gschwaer/raspi-scanner-server

Raspberry Pi As Document Scanner Server

In my setup I use a Raspberry Pi 3 Model B Rev 1.2 running Raspbian GNU/Linux 11 (bullseye) and I have a Fujitsu fi-6130 connected to it via USB.

Note: diffs are relative to /etc/..

Scanning Via Network (saned)

Steps

• Install sane (only the required non graphical tools, i.e., sane-utils) sudo apt install --no-install-recommends sane-utils
• Use sudo scanimage -L to localize your scanner, e.g.

  device `fujitsu:fi-6130dj:87644' is a FUJITSU fi-6130dj scanner
  

• Test that the scanner works sudo scanimage -d 'fujitsu:fi-6130dj:87644' -o /tmp/test.png
• Make sane accessible via network in /etc/sane.d/saned.conf

  diff --git a/sane.d/saned.conf b/sane.d/saned.conf
  index 664e459..f133cde 100644
  --- a/sane.d/saned.conf
  +++ b/sane.d/saned.conf
  @@ -19,6 +19,7 @@
  #
  # The hostname matching is not case-sensitive.
  
  +192.168.0.0/24
  #scan-client.somedomain.firm
  #192.168.0.1
  #192.168.0.1/29

  (Check ip addr if that fits your network config.)
• I needed a reboot here for some reason, simply restarting saned did not work
• Now the scanner should be available in the network for SANE clients, e.g. using Document Scanner / simple-scan. But on the client side we need to tell SANE where to look for the scanner. This is what we can do in /etc/sane.d/net.conf, just add the .local or IP address of the server. Mine looks like this:

  # This is the net backend config file.
  
  ## net backend options
  # Timeout for the initial connection to saned. This will prevent the backend
  # from blocking for several minutes trying to connect to an unresponsive
  # saned host (network outage, host down, ...). Value in seconds.
  # connect_timeout = 60
  
  ## saned hosts
  # Each line names a host to attach to.
  # If you list "localhost" then your backends can be accessed either
  # directly or through the net backend.  Going through the net backend
  # may be necessary to access devices that need special privileges.
  # localhost
  athena.local
  

• Fix: For me the scanner was presented to clients as two scanners for some reason, the first works the second doesn't:

  $ scanimage -L
  device `net:athena.local:fujitsu:fi-6130dj:87644' is a FUJITSU fi-6130dj scanner
  device `net:athena.local:escl:fi-6130dj:87644' is a FUJITSU fi-6130dj scanner
  

  It seems the scanner is erroneously detected a second time as an escl scanner. Fix:

  diff --git a/sane.d/dll.conf b/sane.d/dll.conf
  index cc7dfec..bdaad4b 100644
  --- a/sane.d/dll.conf
  +++ b/sane.d/dll.conf
  @@ -34,7 +34,7 @@ epjitsu
  #epson
  epson2
  epsonds
  -escl
  +#escl
  fujitsu
  genesys
  #gphoto2

• (Debug helpers: systemctl status saned.socket, journalctl -f)

Trigger Scan With Scanner Buttons (scanbd)

saned vs scanbd vs scanbm

The honorable saned does not have support for scanner button readout. This is what scanbd does. But saned and scanbd cannot access the scanner at the same time. For this purpose there is scanbm (included in the scanbd package). For network SANE clients scanbm pretends to be saned (uses same port) and if a connection is requested, scanbm pauses scanbd and starts saned. Note that when installing sane/sane-utils, systemd is set up similarly: It only launches saned (saned@.service) when the SANE network port is accessed (saned.socket).

Steps

• Install scanbd: sudo apt install --no-install-recommends scanbd
• Make sure you closed all SANE clients.
• scanbm.socket should have failed to start because the network port was in use by saned.socket, see systemctl status scanbm.socket
• Disabling saned.socket with sudo systemctl disable saned.socket
• For me stopping saned.socket and starting scanbm.socket did not work. I had to reboot for this to work.
• After the reboot, when pressing the Scan/Stop button on the scanner I got a journalctl entry

  Nov 20 21:06:40 athena scanbd[392]: /usr/sbin/scanbd: trigger action for scan for device fujitsu:fi-6130dj:87644 with script test.script
  

• Unfortunately that destroyed everything else again.
  1. The default scanbm config breaks network scanning with saned. Fix:

     diff --git a/scanbd/scanbd.conf b/scanbd/scanbd.conf
     index c2d9333..a235d52 100644
     --- a/scanbd/scanbd.conf
     +++ b/scanbd/scanbd.conf
     @@ -57,7 +57,7 @@ global {
              # the saned executable for manager-mode
              saned   = "/usr/sbin/saned"
              saned_opt  = {} # string-list
     -               saned_env  = { "SANE_CONFIG_DIR=/etc/scanbd" } # list of environment vars for saned
     +        saned_env  = { "SANE_CONFIG_DIR=/etc/sane.d" } # list of environment vars for saned
     
              # Scriptdir specifies where scanbd normally looks for scripts.
              # The scriptdir option can be defined as:

  2. scanimage is now broken when executed from command line. This is because scanimage tries to access the scanner directly and scanbd now constantly claims the scanner. Which is fine for usual operation, because scanbd is smart enough to stop claiming the scanner when it is executing a script due to a button press. And for SANE client scanning, scanbd is paused by scanbm. If you need to run scanimage on the same machine (outside of scanbd scripts) you can either disable scanbd (sudo systemctl stop scanbd) or make scanimage use the network route as well, by changing /etc/sane.d/net.conf

     diff --git a/sane.d/net.conf b/sane.d/net.conf
     index f55f29c..3a8e29b 100644
     --- a/sane.d/net.conf
     +++ b/sane.d/net.conf
     @@ -11,4 +11,4 @@
      # If you list "localhost" then your backends can be accessed either
      # directly or through the net backend.  Going through the net backend
      # may be necessary to access devices that need special privileges.
     -# localhost
     +localhost

     For that to work you will have to prefix the device name with net:localhost:, e.g., scanimage -d 'net:localhost:fujitsu:fi-6130dj:87644' -o /tmp/test.png (works without sudo because we don't access the hardware directly anymore).
• Next we change the scanbd config /etc/scanbd/scanbd.conf a little to our needs

  diff --git a/scanbd/scanbd.conf b/scanbd/scanbd.conf
  index 5d74933..c2d9333 100644
  --- a/scanbd/scanbd.conf
  +++ b/scanbd/scanbd.conf
  @@ -69,7 +69,7 @@ global {
           # scriptdir = /some/path
           # sets scriptdir to the specified absolute path
           # Default scriptdir is <path>/etc/scanbd, this is normally appropriate
  -               scriptdir = /etc/scanbd/scripts
  +        scriptdir = /etc/scanbd/
  
           # Scripts to execute upon device insertion/removal.
           # It can be necessary to load firmware into the device when it is first
  @@ -142,7 +142,7 @@ global {
                   # or an absolute pathname.
                   # It must contain the path to the action script without arguments
                   # Absolute path example: script = "/some/path/foo.script
  -                script = "test.script"
  +                script = "scan-to-share.sh"
           }
           action email {
                   filter = "^email$"

• We put our script scan-to-share.sh at /etc/scanbd/scan-to-share.sh. Ensure owner root:root and permissions -rwxr-xr-x.
  • Create scanner share directory (with access permissions for group scanner, which is used by saned).

    mkdir /srv/scanner-share
    chown root:scanner /srv/scanner-share
    chmod g+w /srv/scanner-share

  • For the script you need img2pdf: sudo apt install --no-install-recommends img2pdf
  • For more scanimage options, check scanimage -d "net:localhost:fujitsu:fi-6130dj:87644" --help
• Fix: scanbd pulls openbsd-inetd | inet-superserver as a dependency and configures it to restart scandm. I guess that is a remnant from pre-systemd times. Now it's quite unnecessary and spams the logs because it fails to restart scanbm on the saned port. It can be disabled by either sudo systemctl disable inetd.service (could shoot you in the foot if you need that for something else (later)) or by changing /etc/inetd.conf

  diff --git a/inetd.conf b/inetd.conf
  index c06bd79..84a1612 100644
  --- a/inetd.conf
  +++ b/inetd.conf
  @@ -35,5 +35,5 @@
   #:HAM-RADIO: amateur-radio services
  
   #:OTHER: Other services
  -sane-port stream tcp nowait saned /usr/sbin/scanbm scanbm
  +# sane-port stream tcp nowait saned /usr/sbin/scanbm scanbm
  

  followed by sudo systemctl restart inetd.service.

Ref:

• https://chrisschuld.com/2020/01/network-scanner-with-scansnap-and-raspberry-pi/
• http://howto.philippkeller.com/2018/02/08/Scan-with-raspberry-pi-convert-with-aws-to-searchable-PDF/
• https://pimylifeup.com/raspberry-pi-scanner-server/

Access Scans Via Network Share (samba)

1. Setup samba for network access to the scanner-share directory.

   # We're doing everything as root
   sudo su
   cd
   # a) Install samba
   apt install --no-install-recommends samba
   # c) Add samba user `scanner-share-user` (with group `scanner` so it has modify permissions on the scanner share)
   useradd -M -g scanner scanner-share-user
   # d) Generate samba password for user
   #    Saved at /root/scanner-share-user.pass
   tr -dc A-Za-z0-9 </dev/urandom | head -c 32 > scanner-share-user.pass
   echo >> scanner-share-user.pass # add newline at end of file
   # e) Add samba user
   cat scanner-share-user.pass scanner-share-user.pass | smbpasswd -s -a scanner-share-user
   echo "Login"
   echo "USER: scanner-share-user"
   echo "PASS: $(cat scanner-share-user.pass)"
   echo "SERVER: $(hostname).local ($(hostname -I | sed 's/ .*//'))"

   You can use the .local instead of the IP address if mDNS is handled correctly in your network.
2. Add the scanner-share to the samba config

   diff --git a/samba/smb.conf b/samba/smb.conf
   index 6a184f9..c2b313e 100644
   --- a/samba/smb.conf
   +++ b/samba/smb.conf
   @@ -234,3 +234,10 @@
   # to the drivers directory for these users to have write rights in it
   ;   write list = root, @lpadmin
   
   +[scanner-share]
   +path = /srv/scanner-share
   +directory mask = 0777
   +create mask = 0777
   +writable = yes
   +public = no
   +

3. Restart samba sudo systemctl restart smbd
4. On the client, try to access smb://SERVER/scanner-share/ (use SERVER from above), e.g., with a file explorer (nautilus/nemo/...). It should ask for a login. (Use USER and PASS from above. Domain should be WORKGROUP or see server's /etc/samba/smb.conf.)
5. (opt) Add a bookmark in your file explorer for ease of use.
6. (opt) By default samba will advertise printer drivers for windows machines in a directory named print$. If undesired, disable this

   diff --git a/samba/smb.conf b/samba/smb.conf
   index b055e0f..73b7412 100644
   --- a/samba/smb.conf
   +++ b/samba/smb.conf
   @@ -221,12 +221,12 @@
   
    # Windows clients look for this share name as a source of downloadable
    # printer drivers
   -[print$]
   -   comment = Printer Drivers
   -   path = /var/lib/samba/printers
   -   browseable = yes
   -   read only = yes
   -   guest ok = no
   +;[print$]
   +;   comment = Printer Drivers
   +;   path = /var/lib/samba/printers
   +;   browseable = yes
   +;   read only = yes
   +;   guest ok = no
    # Uncomment to allow remote administration of Windows print drivers.
    # You may need to replace 'lpadmin' with the name of the group your
    # admin users are members of.

Ref:

• https://pimylifeup.com/raspberry-pi-samba/
• man smb.conf

Notes

• I tried to improve on the image processing done by the scanner driver using some imagemagick (see ./test.sh). But that was too much for the Pi, so I will keep using the slightly less pretty defaults.
• I wrote some (German) labels for the different function modes that I printed and taped onto the printer (./Function List.ods).

Future Work

• Maybe checkout unpaper
• OCR, but definitely not on the Pi. Maybe putting a script in the scanner-share, so the users can post process their scans.