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Debian

Setting Up A PXE Install Server For Multiple Linux Distributions On Debian Lenny

Post date: May 26, 2009, 10:05 Category: Miscellaneous Views: 7651 Comments
Tutorial quote: This tutorial shows how to set up a PXE (short for preboot execution environment) install server on Debian Lenny. A PXE install server allows your client computers to boot and install a Linux distribution over the network, without the need of burning Linux iso images onto a CD/DVD, boot floppy images, etc. This is handy if your client computers don't have CD or floppy drives, or if you want to set up multiple computers at the same time (e.g. in a large enterprise), or simply because you want to save the money for the CDs/DVDs. In this article I show how to configure a PXE server that allows you to boot multiple distributions (i386 and x86_64): Debian Lenny, Ubuntu 9.04, Fedora 10, CentOS 5.3, OpenSuSE 11.1, and Mandriva 2009.1.
Linux

Creating a safe directory with PAM and Encfs

Post date: June 7, 2006, 20:06 Category: Security Views: 3766 Comments
Tutorial quote: Now, in my network (and others) the credentials provided at login could (and should) be used by those programs. How can you retrieve these credentials, providing enough security?
With a the PAM modules pam_script it's possible to store the password in a file, which will be used by fusemb and mount.cifs to read the password from.

To achieve security, one could make the user logging in owner and deny read/write for anybody else. Remove this file when the user ends his/her session.
This is enough, for runtime. But I was wondering, but what if the system crashes, and the file with the credentials remains on the harddrive? Anybody who is able to mount this harddrive with for example a lifecd, can read this file!

That's why I was looking for a way to encrypt this file.

With encfs this is very possible! At run time it gives an interface to encrypted files and directories, which does only exist at runtime! When the system is not running, there are only encrypted files, useless when you do not know the key to it. And this key is exactly the (encrypted) password! That's why I've chosen for a combination of PAM and Encfs.
Ubuntu

Setting Up A PXE Install Server For Multiple Linux Distributions With Ubuntu Edgy Eft

Post date: December 20, 2006, 01:12 Category: Installing Views: 4517 Comments
Tutorial quote: This tutorial shows how to set up a PXE (short for preboot execution environment) install server with Ubuntu 6.10 (Edgy Eft). A PXE install server allows your client computers to boot and install a Linux distribution over the network, without the need of burning Linux iso images onto a CD/DVD, boot floppy images, etc. This is handy if your client computers don't have CD or floppy drives, or if you want to set up multiple computers at the same time (e.g. in a large enterprise), or simply because you want to save the money for the CDs/DVDs. In this article I show how to configure a PXE server that allows you to boot multiple distributions: Ubuntu Edgy/Dapper, Debian Etch/Sarge, Fedora Core 6, CentOS 4.4, OpenSuSE 10.2, and Mandriva 2007.
Unix+clones

High Performance MySQL

Post date: December 1, 2006, 04:12 Category: Optimizing Views: 6330 Comments
Tutorial quote: The operating system your MySQL server runs on and the server's configuration can be just as important to your server's performance as the indexes, schema, or queries themselves. In this chapter, we will help you understand how to tune your server to improve performance, as opposed to tuning schema or queries. We'll be looking at changes to your hardware, operating system, and MySQL configuration to see what effects they have on overall performance.

We assume that you've already made efforts to boost the performance of your queries. If you haven't done that already, stop now and read Chapter 4 and Chapter 5 to get a handle on optimizing your queries and your application code. Only then should you worry about server settings. Hardware is often not the solution to MySQL performance problems. Poorly optimized queries can slow you down far more than not having the latest CPU or SCSI disk. To put this in perspective, one of the MySQL AB trainers even says that changing hardware might, in the best cases, give you a 10-fold performance increase. But tuning queries (and schemas) can often give you 1000-fold performance increase. Seriously.

Some topics covered in this chapter are platform-specific. The authors' knowledge of the various platforms on which MySQL runs is limited. In many cases, you'll need to consult your local documentation for various operating system tools and specifics.

We start with an overview of the factors that limit performance and then look more in depth at RAID, hardware, and operating system issues. The chapter finishes with a discussion of techniques you can use to locate, identify, and fix bottlenecks.
Linux

Creating Really Teensy ELF Executables for Linux

Post date: April 12, 2005, 18:04 Category: Miscellaneous Views: 3107 Comments
Tutorial quote: If you're a programmer who's become fed up with software bloat, then may you find herein the perfect antidote.

This document explores methods for squeezing excess bytes out of simple programs. (Of course, the more practical purpose of this document is to describe a few of the inner workings of the ELF file format and the Linux operating system. But hopefully you can also learn something about how to make really teensy ELF executables in the process.)

Please note that the information and examples given here are, for the most part, specific to ELF executables on a Linux platform running under an Intel-386 architecture. I imagine that a good bit of the information is applicable to other ELF-based Unices, but my experiences with such are too limited for me to say with certainty.

The assembly code that appears in this document is written for use with Nasm. (Besides being more appropriate for our needs, Nasm's syntax beats the hell out of AT&T syntax for anyone who learned x86 assembly language before learning to use Gas.) Nasm is freely available and extremely portable; see http://nasm.sourceforge.net/.

Please also note that if you aren't a little bit familiar with assembly code, you may find parts of this document sort of hard to follow.
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