[sane-devel] Lockup on Network Scan

[CACook at quantum-sci.com]

I've managed to get gscan2pdf installed even though I'm running Debian Testing, and it works when used on the machine local to the scanner (Canon MP460).  But when I use gscan2pdf over the network it locks up the scanner.

I start gscan2pdf and hit the Scan Document.  It recognizes the scanner properly, but when I hit Scan it instantly comes up with "Error during device I/O", and although the machine seems to continue on with the scan, gscan2pdf never shows the scanning bar at the bottom nor comes up with an image.  I Close the error and the Scan Document window, and then the main gscan2pdf window is locked up and I have to terminate it.  The scanner is also locked in Scanning mode, and I have to power-cycle.

I'm not seeing any dmesg errors on the client, and all I see on the server is:
---------------------------------------------------------------------------------
[2321861.324271] ehci_hcd 0000:00:04.1: GetStatus port:2 status 001005 0  ACK POWER sig=se0 PE CONNECT
[2321861.389421] usb 1-2: default language 0x0409
[2321861.390173] usb 1-2: udev 19, busnum 1, minor = 18
[2321861.390176] usb 1-2: New USB device found, idVendor=04a9, idProduct=1716
[2321861.390179] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[2321861.390182] usb 1-2: Product: MP460
[2321861.390184] usb 1-2: Manufacturer: Canon
[2321861.390186] usb 1-2: SerialNumber: 100D89
[2321861.390338] usb 1-2: usb_probe_device
[2321861.390341] usb 1-2: configuration #1 chosen from 1 choice
[2321861.390799] usb 1-2: adding 1-2:1.0 (config #1, interface 0)
[2321861.390861] usb 1-2: adding 1-2:1.1 (config #1, interface 1)
[2321861.390906] usb 1-2: adding 1-2:1.2 (config #1, interface 2)
[2321861.390923] usb-storage 1-2:1.2: usb_probe_interface
[2321861.390927] usb-storage 1-2:1.2: usb_probe_interface - got id
[2321861.391133] scsi22 : usb-storage 1-2:1.2
[2321861.391225] drivers/usb/core/inode.c: creating file '019'
[2321862.393958] scsi 22:0:0:0: Direct-Access     Canon    MP460Storage     0102 PQ: 0 ANSI: 2
[2321862.395282] sd 22:0:0:0: Attached scsi generic sg8 type 0
[2321862.399934] sd 22:0:0:0: [sdi] Attached SCSI removable disk
[2322201.459656] usb 1-2: usbfs: interface 2 claimed by usb-storage while 'saned' sets config #1
[2322204.932218] usb 1-2: usbfs: interface 2 claimed by usb-storage while 'saned' sets config #1
[2322205.952097] usb 1-2: usbfs: interface 2 claimed by usb-storage while 'saned' sets config #1
[2322205.953694] usb 1-2: link qh128-0001/ffff8800af4a1e80 start 14 [2/0 us]
[2322206.124176] usb 1-2: unlink qh128-0001/ffff8800af4a1e80 start 14 [2/0 us]
---------------------------------------------------------------------------------

Both client and server are comprehensively firewalled.  Of course tcp 6566 is open, but are any other ports used, especially UDP ports, that should be open?

Can anyone suggest why this may be locking up?