A Brief Word about Linux Distributions


As stated earlier, we will be focusing, for the most part, on the Red Hat 8.0 Linux platform for all of our examples and walk-throughs. Many of you might not use Red Hat as your preferred distribution, so we would like to stop and acknowledge a few of the more prevalent versions out there and some variations you will find in the documentation you are about to read. We are going to look at just a few of the distros not based on the Red Hat Package Manager (RPM) management system. The following distributions rely on either source-based distribution, or proprietary methods of package management. Other releases that use RPM as their system of choice include SuSE, Mandrake, Turbolinux, and Conectiva.

Debian

Debian GNU/Linux (currently in stable version 3.0) has been around forever and is known to many as the most secure and stable version of Linux available. apt-get, the package management system on Debian, is second to none in terms of ease of use. The apt-get syntax goes something like this

  • apt-get install packagename (where packagename is the name of the software package) installs new packages. These packages can come from the Debian CD, an NFS share, or straight from the Debian mirrors on the Internet, and download and install in one simple step.

  • apt-get remove packagename uninstalls software already on the machine.

Slackware

Slackware Linux (currently in stable version 9.0) is a favorite among hardcore Linux users, and understandably so. The support base for it is huge, and the system itself is stable, fast, and secure. Although this distribution is not for the faint of heart, we recommend it to anyone ready for the challenge. Slackware Linux also has a package management system based on the compile-from-source tarball model. Its packages can be easily identified by their .tgz extension. There is a built-in utility called pkgtool that allows for easy package management, or you can simply add/remove/edit packages right from the command line. For example:

  • installpkg packagename will install the package you choose onto your system.

  • removepkg packagename will uninstall the package of your choice.

  • upgradepkg oldpackage%newpackage is the quick-and-dirty way to upgrade your packages on-the-fly.

One other thing we would like to point out about the Slackware distro is the rpm2targz utility. This program converts RPM files to a format usable on a system without RPMs. The syntax for rpm2targz is:

rpm2targz packagename.rpm. 

Gentoo

Gentoo Linux (currently in pre-release 1.4rc3) is an interesting distribution unlike any other available today. The only thing close that we are aware of is the Linux From Scratch (LFS) project. The idea behind Gentoo Linux is to provide users with a minimal (45.3MB according to their FTP mirrors) CD that you boot to and connect to the Internet to download the rest of the distribution. Gentoo then builds the entire OS to be optimized for your specific hardware. For package management, Gentoo uses the emerge system. emerge works much like apt-get, but is slower because it builds and compiles each package optimized for your system. The way in which emerge works is fairly straightforward: It downloads the source code for the software package you request, compiles it, and installs it into the running system. Like we said, it's a close cousin of apt-get, and the only noticeable difference is that apt-get doesn't compile the software it downloads. Emerge, like apt-get, pulls its software index from what is called the Portage tree. The Portage tree is basically a database containing information about every package ready to run on Gentoo Linux. To give you an idea of how emerge works, including syntax, we have included an example shown next. In this example, we will download and install the Snort package. (Sounds like a proper choice considering the material we are going over, doesn't it?)

First, we will find out if Snort is available in the Portage tree by querying it with the following syntax:

emerge –p snort

This tells emerge that we want to pretend to install Snort (you guessed it… –p means pretend). emerge will then present us with a list of software that will be downloaded to satisfy Snort and its dependencies. It will look something like this (this is not actual output… it's fictitious, but you get the idea):

Calculating dependencies......... done! [ebuild   U] sys-libs/lib-1.1.3-r2 to / [ebuild   U] sys-libs/glib_not-1.2.9 to / [ebuild N  ] snort-libs/fakelibs-1-a2 to / [ebuild N  ] snort-base/snort-1.9.1 to /

If we are satisfied with the output, simply enter the command emerge snort, and Gentoo will gladly install Snort for you. To uninstall a package, the command is unmerge snort. Enough said—emerge is that simple, and an excellent package tool.




The Best Damn Firewall Book Period
The Best Damn Firewall Book Period
ISBN: 1931836906
EAN: 2147483647
Year: 2003
Pages: 240

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