Hackszine.com: Linux Archives

Archive: Linux

Page 4 of 6 << 1 2 3 4 5 6 >>

December 16, 2007

HOWTO - DIY radio modem

Eric Seifert sent in some information on creating a home brew radio modem using a standard PC sound card, an iPod FM transmitter, and an FM radio. He has his current revision working at 9600 BAUD for distances in the neighborhood of hundreds of feet.

The sending side outputs an amplitude encoded data stream to the sound card, which is connected to the FM transmitter. On the receiving end, an FM radio receives the transmission, and outputs it to the receiving soundcard's line-in, where it is then decoded. The hardware set up is extremely simple. It's the software for reliably encoding and decoding the data (and handling error conditions) that's the tricky part.

Eric released some example encoding/decoding software on his site, so you can start with that and take a swing at improving its error handling ability. You'll need a Linux box with the ALSA and SDL libraries to compile it.

Radio Modem - Link

December 12, 2007

XO laptops starting to arrive

Xo Intro V2

Doug Johnson reports on what may be the first G1G1 XO laptop to arrive:

The small box included the computer, the power adaptor, 2 sheets of paper with minimal instructions, and the battery which had to be installed. The package was shipped FedEx from Libertyville IL on Dec 7 and arrived on my doorstep at exactly 4:30PM yesterday, Dec 11. I had no advance notice and did not need to sign for the package.

Doug fields some questions from visitors to his site, and has a few pictures up there. Let us know if you got one, too! [via] Link

December 9, 2007

HOWTO run Ubuntu off a USB drive on the Asus EEE

Ubuntu on the EEE PC

C. K. Sample III has posted a comprehensive HOWTO on running Ubuntu on the Asus EEE PC... a fully-functional install on a USB drive:

I've been combing over various guides and instructions online for installing Ubuntu on the Asus Eee PC, and I ran into a few kinks along the way since I don't have a USB CD-ROM to install from and opted for a USB flash drive instead, so I thought I'd write the process out in this post in the hopes of helping those of you out there who are thinking about taking the plunge, but unsure of how it's going to work. All of this information is available elsewhere, but I found it somewhat scattered, so I'm documenting it all here for my future self.

This is a great way to embiggen the amount of disk space at your disposal. The next step would be to get that USB drive into the inside of the EEE PC or find a really low-profile USB drive that you could affix with some hot glue so it doesn't come loose too easily.

Ubuntu on the Asus Eee PC: Part 1 (or How to run a functional Ubuntu install off a USB drive) - Link

November 27, 2007

HOWTO run the XO laptop emulator on Ubuntu Gutsy Gibbon

Tom Hoffman has posted some quick and easy instructions for running Sugar ("essentially a virtual XO") on Ubuntu Gutsy Gibbon. If you don't have a giant screen, check out these instructions for tips on using a lower resolution (you'll need to do something like vi `which sugar-emulator` to edit the startup script). This might hold you over while you wait for your GOGO order to arrive.

Running Sugar on Ubuntu Gutsy - Link

November 26, 2007

HOWTO - Install Ubuntu on the Asus Eee PC

Paul McGuinness sent us a howto for installing Ubuntu on the Asus Eee PC. For the most part, the install is fairly straightforward, but there are a few performance tweaks that are different from a typical desktop system. The big one is that you want to disable the access time feature (noatime parameter in fstab) of the filesystem to minimize disk writes.

There are also a number of non-standard drivers that you'll need to grab to get things like the wireless card, webcam and sleep features working. The eeeuser.com wiki has an page that describes in detail how to take care of all these issues. Credit to them for the above photo as well.

I peeked at one of these in a store the other day and the hardware seems really sweet. The included OS interface leaves a bit to be desired for someone who's comfortable and familiar with Linux, so it's good to see most everything (save for hibernation and a few function keys) is working on a stock Linux distro. I'll be asking Santa for one of these this year.

Installing Ubuntu 7.10 Gutsey Gibbon on an Asus Eee PC - Link
EeeUser.com Wiki: Ubuntu 7.10 on Eee PC - Link

November 12, 2007

OLPC telepresence robot

Instructables hosted an iRobot Create competition a little while ago, and one of the third place winners was Damon Kohler's OLPC Telepresence bot. It mashes two of my favorite consumer product designs into a cute mutant bot that's controllable via a web interface.

Rather than a huge electronics/robotics exercise, this project is fairly accessible to anyone with a little programming know-how. Aside from some simple wiring, the majority of the work is in the software. Damon has created a high level Python interface, called PyRobot, for controlling the Create and interfacing with the OLPC's webcam. With an afternoon of effort, you could be hacking your own little telepresence bot that you can view and control over the internet.

OLPC Telepresence Instructable - Link
PyRobot - Link
OLPC Telepresence Project Blog - Link

November 8, 2007

VIA's gOS developer kit: cheap low-power Linux

Recently, I've heard a lot of people talking about the Everex TC2502, a $200 Linux PC that's now selling at Walmart, and it's probably not because "TC2502" is such an awesome name. By most standards, it's a pretty slow system. What's different is that it's packaged and sold with Ubuntu Linux and Google's various desktop and web-based office applications. This is a pretty cool thing, and hopefully a lot of non-technical, every-day computer users are going buy these things and have a pleasant Linux+Firefox+web-app experience, sans viruses, spyware, and other Windows genuine advantages.

The other cool thing is that the little 1.5 GHz VIA Micro-ATX system that powers the TC2502 is being sold as a "developer kit" for $60. A normal system, including a hard drive, probably pulls about 30 Watts in normal use. This might make a nice, low-power hacker's desktop. Those of you who still run a fast window manager like Window Maker and spend most of your time shuffling though 8 terminal windows all running VI know what I'm talking about. For the rest of you, a low-power backup server might be a nice eco-friendly change from the noisy-fan, giganto-tower, space heater you have running in the corner of your office.

Low-cost board runs Linux, Google Apps - Link
$60 gOS Develop Kit - Link

November 4, 2007

HOWTO - Make your Linux desktop look like Leopard

The latest release of the Mac4Lin project brings the Leopard look and feel to Linux. There are a number of steps you need to go through to get your GNOME desktop and GTK-based apps all looking consistent, but when you're done, the makeover is quite convincing. The only giveaway is that menus remain attached to each window, instead of displaying at the top of the screen when a window is active.

Infra Red Dude wrote a thorough guide for installing Mac4Lin and tweaking all of your applications. He covers everything from upgrading your fonts and system sounds to changing the GRUB splash screen so that your Linux box boots with the Apple logo.

Mac4Lin Installation Guide - Link
Mac4Lin project - Link

October 18, 2007

Remote snapshot backups with rsync and Samba

Thanassis Tsiodras writes:

What would you do if you had to automatically backup a remote Linux box (e.g. your web server), and all you had locally was Windows machines? How about this:
automatically expanding local storage space
transmissions of differences only
automatic scheduling
local storage of differences only
secure and compressed transfer of remote data and
instant filesystem navigation inside daily snapshot images

I covered all these requirements using open source tools, and I now locally backup our 3GB remote server in less than 2min!

We've all used Samba and rsync before, but Thanassis has really put all the pieces together into a complete backup system that's superior to a lot of commercial products I've seen.

The really impressive bit is how he's easily doing snapshot images using filesystem hardlinks. You can save several days worth of snapshots at very little cost because additional space is only taken up by files that have changed. Using hardlinks, identical files from different snapshots all point to the same inode.

root# mount /dev/loop0 /mnt/backup root# cd /mnt/backup root# rm -rf OneBeforeLast root# cp -al LastBackup OneBeforeLast root# cd LastBackup root# rsync -avz --delete root@hosting.machine.in.US:/ ./
The "cp -al" creates a zero-cost copy of the data (using hardlinks, the only price paid is the one of the directory entries, and ReiserFS is well known for its ability to store these extremely efficiently). Then, rsync is executed with the --delete option: meaning that it must remove from our local mirror all the files that were removed on the server - and thus creating an accurate image of the current state.

And here's the icing on the cake: The data inside these files are not lost! They are still accessible from the OneBeforeLast/ directory, since hard links (the old directory entries) are pointing to them!

In plain terms, simple navigation inside OneBeforeLast can be used to examine the exact contents of the server as they were BEFORE the last mirroring.

Just imagine the data recovery headaches you could solve by adapting that to a cron job that shuffles a months worth of nightly backups.

Optimal remote Linux backups with rsync over Samba - Link

October 8, 2007

Running Puppy Linux inside OS X

Sometimes it's nice to have a secure and familiar OS that you can use from any machine. Puppy Linux is just that: a really lightweight, CD-based Linux distribution, designed for maximum portability. If you're using a PC, you simply boot and run Puppy Linux from a CD, storing your settings and changes to a file on your hard disk or flash drive. What's awesome is that it's so compact, you can fit an emulator, the CD ISO, and the save state files all on a flash disk or SD Card, making it one tiny little OS package that you can carry in your pocket.

Using Q, the OS X port of the QEMU virtual machine, you can create a small footprint, virtual Puppy Linux box that will run under OS X and fit on a flash drive. In addition to its portability, this is one of the easiest ways to get Linux running on your mac.

You could have a little portable Linux box running on your Mac in a half hour. So let's get started.

Read full story

October 3, 2007

HOWTO - read RSS with a POP email client using FreePOPs

FreePOPs is an open source, plugin-based POP proxy that you can run on your local machine. It was originally designed to allow you to use a normal POP email client to read your mail on a multitude of webmail systems. You point your mail client at the FreePOPs server, and it connects and screen-scrapes your webmail account so that you can read your email in the comfort of your favorite mail reader.

The great thing about FreePOPs is its filter plugin architecture. There are a number of different plugins to support the specific requirements of most of the popular web-based email systems. There's even an RSS plugin that will pull an RSS feed and make it look like a normal POP mailbox. Thankfully, you don't need to configure anything on the server. Instead, you connect to the FreePOPs server using a particular username and password format to activate the appropriate plugin.

Here's how to set up an RSS-to-POP mailbox using FreePOPs and the standard OS X Mail.app email client.

Read full story

September 27, 2007

Packet Garden

Packet Garden is a network visualization tool that maps your network traffic into a 3D representation, sprouting little plants on a globe whenever a connection is made.

To do this, Packet Garden takes note of all the servers you visit, their geographical location and the kinds of data you access. Uploads make hills and downloads valleys, their location determined by numbers taken from internet address itself. The size of each hill or valley is based on how much data is sent or received. Plants are also grown for each protocol detected by the software; if you visit a website, an 'HTTP plant' is grown. If you share some files via eMule, a 'Peer to Peer plant' is grown, and so on.

Packet Garden is GNU licenced and written in Python, so you can give it a try on supported Linux, Windows, and Mac machines. It doesn't run on Intel macs, unfortunately. As far as I can tell, Soya3D (the 3D library it uses) is the culprit and has not been compiled under this architecture. Anyone want to take a stab at porting this? I'm not familiar with the package, but it might be as simple as installing all Soya's required libraries and running a python make script.

Packet Garden. Grow a world from network traffic - Link
Soya3D - Link

September 20, 2007

Run GTA2 on Linux

Rockstar released a few of their classic games as a free download, including the original Grand Theft Auto series. The games are distributed as Windows executables, but you can still enjoy a little top-view criminal activity in Linux by running them under WINE.

Revive your Inner Carjacker: GTA2 on Linux - Link
Rockstar Classics (download the games here) - Link

August 4, 2007

Cryptographic key recovery from Linux memory dumps

I stumbled across this paper from the 2007 Chaos Communication Camp which describes a method for extracting the cryptographic keys used by either dm-crypt or cryptoloop.

Technically, the cryptographic keys need to reside in memory while your encrypted disk is in use, so, obviously, if an attacker has access to your physical RAM, they will be able to obtain these keys and decrypt the volume at any future point in time. There were a couple of less-than-obvious takeaways, however.

The first is that there are a multitude of avenues for accessing a machine's memory. Anyone able to obtain root access could access /dev/mem remotely, but many systems (especially laptops) will actually write the memory's contents to disk during extended hibernation. Virtualization software, such as VMWare, will do exactly the same when the virtual machine is suspended. Finally (and this was news to me), the Firewire standard provides devices DMA access. You could imagine a device specifically designed for the purpose of connecting to a running machine. It would copy the machine's ram to a small hard disk, a "finished" LED would light up, and the attacker would pocket it and exit the building. The operating system wouldn't even know that anything had happened.

The second big takeaway is that it's relatively simple to search for these keys in a full memory dump. The method is slightly different for dm-crypt than it is for cryptoloop, but it basically involves a pattern search for certain characteristics in the C data scructure that holds the key. There are a couple of scripts included in the appendix for those of you who'd like to try this out.

If you use disk encryption on a laptop to protect your data from theft while you are traveling, take note. Disable hibernation mode to prevent RAM from being written to disk and do not leave your machine running while unattended, even if logged out.

Cryptographic key recovery from Linux memory dumps - Link (pdf)

July 5, 2007

Text-mode YouTube

You'll probably never have the desire or need to download and watch a YouTube video on a text-only console, but doesn't it make you feel better knowing that it can be done?

The trick is to use the AAlib ascii image library as an output device for mplayer, using the -vo parameter:

mplayer -vo aa video.flv

Mplayer will decode the flv frames, process them with AAlib and print luscious video to your console window. At 80x25, it's almost 2 whole kilopixels of resolution! [via]

Watch Videos in ASCII Art - Link
Linux Multimedia Hacks - Link
AAlib ASCII Graphics Library- Link