Everything you ever wanted to know about Debian...

But were afraid to ask... Well, this may be more true for folks who heed the advice to RTFM (Read The Fine Manual).

Debian is a GNU/Linux distribution of Free Software.

Since there is such an overwhelming volume of documentation on Debian (both old and new), it can be bewildering to know where to start. This guide tries to highlight those concepts which are actually key to getting things working, and which can be picked up later as you go along and get more familiar with the structure of the system. It's best of course if you can also have a chat with a friendly Debian user.

A lot of these Debian hints are thanks to the explanations by Rick Moen (rick@linuxmafia.com). Rick has much more Debian info in his Debian Knowledge Base.

Debian as compared to other linux distributions

If you would like to run a system which you can upgrade over time without needing to reinstall it whenever there is a "release" from the distribution vendor, then the Debian distribution is a very attractive choice. The Debian distribution provides binaries for a great variety of architectures, so not a lot of time need be spent by your local system to get it installed. Using the latest Debian "netinst" (see below), you can get a system up and running using only a single, small CD-ROM image.

The reason "releases" have so little relevance when running Debian, is due to Debian's policy, as well as its concept of "tracks". These tracks have the names Stable, Testing and Unstable (Unstable is also known as "sid", after the neighbor kid who was a menace to all the toys in the movie "Toy Story"). These tracks are like symbolic links. A better analogy might be to think of train tracks: in Debian there are three trains (the releases) running along three different development tracks. When a release occurs (for example when the "sarge" train recently reached the end of the Testing track and was shunted onto the Stable track), the Debian maintainers simply change the symlinks to point Stable to what used to be Testing (effectively putting this new and improved train into wider service, now that it has been proven stable), and Debian continues development. Of course, the analogy to train tracks isn't perfect, because the Unstable track would have to be infinitely long. Releases in Debian are not such a major event, the way they tend to be with other distributions. Folks running on the Stable track will just see an unusually large volume of updates the next time they update their systems.

Debian Distribution Policy

The concept of a distribution policy is a tricky one to explain, and until you've experienced using a distribution with a policy for a while, you really don't know what you're missing. Having a policy is the reason Debian is so smoothly upgradable and maintainable, as compared to those other distributions which don't have a clear policy. Initially I had thought that the reason Debian was so upgradable had something to do with the packaging format (debian uses deb packages, whereas many other distributions use RPM packages), but Conectiva uses RPM and it too has a policy which allows it to be upgradable. I'll try and update this section with a better explanation of the whole "policy" concept than these vague ramblings.

1. Starting out on the "Stable" track

Let's start our Debian exploration on "Stable". If you are familiar with RPM-based linux distributions, up until recently when sarge was released, running on the Stable track felt a bit like a trip back in time. The Stable track is the one on which you can be sure to always get the security updates automatically. To see the names of the current release on each of the tracks, consult the file debian/dists/README here. At the beginning of 2005, the Stable track pointed to the release with the name "woody". Now it points to "sarge".

For example, an official Debian CD distribution of Sarge has the name:
  Debian GNU/Linux 3.1 r0a_Sarge_
When originally installed from CD-ROM, the file /etc/apt/sources.list contains only references to the CD-ROM set the distribution was installed from, so to allow you to update the distribution and install new packages from the network, it would need to be modified to include references to a "Debian Mirror" as explained in the next section.

2. Updating to "the latest"

To update a Debian installation done from CD-ROM on the Stable track to the latest versions of the packages available on the Stable track, you'll need to replace the contents of /etc/apt/sources.list with the following:

  deb http://security.debian.org             stable/updates main non-free contrib
  deb http://http.us.debian.org/debian/      stable         main non-free contrib
  deb-src http://http.us.debian.org/debian/  stable         main non-free contrib
  deb http://non-us.debian.org/debian-non-US stable/non-US  main non-free contrib

If you're behind a proxy server, set the following in your environment, so that apt-get knows how to find its way to the Debian mirror servers, by telling it about your proxy server. This can be done by setting the http_proxy environment variable:

  export http_proxy="http://your-proxy.your-domain:80"

To update the package catalogues and then update all of the installed packages to the latest revisions available, run the command:

  apt-get update
  apt-get dist-upgrade

If you prefer, you can download the packages first (as this takes a long time) and then install them when you are ready, using the --download-only flag, e.g. as follows. There's even a tool called cron-apt to automate this procedure for you.

apt-get update && apt-get --download-only dist-upgrade

After this, you will be up to date on the Stable track.

Now that sarge is released (3.1r0 was released Monday, June 6th, 2005), the stable track now has all of the goodies and I hope it's not too much of a stretch to say that even developers will be happy with the recent versions of tools and libraries.

3. Moving to the Testing track.

There's a lot less of a need to do this now that Sarge is released as stable, but if you need to follow development closely then to change your distro from the Stable track to the Testing track, the file:

should be changed to the following:

  deb http://security.debian.org stable/updates main contrib non-free
  deb http://security.debian.org testing/updates main contrib non-free
  deb http://http.us.debian.org/debian/ testing main non-free contrib
  deb http://non-us.debian.org/debian-non-US testing/non-US main contrib non-free

Note that the security deb source should still be selected from the Stable track, as well as the Testing track, because usually security updates are made available on the Stable track first.

4. Update the core packages first...

This step may be unnecessary nowadays because when you do

  apt-get update && apt-get dist-upgrade
the Debian package manager will successfully upgrade everything from stable to testing. It will even ask:
  Do you want to upgrade the system?
meaning do you want to upgrade your libc6 and so on.

I'll leave the description of this step in here for now, as it's still useful to know the names of the core packages. The step is as follows: update the core packages of the system first, before embarking on the full distro upgrade, since these packages are the main ones that will be used to do the upgrade work:
  apt-get update
  apt-get install perl libc6 dpkg apt apt-utils debconf

5. Upgrade the distro...

Run the distro upgrade step again:

  apt-get update
  apt-get dist-upgrade
After this, you will be up to date on the Testing track.

Getting to know the Debian package management tools

The catalogue listing all the details about all the packages available worldwide (from sources you have listed in your /etc/apt/sources.list configuration file) is located in:


The filenames in this directory are rather long. The files ending in _Release contain the header information for the catalogue archive. Using this, you can tell which Track a given archive corresponds to, what component it refers to, who (or what) the origin (or publisher) of the catalogue is, what the label is, and the Architecture the catalogue is for.

The files ending in _Packages contain complete lists in ASCII of all the packages. To update these catalogues, use the command:

  apt-get update

This will refresh the catalogues, according to whatever sources you have specified in your /etc/apt/sources.list. It also merges all available packages into /var/lib/dpkg/available. The status of all packages is listed in file /var/lib/dpkg/status.

Layering of Debian package management tools

The Debian package management tools are organised in a hierarchy, according to their capabilities, level of abstraction, and the user interface they provide. At the top level are the tools dselect, adept and aptitude. If you have a somewhat older (slower) system, you may prefer to only download the packages, but install them later. You can use the -d flag with aptitude to only download the packages. There's also debfoster, useful for finding and removing packages you no longer want around to help with security, or just to cleanup and save disk space. The next level down is apt-get (apt is the "Advanced Packaging Tool", which is the most commonly used tool from the command line), and finally the lowest-level tool is dpkg (which although it is supposedly the least user-friendly, dpkg is sometimes the simplest tool to use to get the job done -- you may find yourself resorting to using dpkg when you don't happen to have very good network connectivity).

Shiny New Debian CDs

If you want to update your system from a new set of CDs, you'll first need to add the catalogues from the new CD-ROM source. To do this, use apt=cdrom. After that, just update the system as usual using apt-get dist-upgrade.

Finding that Elusive Package

Use the utility apt-cache to search the catalogue for packages you'd like to install, or to get information about packages before installing them:

  apt-cache search nasm
  apt-cache showpkg intel2gas

The Debian website also maintains the Search package directories tool, which for example is great for getting package details for other architectures.

Searching Debian Source Code

New: browseable view of all Debian-related source code, and Debian Code Search Tool which can search all 130 GiB of source code within Debian.

Finding the kernel package

Kernel packages for Debian can be found in /var/lib/apt/lists by searching for the string kernel-image, e.g. for the PowerPC architecture, one of the Stable kernel packages had the name:


Cleaning up for extra disk space

To clean the cache of Debian's packages in /var/cache/apt/archives the following commands can be used:

  apt-get clean
  apt-get autoclean

Sometimes, an operation like apt-get dist-upgrade might get interrupted due to running out of space in /var. In that case, after using the above apt-get clean command to free up some space, you can resume using:

sudo dpkg --configure -a

Forcing things

Sometimes you might need to "force" things to get them to update, due to dependency issues. It's best to check carefully before doing this sort of thing, though:

  dpkg -i --force-overwrite knoqueror
  apt-get -f dist-upgrade

Exploring the installed packages

To list all of the Debian packages already installed on your system:

  dpkg -l
  dlocate -l

To use grep to narrow the list of packages to those with names that contain a specific string, remember to add the environment setting for COLUMNS like in the following example, as otherwise the default narrow name field may truncate the name you're searching for:

  COLUMNS=200 dpkg -l|grep whatever
  COLUMNS=200 dlocate -l whatever
To show the installation status of a package (and its description, once it's installed), use dlocate -s:
  dlocate -s tuxpaint
You can also use wildcards in the search string provided to dpkg -l, as in the following example:
  COLUMNS=200 dpkg -l '*whatever*'
The reason the dpkg command needs COLUMNS to be set is because it recognises when its output isn't a terminal, and truncates the package name column so that it fits in a narrower width. Another method for searching for packages is thanks to Adam D. Barratt:
  dpkg-query --show --showformat='${Package;-50}${Version}\n' 'libgnomevfs*'

To list the contents of a specific Debian package already installed on your system:

  dpkg -L libgtk2.0-dev

To figure out which package a given file on your system belongs to:

  dpkg --search /usr/lib/libgtk-x11-2.0.a

Cloning another system

If you already have one system, e.g., systemA set up with all of your favorite packages, and you're installing another system and would like to reuse the same configuration, then to grab the package configuration of systemA, you would use:
  dpkg --get-selections > $HOME/systemA_packages
It's also a good idea to take a copy of the /etc/apt/sources.list from systemA. Then, to apply the package selections of systemA to another system (which must be running on the same track, otherwise the package names may be different), copy over the file $HOME/systemA_packages to the new "clone" system and use:
  cat $HOME/systemA_packages | dpkg --set-selections
The above command will not actually install or remove anything. It just sets the selection state on the packages according to the list you provided from the original system. You then need to run dselect to actually download and install the packages. Before running dselect, remember to take a look at the /etc/apt/sources.list file from the systemA machine, to see if any of its sources need to be added to the sources.list of the clone machine, and run apt-get update before continuing, because dselect will only be able to download from sources that are configured.
The dselect tool will bring up a menu, and here you choose the "Install" option.

Reconfiguring packages

To "reconfigure" any given package (i.e. make the Debian package manager re-ask you all the package configuration questions):

  dpkg-reconfigure packagename

To reconfigure all packages manually all over again:

  dpkg --configure -a

There's also a tool called "debconf" for package reconfiguration.

Exploring aptitude

The aptitude package manager takes somewhat more time to learn. To install it along with its documentation, use:
apt-get install aptitude
apt-get install aptitude-doc-en
dpkg -L aptitude-doc-en|grep index.html
Then you can just open and read the manual from your local machine by pointing your browser to file:///usr/share/doc/aptitude/html/en/index.html

Choosing your Flavor

Some packages have a long history of alternative implementations, and you may feel most at home using a specific one of these all the time, rather than being unexpectedly exposed to a disconcerting "new features" (for example when your fingers wander accidentally to a key you didn't intend to press, and which previously had no effect).

For example, to choose which implementations of vi editor to use, run the following commands. The X cursor can also be changed using this method.
  sudo /usr/sbin/update-alternatives --list vi
  sudo /usr/sbin/update-alternatives --config vi
  sudo /usr/sbin/update-alternatives --list view
  sudo /usr/sbin/update-alternatives --config view
  sudo /usr/sbin/update-alternatives --list x-cursor-theme
  sudo /usr/sbin/update-alternatives --config x-cursor-theme

Choosing your display manager

In Debian, the default display manager is chosen by writing either /usr/bin/kdm or /usr/bin/gdm in the file:


Installing a Debian system via "Knoppix"

Knoppix is a convenient single-CD bootable distribution, based on Debian. To install Debian from a Knoppix CD, boot as usual from the Knoppix CD, then run the command:


This will bring up an easy-to-use installer, to guide you. After the install is completed, and Debian is installed on your hard drive, to update the resulting Debian installation to the latest available packages, do the following:
  apt-get update
  apt-get dist-upgrade

If you're behind a proxy server, first set the following in your environment, so that "apt" knows how to find its way to the Debian servers:
  export http_proxy="http://your-proxy.your-domain:80"

Installing Debian from the sarge-i386-netinst

Now that sarge is released (3.1r0 was released Monday, June 6th, 2005), the Debian Network install page gives links to the official images. If you previously did an install of sarge by following the instructions from this page, please remember to edit your /etc/apt/sources.list file to replace the word testing with the word stable, because sarge is now stable and "etch" is the name for the development version on the testing track.

Download the Debian Sarge Netinst and burn it to a CD. Boot from the Debian Sarge Netinst CD. The default setting is to install a 2.4 series kernel, which I'd recommend if you're installing Debian on a SparcStation 20 machine, but if you want to run your system with a 2.6 series kernel, then at the boot menu type:


Do the usual base Debian install from the CD, after which the system will reboot into the new (minimal) Debian. You can then continue the installation using an http source. It will ask you to select a country and a mirror. Let's select USA, and mirrors.kernel.org, and then it will ask if a proxy server is needed.

If you have another linux machine handy, instead of simply giving the address of your internet access proxy server (if you are using one), give the address of this handy machine, which you will intrepidly configure to serve as your very own Squid cache. This friendly Squid server will happily cache all of the packages you download from the debian mirror, so that if you need to install a second machine with Debian the install will run much more quickly, and place less load on the bandwidth of the mirror server. If you use the default Squid configuration, Squid runs on port 3128. So set the "proxy" server the Debian installer asks for to the following address, for example: http://your-machine.your-domain:3128 If you haven't set up a Squid server before, a quick guide to a suitable configuration (for this purpose of caching Debian packages) is described here: ExampleSquidConfiguration

In the Sarge installer, let's select a "Workstation" configuration, and let it install that. All of the packages it downloads (around 450MB of them) will be cached on your Squid server.

Note that the Sarge installer doesn't allow you to specify an IP address for your machine until after this step is complete. It depends on being able to get a dhcp leased IP address, so you'll need to set up your Squid server to allow access to the new leased IP while this phase of the install is running.

After getting the Workstation configuration installed, it's time to check if any updates have occurred in the meantime, since the installer might be old by the time you get this far, and fixes might already be available. To get the latest package summaries, run the command:

  apt-get update
  apt-get dist-upgrade

In my case, this also resulted in an update to the kernel package being installed, which fixed a bug (the aic7xxx SCSI host bus adapter driver wasn't recognising the aic7890 controller, and only the aic7880 controller was being seen). So after rebooting to the updated kernel, the aic7890 controller was recognised and the additional hard drive that was connected to it showed up. This was a bit of a messy situation, as you can imagine: all of the drive names got moved up by one letter. I corrected the /boot/grub/menu.lst and /etc/fstab to get things booting correctly again. The fixed kernel also has support for reiserfs, although you still needed to install the reiserfsprogs to create such filesystems:

  apt-get install reiserfsprogs

Note that the kernel installed by default by the Sarge installer is for the lowest common denominator of the intel family, the "i386". This kernel has the package name kernel-image-2.6.8-1-386. If your system is a Pentium III with multiple processors, then you'll need to manually install the kernel kernel-image-2.6.8-1-686-smp and update the /boot/grub/menu.lst file to boot this kernel. It's probably a good idea to also install the non-smp kernel, in case you need to remove a CPU at some time for whatever reason, although it seems that the Debian smp kernel is still be able to boot on a uniprocessor machine. Install the sources also, they're usually required for building modules and stuff. See the following guide to installing the kernel source for Debian.

Using make-kpkg is a convenient way of compiling your kernels for Debian. The Debian package kernel-package takes all the required steps for compiling a kernel so that the user need not remember the actual sub-steps involved. The Debian way allows you to keep multiple versions of kernel images on the same machine with little effort. Even multiple flavors of the same kernel version can easily be accommodated.

Other kernel module packages are also hooked into the Debian way of dealing with kernels so that you can simply compile them as part of the kernel compile process. This includes the Debian packages pcmcia-source and alsa-source. Such modules generally rely on the particular kernel version. Debian also has the nice feature of keeping the configuration file for each kernel image in /boot, with a name such as /boot/config-2.6.8-1-686, for example.

Some of the things I needed to install manually are on this page, which never seems to be quite finished: DebianSargeNetinstManuallyInstalledPackages

Installing "Testing" from Netinst

To install Debian from the Testing track (currently called "Etch") rather than from the Stable track, here is where you can find info on the testing Netinst CD.

Using the Testing installer may be the best approach for getting Debian installed on newer hardware, especially in the case where the Sarge installer doesn't have the network driver to support your network card. For example on the HP Compaq dc7600, the network chip is a Broadcom Corporation NetXtreme BCM5752 Gigabit Ethernet PCI Express, which is only recognised by the Testing installer.

Alsa Sound Configuration in Debian

To get alsa sound working, use /usr/sbin/alsaconf. For example, on a Dell Precision 410 system, tell it to probe for ISA sound cards, and select only the cs4236 from the list presented (use spacebar to remove the selection from all of the other cards listed). Continue, and alsaconf will then prompt you on whether it should add the sound card module aliases and parameters to the file /etc/modprobe.d/sound. Give it the OK, and the result should look like the following:

  options snd  device_mode=0660
  alias snd-card-0 snd-cs4236
  alias sound-slot-0 snd-cs4236
  options snd-cs4236 port=0x530 cport=0x538 isapnp=0 dma1=1 dma2=0 irq=5
  install snd-cs4236 /sbin/modprobe --ignore-install snd-cs4236 && /usr/lib/alsa/modprobe-post-install snd-cs4236

It may also be necessary to add your user to the audio group, which owns /dev/dsp, either using vigr or as follows:

  /usr/sbin/usermod -G audio username

Then use alsamixer to set the master volume control to 60% and the PCM volume control to 100%, and you'll hear sounds play when you open a new terminal window, for example. For fullscreen video playback, we need Xvideo support. To check if the support is enabled, use xvinfo.

Video Editing Tools in Debian

Debian kino package "suggests" mjpegtools, but there doesn't appear to be such a Debian package. It appears that the license precludes mjpegtools from being included.

For now, such tools are available as Debian packages in Marillat's repository.

Note that this repository uses the FTP protocol rather than HTTP, so it won't be accessible via the example Squid configuration described earlier.

If you are trying to follow the development of transcode, you may need to build to build mjpegtools yourself. It seems to be simplest to build mjpegtools from the tarball rather than from the mjpeg CVS.

What's the story with acroread in Debian?

What, you can't live with xpdf, you want to use a buggy non-Free Software (proprietary) product that leaks information? Well, this section is for you. According to Mimos Berhad's Knoppix User's Guide, quite a few convenient tools are available as Debian packages in Marillat's repository, and acroread is one of them.

It's simple enough to use dpkg directly to install acroread as follows:
  wget ftp://ftp.nerim.net/debian-marillat/dists/stable/main/binary-i386/acroread-debian-files_0.0.8_all.deb
  wget ftp://ftp.nerim.net/debian-marillat/dists/testing/main/binary-i386/acroread_5.10-sarge0.1_i386.deb
  dpkg -i acroread-debian-files_0.0.8_all.deb acroread_5.10-sarge0.1_i386.deb

To annotate PDF files, give Johannes Hofmann's flpsed a try.

Video playback in Debian

The Debian Stable track has a convenient media player in the package vlc. Install it preferably by installing the wxvlc package, which provides the frontend. VLC is the VideoLAN project's media player. It plays back MPEG, MPEG2, MPEG4, xvid, DivX, MOV, WMV, QuickTime, mp3, Ogg/Vorbis files, DVDs, VCDs, and multimedia streams from various network sources.

  apt-get install wxvlc

If your system is somewhat older and slower, mplayer will squeeze the last drop of performance from your system. Install mplayer-nogui from Marillat's repository to get mplayer.

Video Playback Considerations

The package libdvdread3 "suggests" libdvdcss2, but the DMCA precludes it from being provided as a binary Debian package. You may of course build libdvdcss from the libdvdcss 1.2.8 sources, but there is also a convenient Deb package provided, along with a Deb dev package, which can be installed using:

  wget http://download.videolan.org/pub/libdvdcss/1.2.8/deb/libdvdcss2_1.2.8-1_i386.deb
  wget http://download.videolan.org/pub/libdvdcss/1.2.8/deb/libdvdcss2-dev_1.2.8-1_i386.deb
  dpkg -i libdvdcss2_1.2.8-1_i386.deb
  dpkg -i libdvdcss2-dev_1.2.8-1_i386.deb

The libdvdcss library is loaded dynamically by libdvdread, when libdvdread encounters a DVD mastered using the content scrambling system (CSS). For more info, see the homepage of libdvdcss.

X11 forwarding over OpenSSH

Debian disables X11 forwarding over ssh session by default, probably because it's not really all that secure. If you've become addicted to using X11 forwarding (from having it turned on in many RPM-based distributions), you can edit the file /etc/ssh/sshd_config and change the setting for X11Forwarding to yes as follows:

  X11Forwarding yes
Then, restart the ssh daemon using:
  invoke-rc.d ssh restart

Thereafter, you'll be able to use the -X flag when you login over ssh, so that when you invoke X11 applications, they'll be displayed on your local server.

Installing Oracle 10g on Debian

Printing in Debian

If you have configured CUPS in the past, you may be a little leery of any guide purporting to explain how to do it in less than a page. You would be right. Even though CUPS can be tricky to set up, it is worth the effort. Hopefully you will be encouraged to hear that setting up CUPS seems to be somewhat easier on Debian than on many RPM-based distributions. Anyway, let us enter the fray, intrepidly installing the CUPS system, the CUPS client and the ESP GhostScript packages using:

  apt-get install cupsys
  apt-get install cupsys-client
  apt-get install gs-esp

If you would also like CUPS's BSD lpr interface to work, for the benefit of applications that expect to print only to such an interface, then you'll need to install the package cupsys-bsd, which is the lpr-emulation front-end to CUPS:
  apt-get install cupsys-bsd

The cupsys-bsd default setup is such that it expects to read lpr-style printer info from /etc/printcap, whereas the default Printcap entry in /etc/cups/cups.conf causes the CUPS administration routines to write lpr printer info to /var/run/cups/printcap. Let's edit the CUPS configuration file /etc/cups/cupsd.conf and change the setting for Printcap from:
Printcap /var/run/cups/printcap
Printcap /etc/printcap

To access the CUPS web aministration interface, add your user to the lpadmin group, either using vigr or as follows:
  /usr/sbin/usermod -G lpadmin username

Then go to the CUPS web administration interface at port 631:

If you need to add an entry to /etc/cups/passwd.md5, proceed as follows:
touch /etc/cups/passwd.md5
lppasswd -a username

The passwd.md5 will only be used by CUPS for authentication if the /etc/cups/cupsd.conf configuration file has the following settings. The default Debian CUPS configuration file uses AuthType Basic and AuthClass User, thus allowing access to any user who is a member of the lpadmin group.
  AuthType BasicDigest
  AuthClass Group
  AuthGroupName lpadmin

To add (for example) a HP LaserJet 8100 printer, navigate the interface as follows: Administration -> Add Printer -> AppSocket/HP DirectJet

Enter the following:
Device URI: socket://printer_hostname:9100
      Make: HP
     Model: HP LaserJet Series CUPS v1.1
Save the printer. Now you still need to configure the printer in the CUPS interface. Click on Printers, and this will bring up a page with an icon for your printer. Click on the Configure Printer button, and in the General settings, make the following choices:
   Double-Sided Printing: Long Edge (standard)
              Media Size: US Letter
            Media Source: Tray 3
The reason for choosing the Media Size as US Letter is that if you use the default of A4, this will result in the printer attempting to print from the manual feed tray (Tray 1). This is because all of the supplies inside the printer are usually of size US Letter (this may be different if your printer is not in the USA).

In addition, for printing from xpdf, you'll need to configure the page size as letter instead of "a4" by editing /etc/papersize to make the change:
  sudo echo "letter" > /etc/papersize

Also, before saving with Double-Sided Printing setting, you need to enable Duplex Printing in the configuration slightly lower down on the page.

For configuring Mozilla to use CUPS rather than lpr, select File -> Print from the menu, then press the Properties... button and replace:



The above can also be used instead of lpr in the xpdf print dialog. Remember before printing from xpdf, to edit /etc/papersize to change the a4 to letter.

What, still no printout from Debian?

First of all, test whether network access to the printer is indeed working. For this, you can use telnet printer_hostname 9100 and just type in some text and close the telnet session. This should print out the text. Some printers even run a small web server, which you can connect to by pointing your browser to

Using CUPS, if you print a test page to the printer but nothing comes out, it may be because you didn't install the ESP GhostScript package gs-esp. If this is the case, you may see an error message in the CUPS log file /var/log/cups/error_log as follows:
Unable to convert file 0 to printable format for job 1!

If you see this message, install ESP GhostScript package and restart CUPS using:
  apt-get install gs-esp
  invoke-rc.d cupsys restart

How Can I Track Down Printing Problems using CUPS?

For getting familiar with CUPS, the best place to start is of course the homepage for CUPS. Here, I'll just mention the first thing they suggest doing if you encounter any printing problems: change the setting for the "LogLevel" parameter to "debug" in the CUPS configuration file /etc/cups/cupsd.conf as follows:
  LogLevel debug

After doing this, restart the cupsd process using:

  invoke-rc.d cupsys restart

The following file will contain a detailed log of everything that is reported by the scheduler and print filters:

Changing your network configuration

The configuration file for the network interfaces on Debian is:
To use dhcp on an interface, the file should contain:
  # This file describes the network interfaces available on your system
  # and how to activate them. For more information, see interfaces(5).

  # The loopback network interface
  auto lo
  iface lo inet loopback

  # The primary network interface
  auto eth0
  iface eth0 inet dhcp
To use static addresses on two different interfaces, use for example:
  # This file describes the network interfaces available on your system
  # and how to activate them. For more information, see interfaces(5).

  # The loopback network interface
  auto lo
  iface lo inet loopback

  # The primary network interface
  auto eth0
  iface eth0 inet static
  auto eth1
  iface eth1 inet static

Configuring the NFS automounter

If you work in an environment where you frequently make use of a lot of NFS servers, you may prefer to use the automounter from the autofs package. To configure it so that it automatically mounts a filesystem (for example, shire) which has been exported to you from a remote server machine (for example, frodo) when you type cd /net/frodo/shire, you'll need to uncomment the following line from the file /etc/auto.master

/net    /etc/auto.net
Then get the automounter to re-read its configuration file, as follows:
  invoke-rc.d autofs reload
The above command will cause the automounter to check the current /etc/auto.master map against its running daemons, then kill those daemons whose entries have changed, as well as start daemons for new or changed entries (which is what we have done here, by adding a new entry to the /etc/auto.master map).

Run to Catch up With the Sun...

If your system is frequently connected to the network (as Debian systems tend to be), then it may be convenient to set and synchronize the system time by connecting to a Network Time Server using the NTP protocol. To set this up, install the packages:
  apt-get install ntpdate
  apt-get install ntp
  apt-get install ntp-doc
  apt-get install ntp-simple

If you have direct access to the internet, then this will be sufficent, but you may prefer to access a local NTP server rather than fetching time from the internet. To do this, you'll need to edit the file /etc/default/ntpdate to modify the setting for NTPSERVERS, and also edit the file /etc/ntp.conf to replace server pool.ntp.org with an entry containing the IP address of your local NTP server. At some sites, you may find that each of the subnet routers is configured as an NTP server.

To set the new system date and time, and start the NTP daemon process to keep it in sync from then on, do:
  invoke-rc.d ntpdate restart
  invoke-rc.d ntp-server restart

If you ever find yourself in an unexpected and unfamiliar timezone, you can use the tzconfig program to set the timezone correctly (unless of course you are physically in the wrong place, in which case tzconfig will only add to your disorientation).

Corkscrew: OpenSSH via your HTTP proxy

The package corkscrew maintained by Pat Padgett is a tool for tunneling OpenSSH through HTTP proxies. The concepts are tricky to describe in the abstract, so an example is in order. First install the package:
  apt-get install corkscrew
Let's say there's a machine tty.freeshell.org that you would like to connect to over OpenSSH on port 22, and your HTTP proxy is called your-proxy.your-domain and is listening on port 80. Adding the following two lines to your $HOME/.ssh/config file should be sufficient to get things going:
Host sdf
        ProxyCommand /usr/bin/corkscrew your-proxy.your-domain 80 tty.freeshell.org 22
After that, you'll be able to establish an OpenSSH session using:
ssh username@sdf

Cryptsetup: using device mapper's dm-crypt for encrypting your filesystem

If you have been using cryptoloop for filesystem encryption in the past, you may have noticed that since kernel 2.6.4 there's a warning with the BLK_DEV_CRYPTLOOP configuration option that says:
  WARNING: This device is not safe for journaled file systems like
  ext3 or Reiserfs. Please use the Device Mapper crypto module
  instead, which can be configured to be on-disk compatible with the
  cryptoloop device.
So how do we use the Device Mapper as the warning suggests? The place to start is Christophe Saout's dm-crypt page. The wikipedia page for dm-crypt is also a good reference. For Debian, this guide or this guide go into a lot of detail.

When using disk encryption, remember that your DRAM is not as volatile as you might have thought.

Essentially, the cryptsetup utility hides all of the details of needing to understand the Device Mapper's dm-crypt syntax, although it's good to know you can always carry out the steps manually if necessary, using only the dmsetup utility. I'll only quickly show the commands to create an encrypted filesystem within a plain file:

  apt-get install cryptsetup
  modprobe dm_mod
  modprobe loop max_loop=32
  dd if=/dev/urandom of=$HOME/cryptfile2 bs=1M count=100 
  losetup /dev/loop2 $HOME/cryptfile2
  cryptsetup -y -c aes -h ripemd160 -s 256 create volume2 /dev/loop2
  mke2fs /dev/mapper/volume2
  mount -t ext2 /dev/mapper/volume2 /mnt/machine/volume2
To unmount the filesystem, proceed as follows:
  umount /mnt/machine/volume2  && \
  cryptsetup remove volume2 && \
  losetup -d /dev/loop2
To mount the filesystem again, use:
  modprobe dm_mod
  modprobe loop max_loop=32
  losetup /dev/loop2 $HOME/cryptfile2
  cryptsetup -y -c aes -h ripemd160 -s 256 create volume2 /dev/loop2
  mount -t ext2 /dev/mapper/volume2 /mnt/machine/volume2

Note: File-backed loop devices can't be used with journaling file systems. Only device-backed loops guarantee that writes will reach the disk platters in the order required by a journaling file system (write caching must be disabled on the disk drive, also). With file-backed loop devices, the correct write ordering may extend only to the page cache (which resides in RAM) of the underlying file system. The linux VM can then write such pages to disk in any order it wishes, potentially breaking the write order expectations of the journaling file system. Another problem is that file-backed loops may deadlock under some kernel and file system combinations. So, if you can choose between device-backed and file-backed, choose device backed even if it means that you have to re-partition your disks.

If you need to move your data from a system which doesn't have cryptsetup, but does have Device Mapper, you can build cryptsetup from the CVS as described on the dm-crypt wiki using:
  # In the following, you can remove ";proxy=your-proxy;proxyport=80" if you're connecting directly to the internet.
  cvs -d ':pserver;proxy=your-proxy;proxyport=80:cvs@cvs.saout.de:/cvsroot/saout' login
  # Password is: cvs
  cvs -z3 -d ':pserver;proxy=your-proxy;proxyport=80:cvs@cvs.saout.de:/cvsroot/saout' co cryptsetup
  cd cryptsetup
  su -c "make install"
For the future, loop-AES gives better performance than dm-crypt. For Debian, this guide and this guide are a good start.

Additional Debian Resources

Once you get more familiar with Debian, have a look into the following resources. Happy trails.


This guide is thanks to the patient explanations from:

Rick Moen (rick@linuxmafia.com), Daniel Gimpelevich and Calvin Wong.