LINUX NEWS
Resources & Links From CramSession.com
Thursday, December 20, 2001TABLE OF CONTENTS
1) Sean’s Notes
2) Linux News
Mandrake 8.1: An Easy Install?
Just What's Up With Lindows?
Perl is 14 Years Old
Sale On Linux Training3) Linux Resources
Test Your Scripts!
Understanding Rootkits
Dual Booting Linux and Windows 2000 on Large Hard Disks
Document Your Code
\*BSD Installation4) App o’ the Week
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1) Sean's Notes
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One of the selling points of Linux is that you have the
source to the complete operating system. That's great, but
unless you're a kernel hacker, why would you need the source?
With a basic knowledge of where stuff sits within the kernel
tree, you can easily answer questions like what driver to use,
or find out if a device is supported.
The kernel sources usually live in /usr/src/linux,
/usr/src/linux-2.4, or something close. On my system, the
list of directories is as follows:
arch
Documentation
drivers
fs
include
init
ipc
kernel
lib
mm
net
scripts
The arch directory contains code specific to your architecture
(i.e. processor), such as how to boot, or manage memory. Not
very interesting to us now.
"Documentation" is full of good stuff. Pretty much every
section of the kernel has at least something in there.
"serial-console.txt" is a helpful document on how to set up
your console on a serial port, so that you don't need a monitor
or keyboard. The "fs" directory has basic information on every
file system supported, such as where to get the userland tools
to manage them, and the status of the code. "networking" has
information on the protocols supported, network drivers, and
how to use them. Ditto "usb" and "sound".
The next top level directory of interest is "drivers". Here
is where you'll find most of the support for devices. It's
laid out in a haphazard manner, so it may take some digging.
Our first stop in this part of the tour is the "net" directory,
which contains all the device drivers for network cards.
Let's say you've got a DE202 network card, and want to figure
out the driver. Chances are, it's part of a generic driver
for part of the whole family, so it won't have a de202.c file
sitting around:
<div class="highlight"><pre><code class="bash"><span class="o">[</span>root@bob net<span class="o">]</span><span class="c"># grep "DE202" *.c</span>
depca.c: DE202 Turbo <span class="o">(</span>TP BNC<span class="o">)</span>
depca.c: The driver has been tested on DE100, DE200 and DE202 cards
depca.c: Digital Equipment corporation, 1991, Pub. <span class="c">#EK-DE202-OM.001</span>
depca.c: 0.31 4-feb-94 Added DE202 recognition.
depca.c: <span class="s2">"DE200"</span>,<span class="s2">"DE201"</span>,<span class="s2">"DE202"</span>,<span class="se">\</span>
</code></pre></div>
Looks like depca.c is the file that implements the driver for
the DE202 network card. If you edit the file, you'll see
instructions on what settings the driver supports, limitations
(such as multiple cards), and sometimes some hints on getting
the card to go. More often than not, the name of the .c file
is the name of the driver. We can verify this by looking for
the object file (depca.o) that will be the driver:
\[root@bob net]# locate depca.o
/lib/modules/2.4.7-10/kernel/drivers/net/depca.o
Yep, there you go. So to get that old DE202 card (and I've
got a bunch!) working, you'd run:
# modprobe depca
or add something like:
alias eth0 depca
to /etc/modules.conf
Under drivers/usb, you'll find a list of drivers for USB
devices. Since Linux is relatively new to the USB arena,
you'd be wise to check here for support before buying that
expensive device. (A search on google.com would also be a
good idea, someone may have written a driver that hasn't yet
made it into the kernel.)
drivers/scsi has all the SCSI card drivers, and a lot of
README files with helpful advice.
Back to the top level, I'll skip all the way down to "net"
(most of the stuff in between is the kernel itself). This
contains all the network protocols. A question was asked on
the Network+ board this week "Where is TCP/IP implemented in
Linux?" "net/ipv4" would be the answer to that question.
You'll also find the implementation of Ethernet (not to be
confused with the Ethernet drivers we saw earlier), x.25 (wow)
ipv6, ipx, decnet (ouch!), 802.1D bridging, bluetooth, ATM,
and a lot more.
So, really, the kernel source is nothing to be afraid of. The
Documentation directory has a wealth of practical information
about how the system operates. "drivers" contains all the
hardware drivers the operating system comes with, and "net"
has information on all the network protocols.
You don't have to be a C programmer to make use of it, either.
The grep technique above works well, and source code comments
can be read by anyone. In particular, ISA cards (do they
still exist?) can be configured with multiple IRQs, but only
the driver source will tell you which one the driver will be
looking for. If you're seeing strange error messages, grepping
around can help you determine the source, and the likely cause.
Source isn't only for programmers anymore. It can now be a
valuable tool for the systems administrator.
Happy holidays to everyone...and of course, long live the
Penguin!
Sean
mailto:swalberg@cramsession.com
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2) Linux News
-------------------------
-------------------------------
Mandrake 8.1: An Easy Install?
-------------------------------
This article focuses on the installation of Mandrake, SuSE,
Red Hat, and Win XP. The author's system has a couple of
extras, so it's not surprising that some of the packages
had some trouble. Mandrake came out on top--a few minor
hiccups, but a clear winner.
http://www.newsforge.com/article.pl?sid/12/18/1410254
-----------------------------
Just What's Up With Lindows?
-----------------------------
The more I think about Lindows, the more I have to wonder
about its viability, or even if it will ever be completed.
I'm not the only one; desktoplinux.com has written a very
good article on the topic -- is Lindows a good thing?
http://desktoplinux.com/articles/AT2152579590.html
---------------------
Perl is 14 Years Old
---------------------
Wow. I didn't have a clue that it's been around so long. I
got my start around five years ago, and thought the language
was pretty new. There is a lot of Internet history in this
document too, a very interesting read if you're interested
in seeing how the Internet and Perl have evolved together.
http://history.perl.org/PerlTimeline.html
-----------------------
Sale On Linux Training
-----------------------
Judging by the amount of people on the Cramsession boards
asking for Linux training locations, this $200 discount on
Red Hat courses will go over well. If you're aware of other
training centers doing Linux courses, please let me know and
I'll pass it along to everyone else.
http://www.redhat.com/training/skills_offer.html
-------------------------
3) Linux Resources
-------------------------
-------------------
Test Your Scripts!
-------------------
I can't count the number of times I've made a change to one
part of a script I wrote, which broke another part. I know
I should use automated tests, but until I saw this article,
I thought it would be too much trouble.
http://www.perl.com/pub/a/2001/12/04/testing.html
-----------------------
Understanding Rootkits
-----------------------
A rootkit is a package a cracker can leave on your system
that ensures an easy way back in. Rootkits will replace
some of your system binaries, or even load themselves into
the kernel. Luckily, there are tools out there to detect
unauthorized changes, and some simple precautions you can
follow.
http://linux.oreillynet.com/pub/a/linux/2001/12/14/rootkit.html
--------------------------------------------------------
Dual-Booting Linux and Windows 2000 on Large Hard Disks
--------------------------------------------------------
With a dual-boot system, you can have multiple operating
systems run off the same hard drive. There are limitations,
though, and things you have to keep in mind. This article
is a great set of instructions on how to get Linux and Win2k
to live together happily.
http://www.enterprisedt.com/publications/dual_boot.html
-------------------
Document Your Code
-------------------
One feature of Perl that I have been making use of lately is
POD, short for "Plain Old Documentation". It's nothing more
than specially formatted comments, with the added feature that
your source code can be run through some filters to generate
the documentation. It's a lot better than trying to remember
how to call a module you wrote a year ago!
http://www.linuxgazette.com/issue73/spiel.html
-------------------
\*BSD Installation
-------------------
Even though this is a Linux newsletter, there are a lot of
other Unix flavors out there that deserve the odd mention.
The popular free BSDs (Free, Open, and Net) are compared in
this multi-part series, focusing on the installation
procedures.
http://bsdfreak.org/article_2001_11_24_4013.html
-------------------------
4) App o' the week
-------------------------
Users are complaining your web site is too slow, but how can
you measure it?
"PasTmon is an Open Source passive network application
response time monitor, utilizing packet capture (via libpcap),
tracking sessions, maintaining transaction state, and
collecting metrics of server/network response times, segment
size negotiation, and TCP window size advertisements.
The goal of the PasTmon project is to provide an engine to
measure application service levels from the perspective of
perceivable user response times.
Mechanisms are provided for data summarization/reduction and
import into a PostgreSQL database.
A web PHP4-based front-end to example R statistical graphics
is provided."
http://pastmon.sourceforge.net/
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(C) 2001 BrainBuzz.com, Inc. All Rights Reserved.
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