Debian

GNAT 2012 for Debian Wheezy

For purposes known mostly within our company, I’ve created a magic makefile that takes care of most of the work involved with getting a GNAT 2012 (and up-to-date various support tools) up and running on a Debian.

The makefile requires you to download some files manually, but that’s okay, as it gives you a great opportunity to visit AdaCore’s libre webpage. The readme file explains it in more detail.

At this point, the makefile will build (and/or install) the following projects.

  • GNAT 2012 – binary
  • GNATCOLL (Gnatlib) – SVN build
  • AWS (Ada Web Server) – Git build
  • Florist GPL 2012 release
  • XML-Ada 4.3 (release)
  • Yolk (AWS support library)
In time, the makefile will be expanded to support more libraries and projects.

The makefile can be found at GitHub, hope you find it useful or want to contribute.

Persistant enumeration of network interfaces across hardware addresses

If you’ve ever created a Linux virtual machine image for distribution, you have probably encountered this problem. The Virtualization is not really important – the problem exists on VirtualBox, VMWare, KVM, Xen and others supporting Linux guests.

So, what is the issue exactly?

The problem is that when you recreate a a virtual machine using an existing image, a new MAC address is generated. Udev sees this new address and creates a static name for it – e.g. eth1. Keeping the original – now removed – eth0 in the persistant naming file.

This interface typically does not exist in the /etc/network/interfaces file, and therefore is never “upped”. This leaves you with a machine that has no network connection out of the box.

Well, how do I fix it then?

The simple solution is to remove the /etc/udev/rules.d/70-persistent-net.rules file and reboot.
This means you have to remove the file as the last thing you do before shipping the image. I you make changes to the image, and reship it – you must do this every time. Plus it prevents easy redistribution of your image.

So, I’ve placed a small bash script at /usr/local/bin/reenumerate_interfaces and called it from /etc/rc.local.

This script also have the advantage, that you do not have to reboot the machine for the changes to take effect.

#! /bin/sh
 
echo Re-enumerating the network interfaces...
 
# Stop networking
/etc/init.d/networking stop
<pre lang="bash">
# Get the drivers and bounce the NICs
lspci -nnv | awk '{
if ($0 ~ /^$/) { getDriver = 0; }
if (getDriver == 0 && $0 ~ /.*Ethernet controller.*/) { getDriver=1; }
if (getDriver == 1 && $0 ~ /.*Kernel driver.*/) { printf ("%s\n", $5); }
}' | sort | uniq | while read a; do
 
echo Unloading network module $a from kernel space
rmmod $a
done
 
# Remove the static enumerations
rm /etc/udev/rules.d/70-persistent-net.rules
 
echo Reloading driver via udev
# Tickle udev
/sbin/udevadm trigger
 
# Start networking
/etc/init.d/networking start

Yet another goodbye

For those who are about to halt -p, we salute you.

I’m moving out – of my first vserver that is.

I have had the server running for, well

lucretia:~# uptime 
 19:19:59 up 700 days, 22:51,  2 users,  load average: 0.02, 0.06, 0.02

Wow.. Time flies.

I have been migrating the services running in the machine to another, server. Not is the time to do the inevitable.

Sorry old chap, better you than me.

lucretia:~# halt -p

Broadcast message from root@lucretia (pts/1) (Fri Sep 30 19:23:24 2011):

The system is going down for system halt NOW!
lucretia:~# Connection to lucretia.greenpc.dk closed by remote host.
Connection to lucretia.greenpc.dk closed.

Of course, prior to this, I made sure to make a complete copy of the file system like so. Isn’t rsync the best tool?

rsync --progress -poazuHK -e ssh --delete --exclude /proc --exclude sys --exclude dev / home.greenpc.dk:/mnt/primary/backup/lucretia.greenpc.dk

Buffalo WLI-U2-KG54L on Debian

The dongle under treatment

I have a Buffalo WLI-U2-KG54L USB wifi dongle. It very convenient as my router and access point is placed in the basement, and I sometimes have computers on the main floor that do not have built-in wifi.

The dongle works out-of-the-box™ on Ubuntu, but as debian are more restrictive, it need a bit more work.

You can find the instructions here: http://wiki.debian.org/zd1211rw

And instructions on how to activate it here: http://wiki.debian.org/WiFi/HowToUse. The part about wpa_supplicant is most relevant, as network manager just works when the device works.

Proftpd and LDAP on Debian Squeeze

This is a short howto (hopefully) providing enough information to install Proftpd and use LDAP as user database.

Background

I have become obsessed with LDAP – at least for the time being. It seem to be the answer to my redundancy and distribution plans.

A production server is in the process of being converted (migrated actually) to have a single SSO LDAP structure.

A virtualization host crash (thank you Linode) forced me to move a couple of sites onto this new fancy LDAP server. Shortly after, a user prompted me about the lack of FTP on the new webhost.

Now the shoe needs to fit.

Installing the required packages

This is the easy part.

# apt-get install proftpd-mod-ldap

The LDAP module will depend on the proftpd server so this is really the only thing you need to install.

Requirements for the LDAP server

The LDAP module for Proftpd is hard coded to lookup only users of objectClass: posixUsers which in my opinion is less intuitive than having a specified schema for proftpd.

An example .ldif is shown below. I have added objectClass: domain, which is unnecessary.

The uidNumber and the gidNumber maps the uid and gid on the system. 115 is proftfd user and 65534 is group nobody. From a ftp client owner will appear as domain.tld or whatever you specify as uid.

version: 1

dn: dc=domain.tld,ou=webhosting,dc=example,dc=com
objectClass: domain
objectClass: top
objectClass: posixAccount
cn: domain.tld
dc: domain.tld
gidNumber: 65534
homeDirectory: /var/www/domain.tld/www
uid: domain.tld
uidNumber: 115
loginShell: /bin/false
userPassword::

Configuring the authentication

First you need to edit /etc/proftpd/ldap.conf to match you LDAP setup. Somthing like this is appropriate.

<IfModule mod_ldap.c>
  LDAPServer ldap://example.com/??sub
  LDAPDNInfo "cn=proftpd,dc=example,dc=com" "password"
  LDAPDoAuth on "ou=webhosting,dc=example,dc=com"
</IfModule>

notice the ??sub after the ldap. This is very important as it specifies the search scope. The configuration parameter LDAPSearchScope is apparently ignored.

Again, a sour comment; the bind should have been done as the user logging in, and not as a dedicated user. Admin is a bad choice – create a dedicated user. Besides, the /etc/proftpd/ldap.conf is world readable!

Next you have to tell proftpd to load the module.
Uncomment the line

LoadModule mod_ldap.c

in /etc/proftpd/modules.conf.

Now you have to uncomment the line.

Include /etc/proftpd/ldap.conf

in /etc/proftpd/proftpd.conf to load the Ldap configuration.

Finally:

While editing proftpd.conf you should also lift the RequireValidShell restriction (or give the user a valid loginShell parameter. If do not do this, you will not be able to log in.

Now is the time to take a look at the standard proftpd configuration and make sure that anonymous login is disabled and ditto /etc/passwd users.

HD time-lapse movies with Motion and Linux

NSLU2 with webcam
The system

Background

I have previously experimented with time lapse videos, but wanted a more dedicated platform which could be set up, and run pretty much anywhere.

This is the first iteration, where the the purpose is to get the system up and running with headless operation.

Components

The original idea was to use a PC Engines alix1d system board in a box1c enclosure, but unfortunately the board I had was running very unstable – so I brought in an old friend of mine:

The Linksys NSLU2 aka. “slug”. The one I had ran Debian 5.0 Lenny, but had to be upgraded in order to get the webcam to work.

I recklessly tried doing a dist-upgrade, but ended up with bricked slug. Guess a fresh installation was the right answer indeed.

Debian Squeeze on a NSLU2

Due to a required proprietary firmware, the official Debian 6.0 installer does not ship with support for the on board Ethernet controller – which is bad because this is the only way of communicating the the device. Well, technically you can use the serial pin header or an USB Ethernet device, but I think I have burned the circuit for the serial port in a previous modding attempt :-\

There is a few guides that  give you directions on how to add the proprietary firmware to the installer image, and after about 5 reflashes I finally had one that worked.

Before starting the installation, I checked around for known installation errors. The installation takes about 5 hours, so you really want to get i right the first time.

I learned that others had experienced out of memory errors during the installation. Though luck.

To the rescue came Martin Michlmayr. He has the answer to all my quarrels; a compiled guide, with a complete Debian 6 userspace and kernel. This saved me a lot of time.

 Install and configure Motion

You can install motion by

apt-get install motion

as root or via sudo.

On Debian (Squeeze in my case), Motion is disabled by default – as many other services. Enable it, as mentioned in the notice:

Not starting motion daemon, disabled via /etc/default/motion ... (warning).

Setting the value start_motion_daemon to yes in /etc/default/motion as such:

start_motion_daemon=yes

 

The trick to disable motion detection in Motion, is to set the threshold to 0 in the config file:

threshold 0

Enabling time-lapse by setting the following in /etc/motion/motion.conf:

# Use ffmpeg to encode a timelapse movie
# Default value 0 = off - else save frame every Nth second
ffmpeg_timelapse 10

In this case, I take a pictures every ten seconds.

You should also adjust the width and height parameters, and the target_dir.

You can also get a copy of my preconfigured motion.conf by running the following set of commands

/etc/init.d/motion stop
mv /etc/motion/motion.conf /etc/motion/motion.conf.orig
wget http://retrospekt.dk/files/motion.conf -O /etc/motion/motion.conf
mkdir /home/motion
chown motion:motion /home/motion
chown root:motion /etc/motion/motion.conf
chmod g+r /etc/motion/motion.conf
/etc/init.d/motion start

An example can be seen here: http://retrospekt.dk/files/timelapse.mpg

How to install LabVIEW on a Debian Machine

Labview ships prepackaged to install on rpm based Linux machines (Redhat, Mandrake and so on). But it is quite simple to convert and install it on a Debian machine instead.

The machine I will be using is a Thinkpad T40 with Debian Lenny installed, it should be the same for the current stable (Etch) but this is yet to be confirmed.

First we need to install alien

# aptitude install alien

The conversion process is quite simple, all you have to is to type

# alien -d *.rpm

And after some time (about 15 minutes or so on my laptop) you should be left with a bunch of .deb files.

You might have guessed it.. to install:

# dpkg -i *.deb

Now for the hacking part, when you try to run Labview all you get is this error:

/usr/local/natinst/LabVIEW-8.2/labview: symbol lookup error: /usr/local/natinst/LabVIEW-8.2/linux/libOSMesa.so.4: undefined symbol: _glapi_add_entrypoint

To work around this you need to install libosmesa (of current writing libosmesa6)

# aptitude install libosmesa6

and relink

# (cd /usr/local/natinst/LabVIEW-8.2/linux; rm libOSMesa.so.4; ln -s /usr/lib/libOSMesa.so.6 libOSMesa.so.4)

And it works! If you feel like it, you can also put a little icon on your desktop or in your Applications menu (this part is for gnome), this is the contents of the labview.desktop file with my corrections. It originates from /usr/local/natinst/LabVIEW-8.2/linux/gnome/gnome/apps/Applications/labview82.desktop and there is a similar file for KDE in the /usr/local/natinst/LabVIEW-8.2/linux/kde folder for those who want to make a KDE shortcut.
Contents of labview82.desktop

[Desktop Entry]
Name=LabVIEW 8.2
Comment=LabVIEW Graphical Dataflow Programming Environment
Exec=/usr/local/natinst/LabVIEW-8.2/labview
Icon=/usr/local/natinst/LabVIEW-8.2/linux/icons/labview-3d.xpm
Terminal=false
Type=Application
Categories=Application;Development;X-Red-Hat-Base

This file can be placed either in ~/.local/share/applications/ or in /usr/share/applications