blog.crox.net

When performing tests you may sometimes want to send specially crafted icmp packets. hping is a handy tool for that.

However, the default behavior is to refuse to send "unsupported" Type/Code combinations. eg

hping3 -c 1 --icmp -C 33 -K 0 192.168.70.1
HPING 192.168.70.1 (wlan0 192.168.70.10): icmp mode set, 28 headers + 0 data bytes
[send_icmp] Unsupported icmp type!

Fortunately, there is an (undocumented) --force-icmp option that you can add to bypass the check:

hping3 -c 1 --icmp --force-icmp -C 33 -K 0 192.168.70.1
HPING 192.168.70.1 (wlan0 192.168.70.10): icmp mode set, 28 headers + 0 data bytes

--- 192.168.70.1 hping statistic ---
1 packets transmitted, 0 packets received, 100% packet loss
round-trip min/avg/max = 0.0/0.0/0.0 ms

In Ubuntu Karmic (and possibly Jaunty ?), when you install libsane, it adds a file /lib/udev/rules.d/40-libsane.rules which contains rules that match on supported scanners and set the environment variable "libsane_matched" to "yes".

This in turn triggers the following in /lib/udev/rules.d/70-acl.rules:

# USB scanners
ENV{libsane_matched}=="yes", ENV{ACL_MANAGE}="1"

<snip>

# apply ACL for all locally logged in users
LABEL="acl_apply", ENV{ACL_MANAGE}=="?*", TEST=="/var/run/ConsoleKit/database", \
  RUN+="udev-acl --action=$env{ACTION} --device=$env{DEVNAME}"

In the end, the result is that an ACL is created for the device, which allows locally logged in users to use it (read/write permission). eg for my scanner:

~# lsusb
Bus 001 Device 005: ID 04b8:011c Seiko Epson Corp. Perfection 3200
~# ls -l /dev/bus/usb/001/005
crw-rw-r--+ 1 root root 189, 4 2009-12-28 00:11 /dev/bus/usb/001/005
~# getfacl /dev/bus/usb/001/005
getfacl: Removing leading '/' from absolute path names
# file: dev/bus/usb/001/005
# owner: root
# group: root
user::rw-
user:crox:rw-
group::rw-
mask::rw-
other::r--
~#

However, I also wanted to allow access to the scanner from other workstations through saned. In older Ubuntu versions, you could just add saned (or whatever user the service runs as) to the scanner group. This no longer works since the device belongs to root:root, and ACLs are added for specific users. The solution that works for me is to create a file /etc/udev/rules.d/99-sane-group.rules with the following contents:

# change group to scanner for sane devices
ENV{libsane_matched}=="yes", GROUP="scanner"

Then you just need to run

sudo udevadm trigger

and the group of the device magically changes to scanner.

Of course you could also add a similar rule specifically for a certain device instead, in my case this would work too:

ATTRS{idVendor}=="1d6b", ATTRS{idProduct}=="0002", GROUP="scanner"

To check that it worked, run the following:

sudo su -s /bin/bash -c 'scanimage -L' saned

Faced with a noisy Dell Precision 490 computer running Ubuntu Karmic, I found an easy way to reduce the noise level to an acceptable threshold. (fancontrol did not help since it seems not to be compatible with the chipset used by Dell at least on this computer.)

Step 1, install i8kutils:

sudo apt-get install i8kutils

Step 2, add i8k to /etc/modules:

sudo sh -c 'echo i8k >> /etc/modules'

Step 3, edit /etc/default/i8kmon so that it looks like this:

# /etc/default/i8kmon



# Change to one enable i8kmon

ENABLED=1

I8KMON_ARGS="--daemon --nouserconfig --auto"

Step 4, reboot and enjoy!

This is a copy of a post I made to the isdn4linux mailing-list.

The attached patch adds support to mISDN-1_1_9_2 for the Eicon DIVA USB ISDN adapter (071d:1005).

The bits I've added to hfcs_usb.c are from kernel 2.6.31. So far the adapter works fine for me (tested with 1 and 2 concurrent calls to asterisk 1.4.26.1 with chan_misdn).

You can get the patch here: misdn-1.1.9.2-Eicon-Diva-USB.patch.

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I've recently acquired an HP Photosmart Premium C309a all-in-one device (CC335B). I planned to use the device mainly for its scanner with duplex-capable automatic document feeder (ADF), in order to archive our mail electronically (more on that later). But I was also happy to get a device which can replace man different ones: it is also a fax, and a nice printer for documents, pictures and even (special) CD/DVDs.

I already have a Canon Selphy CP740 dye sublimation photo printer, which I like very much but has two limitations: 1. it's limited to 10x15 format (4x6 in), and 2. it seems that it's impossible to get the printer to work correctly when attached to a PC as a usb printer. It works nicely in stand-alone mode (ie printing from a digital camera with PictBridge or directly from a CF card), but so far I've only managed to waste paper and ink when trying to print directly from the computer. (I've even installed a fresh Windows XP to try the software from Canon, it didn't work any better.) So the good quality of the HP as a photo printer was one more argument in its favour.

Here is how I was able to print borderless photos directly from The Gimp:

1. If you want no border at all, the image should obviously have the same aspect ratio as the paper you'll print on. If necessary, use "Image" -> "Canvas size" or the Crop tool to adjust it.

2. "File" -> "Page setup": select the correct printer and paper size

3. "File" -> "Print":

- in "Page setup", select "Photo Tray" as paper source
- in "Image Settings", check the box "Ignore Page Margins", then adjust Width/Height so that the picture fills the paper (if it doesn't, get back to step 1)
- in "Advanced", select "Photo" as Printout mode, and "1200 dpi, Photo, Full Bleed" under "Resolution, Quality, Ink Type, Media Type" ("Controlled by 'Printout Mode'" seems to do as well)

4. Click "Print"