Go back to fronty page View most popular entries View latest additions Submit tutorials to UnixTutorials.info
UnixTutorials logo

Search results for Creating secure wireless access points with OpenBSD and OpenVPN

RedHat Choosing an I/O Scheduler for Red Hat Enterprise Linux 4
Post date: July 18, 2005, 18:07 Category: Benchmarks Views: 176
Tutorial quote: The Linux kernel, the core of the operating system, is responsible for controlling disk access by using kernel I/O scheduling. Red Hat Enterprise Linux 3 with a 2.4 kernel base uses a single, robust, general purpose I/O elevator. The 2.4 I/O scheduler has a reasonable number of tuning options by controlling the amount of time a request remains in an I/O queue before being serviced using the elvtune command. While Red Hat Enterprise Linux 3 offers most workloads excellent performance, it does not always provide the best I/O characteristics for the wide range of applications in use by Linux users these days. The I/O schedulers provided in Red Hat Enterprise Linux 4, embedded in the 2.6 kernel, have advanced the I/O capabilities of Linux significantly. With Red Hat Enterprise Linux 4, applications can now optimize the kernel I/O at boot time, by selecting one of four different I/O schedulers.
Linux Creating Really Teensy ELF Executables for Linux
Post date: April 12, 2005, 14:04 Category: Miscellaneous Views: 34
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.
Unix+clones Making Web Browsing Easy For The Tiny Screen
Post date: August 9, 2005, 15:08 Category: Network Views: 73
Tutorial quote: An avalanche of content will soon appear in the palm of your hand.

Tiny screens are showing up everywhere in PDAs and cell phones. Many are equipped with some form of network device and a browser, so it's not hard to see what's coming down the pike.

Late model PDAs, like my HP iPAQ 3715 no longer suffer from insufficient computing power, lack of memory or having to rely on pricey external 802.11b cards. The little machine is quick to boot up and can handle many daily business functions.

Even though it runs a version of Internet Explorer, jumping onto an access point and browsing web pages is fast and useful.

In this edition, I'll share my observations on things you might consider when converting LAMP (Linux, Apache, MySQL, PHP) applications or web pages, for use on the tiny screen. I'll approach the issues from an iPAQ user perspective and focus on convenience and making the user's life easy.
Linux Removing A User
Post date: April 7, 2006, 20:04 Category: System Views: 10
Tutorial quote: Employee turnover in most organizations runs high. So unless you run a small shop with a stable user base, you need to learn how to clean up after an employee leaves. Too many so-called system administrators do not understand the stakes involved when they manage users. Disgruntled former employees can often cause significant trouble for a company by gaining access to the network.

To remove a user, you need to learn to manage all of his or her files, mailboxes, mail aliases, print jobs, recurring –(automatic) personal processes such as the backing up of data or remote syncing of directories, and other references to the user. It is a good idea at first to disable the account in /etc/passwd, after which you can search for the user's files and other references. Once all traces of the user have been cleaned up, you can remove the user completely—but if you remove the entry from /etc/passwd while these other references exist, you have a harder time referring to them .

When you remove a user, it's a good idea to follow a pre-determined course of action so you don't forget any important steps; it may even be a good idea to make a checklist so that you have a routine. Following, you will find several items requiring attention.
FreeBSD Lightweight Web Serving with thttpd
Post date: November 30, 2005, 19:11 Category: Software Views: 79
Tutorial quote: The Apache HTTP Server is the most popular web server due to its functionality, stability, and maturity. However, this does not make it suitable for all uses: slow machines and embedded systems may have serious problems running it because of its size. Here is where lightweight HTTP servers come into play, as their low-memory footprints deliver decent results without having to swap data back to disk.

Similarly, these small HTTP servers are suitable to serve static content efficiently so as to allow Apache, mod_perl, mod_python, or even servlet containers to handle dynamic requests without tying up memory-hungry children to serve small images. In other words, these applications can serve as a complement to your existing full-featured web server, not as a replacement.

One of these servers is thttpd, a simple, small, portable, fast, and secure HTTP server. Among its features are support for the HTTP/1.1 standard, CGIs, virtual hosts, and IPv6. This article shows how to install and configure this software under NetBSD. I chose NetBSD not only because it is my preferred OS, but also because it has the ability to run on the most disparate old hardware, where thttpd shows its strengths. I had a Macintosh Performa 630 (a 68LC040 chip at 33MHz) running NetBSD/mac68k 2.0 with thttpd on top of it, serving pages to my home network nicely.