Aug 272013
 

CUPS_printer

Prerequisites

ALL of the following commands will be run as root. If you are not root already, you can become root by entering “sudo su” as user pi.

Install packages

aptitude update
aptitude install avahi-daemon cups cups-pdf python-cups
  • This will update your package list, and install the packages we need
  • avahi-daemon is a free zeroconf implementation (open source Bonjour replacement)
  • CUPS = Common Unix Printing System – manages the printers for you

This command will take a while, especially after [ ok ] Starting Common Unix Printing System: cupsd. Please be patient here.

Edit /etc/cups/cupsd.conf

nano /etc/cups/cupsd.conf

Comment out the line just below “# Only listen for connections from the local machine.” with an #, and add some new lines, like this:

# Only listen for connections from the local machine.
#Listen localhost:631
#CHANGED TO LISTEN TO LOCAL LAN
Port 631
# Restrict access to the server...
<Location />
  Order allow,deny
  Allow @Local
</Location>
 
# Restrict access to the admin pages...
<Location /admin>
  Order allow,deny
  Allow @Local
</Location>
 
# Restrict access to configuration files...
<Location /admin/conf>
  AuthType Default
  Require user @SYSTEM
  Order allow,deny
  Allow @Local
</Location>

Leave the other lines as they are.

  • This will allow access to the CUPS web interface from other machines than your Raspberry Pi itself (on the local network)
  • We advise you to change the default “raspberry” password for the user “pi” just in case …
  • You can change the port from 631 to something else, but be sure to replace it in the instructions below!

Restart the CUPS service

service cups restart
  • This will restart the CUPS service and reload it’s configuration files

Add the user pi to the lpadmin group

This is necessary to allow you to administrate the printers through the web interface as user pi, later on:

adduser pi lpadmin

AirPrint will have to be enabled after you have added the printers.

 

Add printer(s)

CUPS actually has a very nice web-interface. It apparently has been purchased by Apple in 2007, and is being supported by that huge company and the original developer, Michael Sweet. Maybe that is one reason why it really works quite effortlessly. But, let’s begin:

Open your favorite browser, and enter “https://” + your Raspberry Pi’s IP address + “:” + the port (631 as default).

For example: https://192.168.1.11:631/

CUPS Admin interface

Your browser will most definitely warn you about a security certificate problem. Please ignore it, and continue (or do you sign certificates for your local machines?)

CUPS-interface-raspberry-pi

Hint: CUPS will show up to you in the language your browser indicates to it. Even the directive “DefaultLanguage en” in the configuration file will NOT change that. In other words, to change the language of the CUPS web interface, change your browser default language setting.

Modify CUPS Settings

Click on the Administration Tab, and check “Share printers connected to this system”. Click on “Change Settings”.

cups-administration-tab

At this point you will probably be asked to enter your credentials. If you have added the user pi to the printer management group lpadmin, as per instructions above, you can enter it’s credentials now:

credentials-required

The CUPS server is being restarted.

Connect Printer to CUPS

You can add network printers, or USB printers to CUPS.

Before continuing with the instructions, please ensure that your printer is connected to the network or via USB to the Raspberry Pi , and powered on. You do not need to restart your Raspberry – you can simply plug in your printer right now.

Add a new printer to CUPS

If you have a USB printer, click on “Find New Printers” on the Administration tab (this is called “Verfügbare Drucker auflisten” in German)

cups-find-new-printers

CUPS will take a while – and it should list all printers which it has recognized.

add-kyocera-fs3900dn-cups

Simply add the printer, in this example my trusty Kyocera FS-3900DN (I will only buy Kyocera Laser printers from now on Winking smile). My DYMO LabelWriter 450 was also recognized “out-of-the-box”.

Now simply follow the dialogues and enter sensible values:

add-printer-step-2-example

 

cups-add-printer-iii

(Note: the connection line in the screenshot will say something like “usb://…” for USB printers).

Select your Make and your Model here. A lot of printers are listed. If you don’t find yours, try to find a PPD file for it on the web: A PPD File is a “PostScript Printer Description”” File – it describes fonts, paper sizes, resolutions and other capabilites that are standard for a particular Postscript printer.

Now you will be presented with a dialogue which will have different default options to set up, according to your printer.

Here’s the one for the Kyocera FS-3900DN, for example:

kyocera-fs-3900dn-cups-default-options

Please note: these are default options. If, for instance, the paper sizes your printer supports are not listed here (as is the case for my DYMO LabelWriter 450), simply select the next “matching” one, and set it up under Windows / your Mac correctly.

Now your printer is set up, and you can continue:

Print test page

The CUPS menu “Printers” will list the available printers. By clicking on a particular printer, you can administrate it. For instance, you can print a test page from the Maintenance drop down menu:

cups-test-job

CUPS will show you the progress of the print job.

Adding network printers to CUPS

If you have a network printer, we recommend to use the “Add Printer” button instead, and setting up the printer manually.

appsocket

The CUPS manual recommends to use “HP JetDirect” as it is the most reliable protocol. This works with my Kyocera FS-3900DN.

cups-socket

In the next screen, enter your printer’s IP address, followed by the port (i.e. socket://192.168.1.21:9100 ). There are options to set up secure (encrypted) printing, but this is beyond the scope of this article.

Now you can continue as described above.

Set up AirPrint

In GitHub, there is a script which creates the AirPrint service. In the German article this one translates and elaborates, it is recommended to put it into /opt/AirPrint.

As user root (sudo su):

mkdir /opt/AirPrint
cd /opt/AirPrint
wget -O airprint-generate.py --no-check-certificate https://raw.github.com/tjfontaine/airprint-generate/master/airprint-generate.py
chmod +x airprint-generate.py
./airprint-generate.py -d /etc/avahi/services
service cups restart
service avahi-daemon restart

This will:

  • Create a new directory “/opt/AirPrint”, change into it
  • Download the airprint-generate.py script
  • make it executable
  • execute it, and modify the configuration files in the directory /etc/avahi/services (add an XML description of the new printer service)
  • restart the CUPS and avahi services

If the ./airprint-generate.py command yields an error, like “image/urf is not in mime types, [PRINTER_NAME] may not be available on ios6 (see https://github.com/tjfontaine/airprint-generate/issues/5)”, please refer to the solution in the German article (there is always Google Translate)

The printers should be available now.

 

Install printer on Windows

Open “Devices and Printers”. Click “Add a printer”. Select “Add a network, wireless or Bluetooth printer”.

image

Select “The printer that I want isn’t listed”

image 

image

Select “Select a shared printer by name”, and enter http:// + Raspberry Pi IP + :631 + /printers/ + your printer’s name (called “Queue Name” in CUPS).

For example: http://192.168.1.11:631/printers/kyo-3900

Again, this could probably be changed for encryption – but is outside the scope of this beginner’s article.

Click “Next”, and continue to install the driver. If you can’t select it from the list, try Windows Update (be patient). If that does not work, try to locate the driver on the vendor’s homepage. I had to do the latter for the DYMO LabelWriter 450.

Remember to set up sensible default settings for your new network printer. These settings will override the settings you set on CUPS – thus you CAN actually print to page formats CUPS does not know yet.

 

Add printer to Apple Mac

This Apple KB article should help you to set up your printer on your Mac. Unfortunately there’s no Mac here, when we have access to one, we will test it.

 

 

Problem solving

Can’t find a network printer

Try to add it manually, by using it’s IP address and the information we have given you in this article. If it still does not work, try changing your printer LAN server settings.

Well, what about SAMBA?

CUPS printers can be shared through SAMBA. This is additional configuration overhead, but may add the possibility for Windows machines to automatically download drivers from the Raspberry Pi. This is beyond the scope of this article.

References

Jul 232013
 

Update

We have released dfreerdp (FreeRDP for the DirectFB backend) as a package for the Raspberry Pi. Please go to our new blog post to get it!

Intro

RDP is a convenient way to connect to Windows and also other operating systems with RDP host software, e.g. Linux. RDP transmits display information more efficiently than VLC, as it sees the structure of the screen and it’s elements. It also allows to transmit audio information both ways – playback and recording, share printers, drives, and more. As it is an extensible protocol, efficient video / multimedia playback can be implemented – and has been implemented, albeit apparently only in Windows Media Player.

The Raspberry Pi is a low-power device, with Full-HD (and audio) capable HDMI output.

FreeRDP is a mighty utility to connect to RDP servers, and utilize many of their possibilities. It even supports the video extensions for RDP (in RDP lingo: video redirection virtual channel extension) with ffmpeg. Don’t get your hope up too high right now, though: while theoretically feasible in software, it still would have to be written for both the Raspberry AND the host (it is not a “plug & forget” solution, but the software run on the server has to support it specifically).

The current state: A marriage made in heaven?

Not quite. FreeRDP is easily installed, and used from an X session. But it is … agonizingly slow. Audio playback is in a bad state.

The problem: X adds a very high overhead to any application, but even more so a graphics intensive, such as FreeRDP. Even super-charging the Raspberry Pi with overclocking, Class 10 SD cards, a beefy power supply, etc. will NOT solve this problem! An RDP client compiled specifically for Wayland might, but this is still some way off.

Solution

FreeRDP can be compiled to draw to the Direct Frame Buffer. This eliminates all of the overhead, which X would add. This is perfect for people really trying to use the Raspberry as Windows / RDP thin client. It will work in FullHD resolution (over the local network), with sufficient performance (and 16 bit color depth).

Kudos are in order to the Tao of Mac blog, which had the idea, and the instructions to get me up and running. You rock!

We will release a hardware & software package RDP client, based on the Raspberry, really soon now. If you’re interested, hit me up in the comments.

Step-by step instructions

With all that out of the way, let’s jump into the instructions!

Preparation

We suggest to use a Class 10 SD card, with ample space for the installation & build of the packages (8 GB Class 10 seems sensible). Install the newest Raspbian image, set up your locale and keyboard layout, aptitude update and aptitude upgrade.

Install the necessary packages:

aptitude install build-essential git-core cmake libssl-dev libx11-dev libxext-dev libxinerama-dev libxcursor-dev libxdamage-dev libxv-dev libxkbfile-dev libasound2-dev libcups2-dev libxml2 libxml2-dev libxrandr-dev libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev libavutil-dev libavcodec-dev libcunit1-dev libdirectfb-dev xmlto doxygen libxtst-dev

This should take quite a while.

Download the FreeRDP package (use a sensible location, we will be compiling there later. If in doubt, a sub-folder in your home folder is OK):

wget https://github.com/FreeRDP/FreeRDP/archive/1.0.2.tar.gz

You might also consider checking out the 1.0.3 pre-release version. It might turn stable in a couple of months.

Set up the build environment – this is analoguous to ./configure seen in many other compilations:

cmake -DCMAKE_BUILD_TYPE=Release  -DWITH_FFMPEG=OFF -DWITH_XINERAMA=OFF -DWITH_XCURSOR=OFF -DWITH_DIRECTFB=ON -DCMAKE_INSTALL_PREFIX=~/freerdp

A couple of hints for this:

  • You might want to adjust the –DCMAKE_INSTALL_PREFIX to something more suitable – if you compile as root, it will install the application and the libraries into the folder /root/freerdp otherwise.
    A good choice could be /usr – this way the binaries and libraries will be in the normal search path.
  • turning off FFMPEG means turning off virtual video extension. As discussed before, this is of limited use anyway, right now. But some experimenting might be interesting. FreeRDP also is built modularized on top of FFMPEG, so exchanging that for an omxplayer-like code thingy SHOULD be feasible.
  • Xinerama – is an X extension which allows X applications to span two or more displays a one large virtual display.

Check for the output of this command. It will tell you about skipped options and missed packages. It should find DirectFB amongst others (Found DirectFB: /usr/lib/arm-linux-gnueabihf/libdirectfb.so).

  • pulseaudio: this is a sound server, and another layer on ALSA. It is network capable. Users report varying mileage with pulseaudio and good playback quality. We have tested without the pulseaudio package, future tests will show whether there is an advantage in using it.
  • pcsc – this is for smart card support, most likely you will not need it
  • CUnit – a lightweight system for writing, administering and running unit tests in C – most likely you will not need this, either.

Compile the DirectFB RDP client:

cd client/DirectFB/
make

#optionally 
sudo make install

#for sound support
cd ../../channels/drdynvc
make
sudo make install
cd ../rdpsnd
make
sudo make install

This is all – but this will take quite a while (some hours).

Set up some configuration files

Edit your /etc/udev/rules.d/99-input.rules to be:

SUBSYSTEM=="input", GROUP="input", MODE="0660"
KERNEL=="tty[0-9]*", GROUP="root", MODE="0666"
KERNEL=="mice", MODE="0666"
KERNEL=="fb0", OWNER="root", MODE="0660"

The first line should aready be in the file, add the other three lines.

Optional, but recommended: Edit your /boot/config.txt to contain the following settings:

framebuffer_width=1920
framebuffer_height=1080
framebuffer_depth=16
# for other stuff
gpu_mem=128

arm_freq=800
disable_overscan=1
hdmi_drive=2
hdmi_ignore_edid=0xa5000080

This will

  • set your resolution as fixed [framebuffer_width, framebuffer_height] – be sure to adjust to your needs!
  • set bit depth to 16 – as we will connect to the RDP server using this depth for better performance.
  • ignore anything the monitor will tell the Raspberry – it might lead to blurry edges, otherwise [hdmi_ignore_edid=0xa5000080]
  • overclock the raspberry just a little [arm_freq=800]
  • disable the overscan – remove the black area around the display output on modern LCD monitors [disable_overscan=1]
  • set up the HDMI output to be a real HDMI output and carry audio – this will fix “no sound output” problems [hdmi_drive=2] don’t use this if you connect your Raspberry via DVI or VGA to the monitor

Edit /etc/fb.modes and add a new mode:

# Added as per taoofmac instructions
mode "1920x1080-24p"
   geometry 1920 1080 1920 1080 32
   timings 13468 148 638 36 4 44 5
endmode

You will have to adjust this if you use a different resolution than FullHD. The original article at Tao of Mac has some more resolution examples for you.

Create a new file /etc/directfbrc with the following contents:

system=fbdev
autoflip-window
desktop-buffer-mode=auto
vt-switching
graphics-vt
no-deinit-check
no-motion-compression
no-translucent-windows
memcpy=arm
mode=1920x1080
depth=16
dma
hardware
# for the moment, we need DirectFB's own cursor sprite
cursor

Reboot.

 

Usage

If you specified –DCMAKE_INSTALL_PREFIX to be /usr, you should be able to use FreeRDP DirectFB client without any path prefix, else just prepend your path:

dfreerdp -u "user name" -p secret_password_here -f -g 1920x1080 -x l -z --disable-full-window-drag  --gdi hw --plugin rdpsnd --data alsa --  host:port

Be sure to adjust this command:

  • “user name” should be your user name. If it contains a space, you should keep the quotation marks, else you can loose them.
  • secret_password_here should be your password, obviosly.
  • -g specifies the geometry. Adjust, as necessary.
  • -x = experience (l for LAN), will enable different bells and whistles. You might want to modify that, or use a more finegrained control of which features to enable, and which to disable
  • -z enable compression (useful)
  • –gdi hw – I’m not sure whether this is really necessary
  • –plugin rdpsnd –data alsa —  – this will enable remote sound output on the Raspberry. Drdynvc is said to have better quality, but I could not get it to work unfortunately. And, yes, the trailing double dashes are part of this option.
  • server:port – can be specified as domain or IP adress. The :port can be omitted, if you are connecting to the default RDP port (3389)

If you want sound output on the remote machine, use the –o switch.

 

FAQ

What about keyboard layout?

It will work exactly as you see your keyboard input on the Raspberry console itself. Even the Windows key should work. If your layout does not work on the Raspberry console, consider setting it up using raspi-config

Will this work over WLAN?

Sure it will. Just adjust your WiFi dongle for optimum throughput and latency (yes, literally change its position, tilt, etc. until you find the best performance spot!)

We recommend you the following packes for graphical / console adjustment of Wireless settings:

aptitude install wicd wicd-gtk wicd-curses

Will Skype work?

Not tested yet – enlighten us Smile This will need microphone redirection, too.

Will forwarding of devices work?

Not tested yet – inform us about usb printers, thumb drives, etc.

How can I test sound output on the Raspberry?

aplay /usr/share/scratch/Media/Sounds/Vocals/Singer2.wav -v -V mono

Will performance over WAN networks be OK?

Yes, pretty much – sound output will suffer (a lot), but the GUI will still be quite usable. You might want to adjust the flags to disable some eye candy.

Why do the browsers “stutter” during scrolling?

In my understanding: Unfortunately browsers need a very high degree of control over their screen outputs, and thus they render it themselves, instead of letting Windows do it – RDP sees browser output as image, which is retransmitted when scrolling. Playing with image compression options might alleviate this problem a bit.

Will accessing Linux hosts over RDP work?

Not out of the box – you will need to install an X to RDP conversion software.

In a very quick and rough test, a connection set up by the Scarygliders X11 RDP O Matic as a server backend did not work reliably enough (it was installed on a Pentium IV Linux server). It might do so with some tuning.

Or another backend / solution might do the trick. Looking forward to your input Smile

 

Known problems

  • Flash (isn’t it always on some list?) – will deliver horrible audio performance, native players (Foobar2000) will be OK, though.
  • Video playback – don’t even dream of playing YouTube videos over an RDP connection … the time is not ready yet, the software not written. Care to join a noble cause?
  • WLAN performance will depend on WLAN throughput and latency. The orientation of your dongle – especially nano dongles – will be very important. It can be tuned to a decent performance state, though.
  • I can’t get the new / style switches to work with FreeRDP, fallback to the legacy – switches for now.
  • Sound output: only rdpsnd works, –plugin drdynvc –data tsmf:audio:alsa:plughw:0,0 — will not work – maybe this is a configuration issue, though and some other parameters need to be passed. Drdynvc is said to have better quality. The issue might be with servers with no sound card drivers installed. I did not find an easy solution to this, and I am looking forward to your suggestions.
  • Connection to Linux RDP server compiled with X11 RDP O Matic is not stable for me.

References & further reading

Jun 192013
 

Over my desk (over a big map of the world) I have a sign, which says “The map is not the territory”. It is a quote by Korzybski, a favorite of Bob Wilson’s (of Illuminatus! fame). Also one of me …

A short story about traffic

Today, my brother came to me and wanted the Galaxy Tab I had been using for some days now. It used to be mine, then he took it with him to China, and … actually never really gave it back. Which was mostly fine by me, I got used to it. I did go to Berlin a couple of days ago, and took it with me – I’ve switched the SIMs, installing my Fonic SIM, which includes 300 MB traffic for 10 €.

Today, I was assuming that the SIM was still installed – he asked me to have the phone after I came back from Berlin, probably to chat with some Chinese guys. Turns out it hadn’t been – he had installed his own Alice SIM. And I had been around town yesterday, him probably, too, and the packet switched traffic had not been turned off. It was not used for anything special, mostly the system running updates automatically, probably. Still …

Two things: first, it’s a very expensive mistake (traffic with Alice is about 15 Cent / 100 kB with the first 30 MB being free, if I remember correctly). Second, it’s a predictable mistake – something which can happen easily.

The problem was that our mindstates / maps of the world (in this case of the SIM inside the phone) had not been synchronised. I did not see him exchange my SIM for his SIM, and therefore did not foresee the possible “danger” of using very expensive packet switched traffic. In essence, Alice charges TOO MUCH for this traffic, making the mistake unnecessary expensive.

Windows

But that’s not the point of this blog post. The point is Korzybski’s quote: The map is not the territory.

We build a mental map of everything we interact with – people, machines, animals, transportation, companies … The map can NEVER be the territory (i.e. absolutely cover every aspect of it), it is just a projection of the territory being covered.

Mostly we get by very well. Many people are quite predictable (although I find myself wishing they weren’t in some cases, still hoping for changes …). Transportation mostly is, too. Animals are.

But are machines?

Your vanilla desktop calculator sure is … but your computer (and by computer I mostly mean it’s operating system and software in general) is not.

Windows 8 will force you to try to save your unfinished / unsaved work in 15 minutes before rebooting. There is no easy possibility of preventing that for the user. Windows 7 “kindly” offered to postpone the restart for 15 minutes to 4 hours (if you were present in front of the computer during the critical phase of this dialogue).

Are you expecting your computer to be restarting out of the blue? Emphatically – never. If it would happen every hour, it would be predictable. Annoying still, but predictable – and merged into the mental map. These (rather rare) restarts occur – maybe once each month – and are not in the map.

Nor should they be. Similarly, as with Alice’s heavy penalty for a trivial mistake – this aspect of Windows should be redesigned.

The expected behaviour of the computer by the user should be the default behavior. Novice users should be the ones we model after – bringing their natural experience – interaction with their “normal” surroundings – to bear. The computer should be the one trying to guess the user’s mindstate, and not the other way around.

Some examples

  1. No more restarts without user initiation
  2. No computer initiated focus changes. Never ever. Not even for good reasons.
  3. No “USB key can not be removed” messages without informing the user EXACTLY why (no, “a program is using it” is NOT good enough – even I can’t figure out WHICH program in most cases)
  4. No silent reboots after crashes – the user should be informed about the crash, and if possible about the applications which were open at the last time
  5. Excel should not show a dialogue to recover files, and close it if you double click to open and view one of the files. (This is HUGE)
  6. State dialogues / message boxes should be part of the application, not modal dialogues (the association is easier in this case)
  7. I could go on.

Apple once had a manual on designing user interfaces. I believe we need something like that, too. For the upcoming generation of Web 2.0 apps, and the global switch to Cloud-based App Computing.

Here’s a farewell to all the old cruft, the old problems and bad user interface design. Here’s to less suffering, frustration and angry users of badly designed software. If you happen to be exposed to bad software, do the most sensible thing: turn and run!

May 212013
 

Das ist eine Anleitung wie man eine mit NTFS formatierte Festplatte über den Raspberry Pi im heimischen (Windows-) Netzwerk freigibt. Der Samba-Teil kann (und sollte) natürlich auch mit Linux Partitionen verwendet werden.

penguinadmin

ntfs-3g installieren

Dieses Paket wird benötigt um NTFS – Partitionen größer als 2 TB einbinden zu können. Ich habe diesen Absatz ganz an den Anfang gestellt, damit etwaiige Probleme erst gar nicht auftreten. Sollte man nur Linux Partitionen einbinden wollen, kann das entfallen.

Da der ntfs-3g Treiber sehr ressourcenintensiv ist, sollte man wenn möglich native Linux (ext4 / ext3) Partitionen bevorzugen.

Die dazugehörige Fehlermeldung, falls man es ohne dieses Paket  versuchen würde, würde lauten:

pi@andromeda /mnt $ sudo mount -a
mount: wrong fs type, bad option, bad superblock on /dev/sda1,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

pi@andromeda /mnt $ sudo dmesg | tail
(...)
[23556.245263] NTFS driver 2.1.30 [Flags: R/W MODULE].
[23556.265987] NTFS-fs error (device sda1): parse_ntfs_boot_sector(): Volume size (2TiB) is too large for this architecture.  Maximum supported is 2TiB.  Sorry.
[23556.266018] NTFS-fs error (device sda1): ntfs_fill_super(): Unsupported NTFS filesystem.

Daher installieren wir das Paket ganz einfach:

sudo apt-get install ntfs-3g

Einbinden einer neuen Festplatte

  • Schließe die Festplatte an.
  • Überprüfe mit lsusb ob sie erkannt wurde
pi@andromeda ~ $ lsusb
Bus 001 Device 002: ID 0424:9512 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp.
Bus 001 Device 004: ID 1a40:0201 Terminus Technology Inc. FE 2.1 7-port Hub
Bus 001 Device 005: ID 1a40:0101 Terminus Technology Inc. 4-Port HUB
Bus 001 Device 006: ID 0bc2:3320 Seagate RSS LLC

In unserem Fall ist die Festplatte eine Seagate 3 TB USB 3.0 Festplatte (abwärtskompatibel mit USB 2.0 für den Raspberry Pi). Sie wird erkannt.

  • Liste die angeschlossenen Speichermedien auf mit:

sudo lsblk -o NAME,FSTYPE,MOUNTPOINT,LABEL,UUID,MODEL,SIZE,STATE,OWNER,GROUP,MODE,TYPE 

image

Wenn Deine Ausgabe anstelle der Baumsymbole links komische Zeichen ausgibt, stelle die Zeichensatzkodierung deines SSH-Clients (z.B. PuTTY) auf UTF-8 um. (Klick auf das Bild öffnet eine größere Version)

In unserem Beispiel wird also sowohl die SD Karte von der der Pi gebootet wird ( /dev/mmcblk0 ) mit ihren zwei Partitionen /dev/mmcblk0p1 und /dev/mmcblk0p2, sowie die Seagate Festplatte als /dev/sda mit der einzigen Partition /dev/sda1 angezeigt.

Wichtig an dieser Stelle anzumerken ist, dass die Buchstaben, z.B. das a bei /dev/sda nach der Reihenfolge des Einsteckens vergeben werden. Um jedesmal sicher die richtige Festplatte anzusprechen (z.B. wenn man mehrere Festplatten an dem Pi anschließt, oder zusätzliche USB Sticks / SD Reader / …), sollte man sich daher der UUID bedienen.

  • Liste die UUIDS auf, und verifiziere deren Zuordnung:

ls –lR /dev/disk/by-uuid/

image

 

  • Mountpoint erstellen und /etc/fstab editieren (hier erstmal die Default Einstellungen in dieser Datei zur Referenz):
pi@andromeda /mnt $ sudo su
root@andromeda:/mnt# mkdir /mnt/bigdata
root@andromeda:/mnt# nano /etc/fstab

proc            /proc           proc    defaults          0       0
/dev/mmcblk0p1  /boot           vfat    defaults          0       2
/dev/mmcblk0p2  /               ext4    defaults,noatime  0       1

Der Mountpoint ist nötig, um die Festplatte in das Hauptdateisystem “einhängen” und damit später adressieren zu können  Es sollte sich um einen leeren Ordner handeln, der aber nicht unbedingt in /mnt liegen muss. (Nur das Verzeichnis /tmp sollte man vorsichtig benutzen – es wird bei jedem Neustart geleert).

Wie bereits oben ausgeführt, sollte man hier NICHT /dev/sda1 eintragen, sondern den Pfad mit der UUID, um sicherzustellen dass die richtige Festplatte angesprochen wird.

Wir fügen folgende Zeile in die /etc/fstab hinzu:

UUID=DA0E27C90E279E0F   /mnt/bigdata    ntfs    defaults        0       2

Dabei sind die einzelnen Spalten jeweils mit einem Tab getrennt.

  • die UUID solltest Du mit Deiner UUID ersetzen, die der Partition entspricht die Dich interessiert
  • den Mountpoint ebenfalls mit dem, den Du erstellt hast
  • das Dateisystem ggf. anpassen, falls es nicht ntfs ist
  • defaults bedeutet: standard-Einstellungen (z.B. ob das Dateisystem beim Start automatisch eingehängt werden soll – normalerweise ja)
  • die zahl 0 bedeutet “dump-freq” – Archivierungsfrequenz für das Programm dump – 0 bedeutet “disabled”
  • die zahl 2 spezifiziert die Reihenfolge des Dateisystem-Checks. Nicht-root Partitionen sollten hier eine 2 oder eine 0 (disabled) haben.

 

  • initiales Mounten

Die Partition ist jetzt in /etc/fstab eingetragen, und wir sollten sie jetzt einhängen (nach einem Neustart wird das automatisch gemacht werden):

sudo mount -a

Sollte hier ein Fehler auftreten, schaue bitte den allerersten Absatz nochmal an – hast Du das Paket ntfs-3g installiert?

 

Samba

Samba ist eine “Kompatibilitätsschicht” mit der Windows-Welt von der Linux-Seite her. Es dient nicht nur zur Freigabe von Dateien, sondern auch um z.B. Drucker für Windows zur Verfügung zu stellen.

Aus meiner Sicht ist die Freigabe unter Linux deutlich einfacher als unter Windows selber, also herein ins Vergnügen:

  • wir installieren samba
pi@andromeda ~ $ sudo su
root@andromeda:/home/pi# aptitude install samba samba-common-bin

Samba liest seine Einstellungen aus der Datei /etc/samba/smb.conf – wir schlagen vor die Default Datei als Backup zu verschieben, und eine neue Datei mit einfachen Einstellungen anzulegen. Eine einfache funktionierende Beispieldatei (in Anlehnung an diesen Artikel) ist im folgenden wiedergegeben:

# Global parameters
[global]
       workgroup = HOME
       netbios name = ANDROMEDA
       server string = Samba Server %v
       map to guest = Bad User
       log file = /var/log/samba/log.%m
       max log size = 50
#       socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
       preferred master = No
       local master = No
       dns proxy = No
       security = User

# Share
[bigdata]
       path = /mnt/bigdata
       valid users = my-samba-user
       read only = No
       create mask = 0777
       directory mask = 0777

Die Gruppe global ist ein Sonderbezeichner, es gibt außerdem weitere, z.B. für Drucker. Die workgroup “HOME” hat für uns ganz gut funktioniert, evtl. könnte man noch “WORKGROUP” ausprobieren.

Edit: Durch auskommentieren der socket options Zeile (durch die Raute #)  – wie durch den Kommentar von Basti empfohlen, kann man die Geschwindigkeit auf nahezu den vollen Durchsatz des 100 Mbit/s Ports des Raspberrys anheben! (=> ca. 10 MB/s)

Der netbios name ist der wichtigste Teil unter global. Das ist der neue Windows-Name des Raspberry Pi’s. Es macht Sinn ihn genauso zu benennen, wie den echten hostnamen des Raspberrys (das was üblicherweise auf der Kommandozeile immer angezeigt wird).

Der Name des Shares wird später unter Windows im Pfad eingegeben, ist hier in rechteckigen Klammern, bigdata.

Der vorher erstellte Pfad zum mountpoint sollte hier verändert werden, unter valid users einzutragen ist ein frei wählbarer Name (hier als Beispiel “my-samba-user”), für den wir im nächsten Schritt einen Benutzer anlegen werden.

  • Samba User anlegen, Einstellungen testen, Samba Server neustarten
root@andromeda:/etc/samba# useradd -c "Pi Samba user" my-samba-user

root@andromeda:/etc/samba# smbpasswd -a my-samba-user
New SMB password:
Retype new SMB password:
Added user my-samba-user.

root@andromeda:/etc/samba# testparm
Load smb config files from /etc/samba/smb.conf
rlimit_max: increasing rlimit_max (1024) to minimum Windows limit (16384)
Processing section "[bigdata]"
Loaded services file OK.
Server role: ROLE_STANDALONE
Press enter to see a dump of your service definitions

[global]
        workgroup = HOME
        server string = Samba Server %v
        map to guest = Bad User
        log file = /var/log/samba/log.%m
        max log size = 50
        socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
        local master = No
        dns proxy = No
        idmap config * : backend = tdb

[bigdata]
        path = /mnt/bigdata
        valid users = my-samba-user
        read only = No
        create mask = 0777
        directory mask = 0777

root@andromeda:/etc/samba# service samba restart
[ ok ] Stopping Samba daemons: nmbd smbd.
[ ok ] Starting Samba daemons: nmbd smbd.

root@andromeda:/etc/samba#

Das ist alles was auf Linux Seite erforderlich ist.

 

Einfacher Verbindungstest

image

Man kann jetzt im Windows (falls man den Startknopf noch hat) Dialog “Ausführen” bzw. “Run” auswählen, und den Pfad des neuen SAMBA Shares einfach angeben. In unserem Beispiel “\\ANDROMEDA\bigdata” – ANDROMEDA ist der Pi und bigdata der Share. Man beachte die BACK-Slashes!

Es geht ein Dialog auf, in dem man den ebenfalls bereits auf dem Raspberry Pi angelegten SAMBA-Benutzer und das Passwort eingeben muss, danach öffnet sich ein Explorer-Fenster mit dem Inhalt des neuen Netzlaufwerkes.

 

Dauerhafte Verbindung einrichten

 

Windows 8

image

Explorer aufmachen, Computer anklicken, Reiter “Computer”, “Map Network Drive” klicken. (Map Network Drive kann man auch per Rechtsklick auf “Computer” aus dem Kontext-Menü auswählen).

image

Hier muss man einen (lokalen) Laufwerksbuchstaben auswählen, und den Pfad des Netzlaufwerkes angeben. Bequemerweise kann man auch mit dem Knopf “Browse …” den Ordner auswählen, der Pi taucht in der HOME Gruppe einfach auf. Sollte es das nicht tun, dennoch den Pfad manuell eintippen – das sollte so klappen.

Wichtig ist, dass “Connect using different credentials” angekreuzt ist – wir haben auf dem Raspberry einen eigenen User für die Verbindung eingerichtet.

Ein Klick auf “Finish” ruft den Dialog für die Passwort / Nutzer – Eingabe auf:

image

Hier sollte man die Login Daten des speziell dafür angelegten SAMBA Nutzers eingeben. Es empfiehlt sich in sicheren Umgebungen vermutlich auch, “Remember my credentials” einzugeben, damit sich der Rechner die Zugangsdaten merkt.

That’s it – jetzt steht das Laufwerk zur Verfügung!

 

Windows 7

image

Man öffnet den Explorer, klickt auf “Computer”, und auf “Map network drive”. (Falls man es in der Leiste oben nicht findet, kann man es auch per rechts-Klick auf “Computer” erreichen).

Ansonsten analoges Vorgehen wie bei Windows 8, siehe oben!

 

Windows XP

netzlaufwerk-verbinden

Im Explorer wählt man unter Extras den Menüpunkt “Netzlaufwerk verbinden …” aus …

netzlaufwerk-dialog

es erscheint dieser Dialog, in dem man den Pfad (analog wie bei Windows 8 bzw. 7) eingeben sollte. Anders ist hier, dass man anstelle einer Checkbox “als anderer Benutzer verbinden” eine Art Hyperlink hat, den man anklicken sollte.

verbinden-als

Es erscheint daraufhin dieser Dialog, in dem man die Zugangsdaten die auf dem Raspberry Pi für Samba eingerichtet wurden, eingeben sollte. Ein Klick auf OK hier, und auf Fertig stellen im vorherigen Dialog sollte das Netzlaufwerk verbinden und gleich ein Explorer-Fenster mit dessen Inhalt öffnen.

 

Q & A

Web browser

Ein wichtiger Vorteil von SAMBA ist, dass man den Pi ab sofort unter seinem (Samba) Namen per Webbrowser erreichen kann. Z.B. kann ich einfach andromeda als Adresse angeben, und vorausgesetzt dass ein Webserver installiert ist, wird die Webseite problemlos aufgerufen

image

 

Was für eine Geschwindigkeit kann man erwarten?

Edit: Durch auskommentieren der socket options Zeile (durch die Raute #)  – wie durch den Kommentar von Basti empfohlen, kann man die Geschwindigkeit auf nahezu den vollen Durchsatz des 100 Mbit/s Ports des Raspberrys anheben! (=> ca. 10 MB/s)

image

>> ca. 5 – 6 MB/s

Dabei war die angeschlossene Festplatte eine USB 3.0 Festplatte, es wird das 100 Mbit/s Netzwerk des Raspberrys benutzt, angeschlossen sind das Zielnotebook und der Raspberry am gleichen Gigabit-Switch, und es wird auf eine SSD kopiert, was den Raspberry selber bzw. die USB Implementatoin darauf zu der Engstelle macht.

Das ist natürlich nicht besonders schnell, aber zum Streamen von Filmen, Musik, Dokumenten und für Background-Backups reicht es. Lieber allerdings nicht alles gleichzeitig Smile

Mögliche Gründe für diese niedrige Geschwindigkeit sind – neben den Flaschenhälsen LAN, USB (was sowohl für lesen von der Festplatte als auch für das LAN benötigt wird) das Dateisystem NTFS bzw. der Treiber ntfs-3g dafür. Er ist bekannt, sehr ressourcenfressend zu sein. Vielleicht ist der Default-Treiber für ntfs ressourcenschonender, bei unserem Test mussten wir jedoch ntfs-3g wegen der 3 Terabyte Größe der Festplatte verwenden. Bevorzugen sollte man wie schon erwähnt Linux-eigene Partitionsformate. Wir werden demnächst einen Test damit veröffentlichen.

Die Geschwindigkeit über WLAN (an das Notebook, Raspberry Pi ist weiterhin per LAN angebunden) ist mit ca. 700 KB/s deutlich niedriger – seltsamerweise. Wir würden uns hier über ein paar Erfahrungen von euch freuen (einfach als Kommentar posten). Evtl. liegt das auch an unserer Netzwerk-Topologie / Timing-Problemen …

 

Referenzen / weitere Information

Apr 272013
 

If you have a powerful primary machine (for instance a Dell notebook with an Intel Core i7 processor), it can easily run several Operating Systems and user sessions in / on them side by side – virtualisation is the magic of today’s computing.

The Raspberry Pi, whilst not having enough general purpose power to do really pleasant desktop computing, can very well serve as a “window” to Windows, Linux, MacOS and other more exotic systems running elsewhere. You could run several users off a powerful server machine – all you need is some networking gear, monitors, mice, keyboards, and of course Raspberry Pis.

Your users will enjoy an absolutely silent and energy-efficient client, while the noisy server is hidden away in the basement somewhere (or is in the admin’s room).

Access Windows from the Raspberry Pi

Today we will show you how to access a virtualised Windows desktop from the Raspberry Pi.

VirtualBox

On the host computer which will run the Operating Systems and user sessions for the Raspberry Pi terminals, you should install Oracle’s VirtualBox. (If you are not a fan of Oracle, remember that this was not developed by them but by SUN, and rebranded later on).

The host computer ideally should have hardware virtualisation extensions in the processor, which will allow the guest systems to run much more fluently.

We assume that you run Windows 7+ on the host. VirtualBox also works on Linux, though.

Run VirtualBox, and set up a Windows virtual machine (how to do this is outside the scope of this document).

Networking setup

Here’s the important part to know: initially the virtual network adapters for your virtual machine are set up as “NAT” devices. To be able to access RDP and all other parts freely on your network, the network adapter should be set up as “Bridged Adapter”.

image

This will connect it directly to your network – the machine will be seen outside of the host computer. If you have a DHCP server running, Windows by default will fetch it’s IP address from the DHCP server (e.g. your router).

To be able to access the virtual machine without looking up it’s address first, we recommend to assign a static IP for it ( outside of the area your DHCP server uses to assign IPs).

This is done by right-clicking on the network adapter in Windows, bringing up it’s properties, and editing the IPv4 properties. Whilst being mostly outside of the scope of this short how-to, I’ll share a screenshot with you, which should help you:

image

adjust your settings accordingly.

Note:

The current IP address of your windows computer can be determined by hitting the Windows key, writing “cmd”, pressing Enter (to bring up the command line), and the following command:

ipconfig

image

 

RDP Setup

This part can also be applied to physical machines running Windows.

To allow remote connections to your Windows machine, you have to enable RDP connections first. This is done by hitting the Windows menu, right-clicking on “Computer”, selecting the entry “Properties”.

In Windows 7, you have to click on “Remote settings” in the sidebar of the window which you will see. The dialogue which comes up, will allow you to configure RDP settings.

image

Select “allow connections from computers running any version of Remote Desktop (less secure)”. Click “OK”.

Creating new user

If you do not have a password protected user in your virtual Windows installation yet, you should set one up. You can either create an admin user or a regular Windows user. Using these credentials you will be able to connect to the machine later on. Of course you can also create a new password for the user you already have, if you have decided not to use a password initially.

Raspberry Pi

Start an X session:

startx

Launch the root shell (start menu > Other > X-Terminal as root (GKsu).

Update apt package cache (if you don’t have aptitude, use apt-get):

aptitude update

Install rdesktop package

aptitude install rdesktop

After rdesktop is installed, it is literally just one short command to connect to your virtual Windows desktop:

rdesktop 192.168.1.3

Just replace the IP address with the IP address of your Windows virtual box.

Rdesktop will start a window and allow you to log in to your Windows virtual box. You can click on “Other user” and insert your login credentials here. If another user is logged in at the main machine / via another terminal, Windows might request you to wait for 30 seconds so the other user might allow or disallow your connection.

If you want to launch a full-screen session, you can use the –f switch

rdesktop -f  192.168.1.3

Forwarding sound of the Windows machine to the Raspberry is also possible. Unfortunately it will sound horrible (choppy / barely understandable) – I am not sure what the reason is, as the Raspberry Pi processor is not maxed out (e.g. when streaming Web radio). The sound will sound the same over HDMI and analog output (tested today).

rdesktop -r sound=local 192.168.1.3

Some further options will improve your experience:

rdesktop -z -x lan -P 192.168.1.3

These switches have the following meaning:

-z: enable compression

-x lan: set experience to “LAN” (will show desktop wallpaper, windows while moving them etc.)

-P: enable caching to disk (i.e. the Raspberry Pi’s disk)

Some screenshots

rdesktop-on-raspberry-pi

 

libreoffice-rdesktop-raspberry

Experience

YouTube

YouTube will run, but very choppy – it will max out the Raspberry Pi’s processor. (This is a software problem – rdesktop is probably not using the efficient GPU of the Pi for processing). Sound quality is horrible, actually you can’t really understand it – it’s all chopped up. Sound quality will improve if you minimize YouTube (thereby limiting screen updates which are required, and lowering the load on the Raspberry processor). Sound will still sound choppy, though. All in all not good enough right now.

Sound

As mentioned above, sound quality (if forwarding sound) will be nearly unbearable. Maybe there are some better solutions (i.e. combining a sound streaming server which captures the sound and plays it back on the Pi).

The sound unfortunately will not improve if setting the Group Policy, and forcing sound quality to “high” on Windows. (use gpedit.msc)

Update

The sound problems seem to occur from buffer underruns on the Raspberry Pi side. (see below, xfreerdp).

Desktop experience

Especially with the optimised parameters (-z –x lan –P) the experience is really smooth. For word processing, spreadsheets and web browsing, you will be pleasantly surprised by the reaction speed.

Drawing & photo manipulation will be doable, but in a test with Paint, there was some slugginess.

Actually I see a huge potential in classical desktop / web application workspaces – where you don’t need multimedia, i.e. in a call center where people use web forms and interfaces to access your account with the company.

xfreerdp

xfreerdp is an alternative RDP client. You can install it using

aptitude install freerdp

And use it

xfreerdp -u Wanda -x l -z --plugin rdpsnd --data alsa -- 192.168.1.3

Please note the “x” in front of freerdp here.

This will connect with the user “Wanda”, enable LAN experience, enable compression (-z), and activate sound forwarding through the rdpsnd plugin. The two double dashes after “alsa” and before the IP of the host virtual machine ARE necessary.

Sound will still sound horrible – it will spew out a lot of “underrun occurred” messages on the console. We have tested different options to decrease load, increase latency, use the tsmf option, etc – nothing changed the horrible quality. Right now, the verdict stays the same: great for desktop computing, but not at all for multimedia applications.

There may be some improvement with the current GIT version of freerdp. We have not tested it yet.

Apr 112013
 

As we have posted earlier, we own an old CanoScan LiDE 30. We are very satisfied with this scanner – but unfortunately it does not work on newer versions of Windows (e.g. Windows 7 64 bit, Windows 8) – Canon “forgot” to release updated drivers.

Raspberry Pi networked scanner sharing

A Raspberry Pi is perfect for a small, low volume server application. Today, we have put together all the pieces necessary to use it to attach the Canon scanner to our network, and scan from Windows once again.

BTW: It looks as though the Fujitsu ScanSnap 1300i might also be supported by SANE. This is the replacement scanner for the Canon flatbed scanner we bought – but it can’t scan books, for instance.

Step by step setup guide:

This guide is written for Raspbian. We have tested it with the latest Raspbian version currently available (2013-02-09).

Get the required packages:

sudo su
aptitude update
aptitude install xinetd sane-utils

xinetd is the Internet superdaemon which will start saned, the “Scanner Easy Access Now” daemon when a network connection to it’s port is opened (saned can’t do that on it’s own).

sane-utils contains the saned. (On Archlinux the package is called simply “sane”)

Raspbian automatically sets up the group saned and the user saned for you. It also adds the user saned to the group scanner.

Configure /etc/default/saned so it will start automatically (RUN=yes):

# Defaults for the saned initscript, from sane-utils

# Set to yes to start saned
RUN=yes

# Set to the user saned should run as
RUN_AS_USER=saned

Start saned, and test whether the scanner is recognized. Ideally you should do this as user saned, to see if all access rights for saned are setup correctly. Your scanner should naturally be attached to the Raspberry Pi. If it draws its power through USB, we recommend to use a powered USB hub.

root@raspberrypi:/home/pi# /etc/init.d/saned start

root@raspberrypi:/home/pi# su -s /bin/sh - saned
No directory, logging in with HOME=/

$ lsusb
Bus 001 Device 002: ID 0424:9512 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp.
Bus 001 Device 004: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
Bus 001 Device 008: ID 04a9:220e Canon, Inc. CanoScan N1240U/LiDE 30
Bus 001 Device 007: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse
Bus 001 Device 006: ID 046d:c31c Logitech, Inc. Keyboard K120 for Business

$ scanimage -L
device `plustek:libusb:001:008' is a Canon CanoScan N1240U/LiDE30 flatbed scanner

$ exit

root@raspberrypi:/home/pi#

I have included the # and $ prompt in this listing, so you can distinguish between commands the root user (#) issues and the saned user issues ($)

If you see your scanner here, great. If not – have a look at the documentation and further reading links we will provide at the end of this article.

The USB scanner itself is plug & play – you can attach it to the Raspberry Pi when you feel like scanning, and remove it after you have finished.

Prepare network sharing of the scanner

root@raspberrypi:/etc/xinetd.d# cat /etc/services | grep sane
sane-port       6566/tcp        sane saned      # SANE network scanner daemon

You should see the sane-port line as in the listing. If it is not in there, add it.

root@raspberrypi:/# cd /etc/xinetd.d

root@raspberrypi:/etc/xinetd.d# touch sane-daemon

root@raspberrypi:/etc/xinetd.d# which saned
/usr/sbin/saned

root@raspberrypi:/etc/xinetd.d# nano sane-daemon

This will set up the XInet configuration. Please use the following configuration for the /etc/xinetd.d/sane-daemon file:

service sane-port
            {
              socket_type = stream
              server = /usr/sbin/saned
              protocol = tcp
              user = saned
              group = saned
              wait = no
              disable = no
            }

Note that we used the output from “which saned” in the configuration above. If it is different for you – e.g. on Archlinux – adjust accordingly.

Set up saned to accept connections from your network by editing /etc/sane.d/saned.conf:

# saned.conf
# Configuration for the saned daemon

## Daemon options
# [...]
# data_portrange = 10000 - 10100


## Access list
# [...]
# The hostname matching is not case-sensitive.

#scan-client.somedomain.firm
192.168.1.0/24

#192.168.0.1
#192.168.0.1/29
#[2001:7a8:185e::42:12]
#[2001:7a8:185e::42:12]/64

# [...]

Please adjust the subnet specification 192.168.1.0/24 to your network architecture. You can also explicitly specify single IPs. If you do not edit this file, SaneTwain will hang when contacting your Raspberry Pi scanner server.

Now you can reboot the Raspberry Pi (sudo reboot), and continue to the set up on the Windows side.

Setting up Windows to access the SANE network scanner

We have tested with Windows 7 64 bit & Windows 8 64 bit.

Windows users use “TWAIN” drivers. Luckily, there is an application, which will create a bridge between TWAIN and SANE on the network. The author claims it does not work for 64 bit Windows, but it did work for us. Please report back in the comments about your success / failure stories on different Windows versions.

Download SaneTwain here.

SaneTwain Setup

image

Just enter your Raspberry Pi IP (if you do not know it, “ip addr show” will show you it’s network setup) as the hostname. Port and Username can stay the way they are. Look through the other settings, if you want to. The Mail tab, for instance, offers the possibility to set up an Evernote account you want to scan to.

Before you try to use the TWAIN driver SaneTwain offers, you should set up the hostname using the way we just described (by starting ScanImage.exe).

Scan

Now you’re set up for scanning. Use the “preview” button to acquire a preview, and the “scan” button to save the selected area to a PNG (it will be scanned with better quality, of course). The resolution can be set, also other options.

Wait until the scanner is finished with the preview and has repositioned itself, before you hit the “scan” button.

image

The TWAIN driver works for us, too. (Tested with IrfanView) – this is Windows 8 64 bit. No special tweaks were applied.

Setting up Linux to scan from the network scanner

If you have a Linux box, you can use basically any SANE Frontend to scan using the network.

You need to add the network scanner to a local SANE installation.

Edit /etc/sane.d/net.conf and add the IP of your server. You can specify multiple servers.

image

Test with scanimage –L once again, and after a while you will see your network scanner showing up.

Frontends

Try XSane. Noteworthy is also gscan2pdf which will convert scanned pages to multipage PDFs, and even OCR them for you!

Of course you should be able to scan from another Raspberry Pi on your network, or even the Internet.

simple-scan is a frontend for SANE.

Further Reading & Links

SANE

SaneTwain

How-Tos

We used the following how-tos in building this tutorial. Thanks, guys!

Jan 212013
 

If you, like me, end up having a lot of SDHC test cards (before releasing them to our RPI shop we have to test them!) you may end up wondering whether there is still something important on them, or if you can re-flash them with the newest and greatest Raspbian, XBian or whatever.

the-magician-shows-two-sdhcs-trickUse Raspberry Pi itself

Well – one way is to use the Raspberry Pi itself with another SDHC card which boots, to look at the contents. Raspbian can look at a broad array of different filesystems. Another advantage: you will be able to write to these SDHC cards, too. For instance, you could fix a broken boot sequence or wrong config.txt parameters which prevent you from using the Raspberry Pi.

Read SDHC cards on Windows

But there’s also an option to do this on Windows. If your Windows box happen to be on, or you have only one SDHC and it’s “bricked”, you may want to recover some data from it before reflashing.

We recommend you to get the Diskinternals Freeware Linux-Reader – it will show you a list of partitions, and even has a file preview box where you can see the file’s contents.

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