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Debian Linux

Happy Birthday Debian Linux

Debian was first announced on 16 August 1993, by Ian Murdock, who was then a student at Purdue University. The latest stable release of Debian is 4.0. Debian is well known for following the Unix and free software philosophies. All code names of Debian releases are names of characters from the film Toy Story - Buzz, Rex, Hamm, Woody, Sarge and Etch etc.

According to Spanish university study - Debian's 283 million lines of source code would cost US $10 billion to develop by proprietary means.

Debian is also well known for stability and many new distros based upon Debian such as Ubuntu. Today, Debian turns 15 - HAPPY BIRTHDAY!!!

Debian Linux Kernel v2.6.18 Local / Remote Packages Fix Overflow Conditions Bug

There are new two vulnerabilities have been discovered in the Debian Linux kernel that may lead to a denial of service or arbitrary code execution. The Common Vulnerabilities and Exposures project identifies the following problems:
=> Package : linux-2.6
=> Vulnerability : heap overflow
=> Problem type : local/remote
=> Debian-specific: no
=> CVE Id(s) : CVE-2008-1673 CVE-2008-2358

How do I fix this problem

Type the following command to update the internal database and to install corrected packages:
# apt-get update
# apt-get upgrade
# reboot

CVE-2008-0595: Linux dbus packages fix privilege escalation

Debian Linux has issued a security update for its dbus package which is simple interprocess messaging system for X11 and other software parts under Linux. There is privilege escalation bug i.e. it performs insufficient validation of security policies, which might allow local privilege escalation:
=> Package : dbus
=> Vulnerability : programming error
=> Problem type : local
=> Debian-specific: no
=> CVE Id(s) : CVE-2008-0595

How do I fix this bug

Type the following two commands to update the internal database, followed by actual installation of corrected package:
# apt-get update
# apt-get upgrade

Shell Script: Create Linux Bootable USB Sticks

This may come handy, from the project page:

Mk-boot-usb is a perl script to create multiple-bootable usb sticks (usb keys / usb flash drives). It wipes out an entire usb stick, partitions it, creates file systems on it, installs grub, and installs a minimal linux on it. Mk-boot-usb is meant to speed up and lower the barrier of entry for creating bootable usb sticks. The usb stick will immediately become bootable (using the minimal linux), and more useful distributions can then be installed into other partitions manually simply by (1) copying any Live CD into each partition (2) modifying grub's configuration file.

=> Mk-boot-usb: a Script to Create Multiple-Bootable USB Sticks

Related: How to Create Bootable Linux CD

Can I boot My Linux Server from iSCSI or SAN or NAS network attached storage?

My previous article related to iSCSI storage and NAS storage brought a couple of questions. An interesting question from my mail bag:

I've 5 Debian Linux servers with HP SAN box. Should I boot from SAN?

No, use centralized network storage for shared data or high availability configuration only. Technically you can boot and configure system. However I don't recommend booting from SAN or any other central server until and unless you need diskless nodes:

[a] Use local storage - Always use local storage for /boot and / (root) filesystem

[b] Keep it simply - Booting from SAN volumes is complicated procedure. Most operating systems are not designed for this kind of configuration. You need to modify scripts and booting procedure.

[c] SAN booting support - Your SAN vendor must support platform booting a Linux server. You need to configure HBA and SAN according to vendor specification. You must totally depend upon SAN vendor for drivers and firmware (HBA Bios) to get thing work properly. General principle - don't put all your eggs in one basket err one vendor ;)

[d] Other factors - Proper fiber channel topology must be used. Make sure Multipathing and redundant SAN links are used. The boot disk LUN is dedicated to a single host. etc

As you can see, complications started to increases, hence I don't recommend booting from SAN.

How to: Install and Setup XEN Virtualization Software on CentOS Linux 5

One of our regular reader asks:

I'm using CentOS Linux 5 server. How do I set up Xen on Linux ? How do I install guest VPS oses such as Fedora or Windows 2000 or Debian Linux inside XEN?

Xen is a free open source software virtual machine monitor for Intel / PowerPC architectures. It is software that runs on a host operating system and allows several guest operating systems to be run on top of the host on the same computer hardware at the same time (just like VMWare software). Luckily Installing and managing XEN is quite easy under CentOS 5 Linux.

Login as the root and type the following commands:
# yum install xen virt-manager kernel-xen
# chkconfig xend on
# reboot

Make sure you boot CentOS server using XEN kernel.

How do I install NetBSD / any Linux distro / Windows 2000 inside XEN?

Simply use gui tool called virt-manager:
# virt-manager &

CentOS XEN Virtual machine manager

CentOS XEN Virtual machine manager

Now just follow on screen instructions to setup new guest operating systems (VPS oses). virt-manager is Xen Management Consoles software. It can perform the common tasks of administering a Xen host such as configuring, starting, monitoring and stopping of Xen guests oses. Please note that above instructions also works on

  • RHEL 5
  • Fedora Linux 7

Installing CentOS 5.3 guest using the Internet

virt-install is a command line tool for provisioning new virtual machines using the "libvirt" hypervisor management library. Type the following command to install CentOS v5.3 64 bit as guest operating system in /vm:
# mkdir /vm
If you are using SELinux, enter:
# semanage fcontext -a -t xen_image_t "/vm(/.*)?"
# restorecon -R /vm
# ls -dZ /vm

Above will provide security context of Xen images. Finally, install CentOS 5.3 using the Internet mirror:
# virt-install \
--paravirt \
--name webserver01 \
--ram 512 \
--file /vm/webserver.nixcraft.com.img \
--file-size 10 \
--nographics \
--location http://mirrors.kernel.org/centos/5.3/os/x86_64/

Above will CentOS as a paravirtualized Xen guest, with 512 MB of RAM, a 10 GB of disk, and from a web server, in text-only mode. You need to just follow on screen instructions.

Fig.01: Centos Xen Virtualization Installation

Fig.01: Centos Xen Virtualization Installation

Once installed you can use xm command to list, start, stop and manage xen vps:
# xen list
Attach console to domain / guest called webserver01:
# xm console webserver01
See xm command cheat sheet.

Installing CentOS 5.3 guest using DVD

Install a CentOS guest, using LVM partition, virtual networking, booting from the host CDROM, using VNC server/viewer (insert DVD into drive):
# virt-install \
--connect qemu:///system \
--name mailserver
--ram 500 \
--file /dev/HostVG/mailserver.cyberciti.biz \
--network network:default \
--accelerate \
--vnc \
--cdrom /dev/cdrom

Note you need qemu and virt-viewer installed on the host system.

Installing Fedora guest using DVD iso image stored on hard disk

Install a Fedora Linux, with a real partition (/dev/sdc), using a local DVD ISO image:
# virt-install \
--name www2 \
--ram 1000 \
--file /dev/sdc \
--network bridge:eth1 \
--cdrom /tmp/fedorabootdvd.iso

Further readings:

Hardware and software failures are part of life. And that is why you need to have a backup plan. I have already written about backing up files and MySQL databases. There is no need to backup all installed binaries and software programs. The following tip will not just save your time, but both Debian/Ubuntu and CentOS/Fedora/RHEL based distro can be updated and restored when required.
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