How to enable Debug repository in CentOS Linux. Updated: March 6, 2010 This article is a part of my Linux Kernel Crash Book. It is available for free download in PDF format! Normally, I try to avoid providing distro-centric solutions and go for across-the-board, agnostic answers that should weather the trial of time and space. This is not always possible, as evident in the title of this article. Why CentOS and why Debug repositories? Well, if you recall, we had two very long tutorials on Kernel crash dump collection, one for the older LKCD utility and one for Kdump.
In these two sessions, we learned how to setup the tools, crash the system and dump memory cores to a hard disk. Introduction While the crash tutorial is still a few days off, getting your system prepared is a good idea. You will need to tick the Enabled checkbox under Properties. On CentOS, it's even worse, with Debug repositories missing entirely.
Why CentOS? Enable repositories The default repository list does not have the Debug repo either included or enabled. Here we go: Linux cool hacks - Part II. Updated: March 22, 2010 Hello there, dear readers. Time for the second article of highly useful, cool and fun utilities, commands, and tricks that should help you gain better productivity and understand your system better. In the first part, we learned about a whole bunch of great things, including top in batch mode, how to read process account logs, how to measure system activity with a range of programs, and how to write a simple UDP server-client. Now, let's see a few more tricks that will help you master a higher, cooler level of Linux knowledge and allow you to impress you significant others, including your boss. 1.
Sparse files What they be, you're askin'. If you're a fan of virtualization, you have come across sparse files - virtual machines disks can be sparse files. Well, sparse files are definitely useful in virtualization, but they have other uses. Create sparse files Creating sparse files is very simple. Dd if=/dev/zero of=file bs=1 count=0 seek=1M 2. Atop -w /tmp/atop.raw 30 10. Do I need an anti-virus in Linux? Updated: March 26, 2010 Big question. Windows users and recent converts often ask them. A classic mistake, making a rather linear, one-for-one comparison between Windows and Linux. But no matter. I'm not here to berate. I'm here to educate. And I'd like to answer this very crucial, if very simple question. First, a secret Yes, let me tell you a little secret.
The truth could be not be farther from the truth [sic]. A much better, fool-proof security is achieved by the right kind of strategy and a reasonable, layered approach to identifying threat vectors and mitigating them. Since this article is mainly intended for Windows users mulling a move to Linux and new, less experienced users wondering how secure their Linux box is, first here's a selection of articles and tutorials that should help you focus your efforts correctly. Safe Web practices - How to enjoy Internet and be safe, without unplugging the cable. SuRun - How to run a limited account on Windows, easily. Reason 1: User account. New cool list of Linux must-have programs. Update: A new, up-to-date collection is available. Please take a look! It's been approximately two years since I've written the first article, A (cool) list of Linux tools.
The article proved quite popular with my audience, as it allowed Linux users, new converts in particular, a quick taste of some of the more useful programs available for Linux platforms, across a range of categories. Since, a lot has changed. Changes from the last time Like the last time, the programs will be sorted by categories. Games I will not be listing games here. Users' recommendations Likewise, there's a users' recommendation sub-section, so you can send me your suggestions and ideas. Table of Contents: Backup software File backup software Unison Unison is a simple, lightweight backup program. TimeVault TimeVault is a snapshot software, which, when activated will create copies of all files and folders that change, retained a detailed archive of all revisions.
Imaging software CloneZilla Mondo & Mindi PartImage Remastersys. A place to learn about computer software, security and games, popular physics, life, 3d art, models, and more. Web. How to configure RAID in Linux. Updated: June 26, 2009 Not that long ago, we've had a long, extensive tutorial on GParted, a powerful and friendly partitioning software that allows you to configure your drives and partitions for installations of multiple operating systems. The tutorial helped us learn the Linux vernacular and we mastered the basic configurations, like creating, resizing, moving, and deleting of partitions, and even some more advanced stuff. In all cases, we worked with individual partitions. We did not dabble in RAID. In the tutorial, I only briefly mentioned RAID and LVM.
In both cases, GParted could display some information on these setups, but it was incapable of creating them. I promised separate tutorials on both subjects - and here we are. In this tutorial, we will learn what RAID is, both the acronym and the principle. Quite a lot - and as always, step-by-step, with lots of images and in great detail, no steps skipped or assumed, with real life examples throughout. Let us begin. Now, let's start. How to print from Linux machines to Windows printers over Wireless. Updated: June 10, 2009 The title definitely sounds delicious. And you must be thinking this is going to be difficult. Not at all. As simple, if not simpler, than doing it in Windows. Task at hand We have a multi-host network (LAN), with a Lexmark printer connected to a Windows XP machine.
You may think this is going to be a suicide ... ? In fact, this is going to be a task taking just 3 minutes, no command line at all. Demonstration done in Ubuntu 8.10. Configuring printer - 10 easy steps Step 1: Add new printer Click on System > Administration > Printing. Step 2: Choose connection We need to tell our machine where to look for the printer. Step 3: Browse for printer In the right pane, click on Browse. Step 4: Verify connection Your printer is now selected. But let's make sure we have sufficient permissions and that can print to it. Step 5: Choose vendor In this particular case, I know that there is no driver for this particular printer available in Linux. Step 6: Choose model Like we said above: Mondo & Mindi - Disaster recovery solution. Updated: June 4, 2009 Being able to suffer a disaster and recover quickly thereafter is the manifest of good planning.
Even if we're only talking about desktop use, to say nothing of businesses, the need to preserve years of work, art, passion, family legacy, intellectual property, and any other dear, irreplaceable data is paramount. The difference between a minor fuss of wasting a few minutes recovering after a crisis, whether it is hardware failure, theft or plain mistakes, and days or weeks of grueling pain trying to salvage years of precious digital data lies in careful preparation. We do this by identifying our needs and risks and adjusting accordingly. Most people keep data on CD/DVDs, some use external hard disks and tapes, while some opt for online backups. Either way, we make sure there's a backup ready once the storm is over. Therefore, choosing the right backup solution is probably the most important phase of all. Mondo fits the bill. Best of all, you can also use it at home. How to open .chm files on Linux.
Updated: June 1, 2009 CHM stands for Microsoft Compiled HTML files. This is a proprietary format that is used on Microsoft Windows to bundle multiple HTML (help) files into a single e-book style document, so that users can comfortably browse the content rather than getting lost in tens or even hundreds of separate documents. The effort is benevolent, but somewhat redundant considering the same can be achieved using PDF, which makes more sense cross-platform.
However, Microsoft have never been known for great compliance with cross-platform standards, which leaves Linux users, who might need to take a look at a collection of their CHM files, in a bit of a spot. Truth to be told, the chances of having to use CHM files on Linux are rather slim, but it does not hurt to have that ability, even if it never gets used. This is particularly true for people dual-booting Windows and Linux. Luckily, the solution is very simple: xCHM. xCHM Right-click and choose to open with xCHM: And another screenshot: How to open .mht files in Firefox on Linux. Updated: May 30, 2009 Contrary to popular belief, .mht files are not a Microsoft conspiracy. They are a legitimate standard, allowing you to save webpages as a single file rather than as an .html file and a whole directory of images, scripts, and other accompanying files. There's one problem - it seems that Firefox can't handle these files well.
If you try to open them on Linux, even if Firefox is your default web browser, the files will be opened using a text editor or an alternative browser (like Opera), capable of correctly handling the .mht files. Test case - an .mht file To create the problem, I opened my own site in Opera and chose to save the file. After I saved the file, it shows in the file manager as a text file. Double-clicking on the file will open it in Opera, which is not the default browser. Firefox will start, but it will not display the file. So you will try to "fool" Firefox. So, this is not the right way of doing it.
Solution - Firefox Addons! And here we go: Conclusion. Never lose a file with TimeVault. Updated: May 29, 2009 TimeVault is a powerful backup system that will create automated snapshot for every file change on your system. This means you will be able to retain all and any changes of your critical system files, configurations and personal documents, without worrying about manually copying them. The backup and the revision change are all done in the background, as often as 1 minute apart, giving you total control over your system. Don't like the changes you made to a file in the last 7 minutes 43 seconds? Just revert to a snapshot eight minutes earlier. It's that simple. Using TimeVault TimeVault is meant for Gnome desktop and is currently not included in the repositories.
The first time you run TimeVault, you won't see anything significant, except the icon in the system area. Clicking on it will open the list of all pending snapshots, which thereof won't be any for now. Under Preferences, we can configure TimeVault. TimeVault in action Give it a minute or two. Conclusion Cheers. How to easily manage your Linux firewall with gufw. Updated: May 20, 2009 Linux is well known for its powerful firewall called iptables. However, this firewall must be managed from the command line, using long, boring and even somewhat difficult commands. Thus, it is virtually inaccessible to most users. In Ubuntu, the situation is even worse, because the firewall is turned off by default and there is no easy way to start it up. Getting the firewall controlled like any other services requires writing a few scripts, hardly an everyday task for an everyday man.
To make iptables more manageable on Ubuntu, Uncomplicated Firewall (ufw) was born. This tutorial will show you how you can easily manage your Linux firewall using gufw, start/stop the service, create rules, monitor logs, etc - all without ever once touching the command line. Note: A small clarification: ufw and gufw are utilities specifically intended for Ubuntu, but you can run them on other distributions with some modifications. Install gufw Start gufw Add rules Preconfigured rules. Wicd - A friendly network manager for Linux. Updated: May 18, 2009 Network managers are utilities that allow users to control the network in their operating systems. This includes configuring various network devices, setting up IP addresses, dialing connections to ISPs, and other settings.
Every operating system has a network manager. Some are GUI, some are command line, some are friendly, others are not. Whatever their look and feel, they do one thing - allows us to change important network settings without directly accessing different configuration files that define the network. Linux distros have a broad range of managers. In KDE, the default utility is called KNetworkManager. Then, with the release of Ubuntu 8.10 Intrepid Ibex, things got worse. Although I have shown you how you can overcome this issue, you may still want a simpler, friendlier and less buggy network manager instead of the default choice. Enter wicd wicd is a simply, friendly network manager, available for all desktops, be their Gnome, KDE, Xfce, or others.
BackTrack 4 - Hacking galore. Updated: May 15, 2009 We have already had three articles on Linux forensics. This is the fourth. In the first three parts, we had an introduction to basic concepts on and some common tools and two detailed reviews of Helix and Protech, Linux distributions specially designed for penetration testing, security auditing, incidence handling, system investigation and analysis, data recovery, and other useful tasks.
Today, we will review another high-end, security-oriented distribution, BackTrack. Introduction BackTrack is one of the more popular distributions in the white hat circles. Lots of great stuff Like most Linux distros - and definitely all forensics/security-oriented tools, BackTrack works primarily as a live CD, with good hardware detection and low memory footprint, intended to make it usable even on older machines. The boot menu is simple and elegant, with three options available. Anyhow ... Desktop The desktop is simple and functional, running a lightweight KDE3 manager. Tools Errors. Easily manage Linux services with chkconfig and sysv-rc-conf utilities. Updated: May 8, 2009 If you want to manage the services in your Linux distribution without manually hacking the scripts in runlevel directories, you may want to use the chkconfig and sysv-rc-conf utilities. chkconfig is used on RedHat-based distros, sysv-rc-conf is for Debian variants.
Follow me. chkconfig The utility is included by default with RedHat (and sons) and SUSE. This means that system administration is a simple affair on these distributions. Chkconfig --levels <levels><service><switch> What do we have here? --levels <levels> defines the runlevels in which you want the particular service switch to be turned. <service> is the actual service we want enabled/disabled for the listed runlevels. <switch> is on/off, meaning enabled/disabled service for the particular runlevels.
Let's see a practical example: Here, we turned the SSH service (daemon called sshd) off and on in runlevel 2. And we can also list all services using the --list flag: chkconfig --list Let's see what sysv-rc-conf offers: GParted partitioning software - Full tutorial. Updated: April 25, 2009 No matter which operating system you want to have installed on your machine, there's one thing they all have in common: partitions. These are logical pieces of your actual hard disk space, defining the size and the file system format for the operating systems and data that are going to be placed on them. Being able to control the partitions is one of the most basic, most important aspects of mastering your operating system. If you have the knowledge and confidence to manipulate the layout, create it, change it or delete it, you can adapt your hardware to your varying needs, without having to blindly rely on default setups defined by vendors or other people.
After completing this tutorial, you will have learned how to interpret the partitioning dictionary, what the strange symbols, letters and numbers mean. Never again you shall fear using partitioning software or installing operating systems on hard disks already containing data. Table of contents: Or like this: How to use Linux filesystems on Windows. Collecting and analyzing Linux kernel crashes - LKCD. AndLinux - Run Linux natively inside Windows. 6 cool BASH tricks. Protech - A Linux forensics distro you want. Linux forensics - Introduction. How to remotely connect to Linux machines from Windows. Apache Web server - Complete Guide. Installing Wolvix Linux - Full tutorial. Installing Slackware Linux - Full tutorial. Sharing folders between Windows and Linux.
Highly useful Linux commands & configurations. Gnome Shell - One desktop to bind them all. Linux super-duper admin tools: Strace. Profile and visualize Linux boot process with Bootchart. Linux super-duper admin tools: OProfile. Linux super-duper admin tools: screen.