  As the server is in effect the proxy, it seems I
need only install the Epson iScan software there.  But then it seems
that there is also be a client component to it, so I've also installed
it on the client. 

I did as Olaf suggested and "Name or service not known", which doesn't
make sense:

# SANE_DEBUG_NET=128 scanimage -L
[sanei_debug] Setting debug level of net to 128.
[net] sane_init: authorize != null, version_code != null
[net] sane_init: SANE net backend version 1.0.14 (AF-indep+IPv6) from
sane-backends 1.0.27
[net] sane_init: Client has little endian byte order
[net] sane_init: searching for config file
[net] sane_init: connect timeout set to 30 seconds
[net] sane_init: trying to add scan-server
[net] add_device: adding backend scan-server
[net] add_device: error while getting address of host scan-server: Name
or service not known
[net] sane_init: trying to add localhost
[net] add_device: adding backend localhost
[net] add_device: backend localhost added
[net] sane_init: done reading config
[net] sane_init: evaluating environment variable SANE_NET_HOSTS
[net] sane_init: evaluating environment variable SANE_NET_TIMEOUT
[net] sane_init: done
[net] sane_get_devices: local_only = 0
[net] connect_dev: trying to connect to localhost
[net] connect_dev: [0] connection succeeded (IPv4)
[net] connect_dev: sanei_w_init
[net] connect_dev: net_init (user=carl, local version=1.0.3)
[net] connect_dev: freeing init reply (status=Success, remote version=1.0.3)
[net] connect_dev: done
[net] sane_get_devices: finished (0 devices)

No scanners were identified. If you were expecting something different,
check that the scanner is plugged in, turned on and detected by the
sane-find-scanner tool (if appropriate). Please read the documentation
which came with this software (README, FAQ, manpages).
[net] sane_exit: exiting
[net] sane_exit: closing dev 0x55e5f15cc6d0, ctl=3
[net] sane_exit: finished.

# sane-find-scanner

  # sane-find-scanner will now attempt to detect your scanner. If the
  # result is different from what you expected, first make sure your
  # scanner is powered up and properly connected to your computer.

  # No SCSI scanners found. If you expected something different, make
sure that
  # you have loaded a kernel SCSI driver for your SCSI adapter.

found USB scanner (vendor=0x06cb, product=0x0081) at libusb:001:003
  # Your USB scanner was (probably) detected. It may or may not be
supported by
  # SANE. Try scanimage -L and read the backend's manpage.

  # Not checking for parallel port scanners.

  # Most Scanners connected to the parallel port or other proprietary ports
  # can't be detected by this program.

... well that's just my fingerprint reader, which doesn't make sense
because in dll.conf I only have net uncommented.  It doesn't seem to be
even trying the net.

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