linux admin

Linux Disable Shell / FTP Access For a User Account

Wed, 24 Jun 2009 20:12:51 GMT

My users will only be checking mail, and I want to disable FTP access as well as shell access under CentOS Linux. How do I disable shell (SSH) and FTP access to a new or old user under Linux without deleting user account?

Answer to "Linux Disable Shell / FTP Access For a User Account"

Free White Papers Novell: Open Enterprise Server vs. Windows Server "Upgrade or Migrate" Business Case - Your proposal to migrate to a new server has been approved. But wait, which server environment do you select?

RSS Management

Sat, 04 Jul 2009 08:46:21 GMT

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PHP Add Captcha Protection To Web Forms

Wed, 24 Jun 2009 20:12:51 GMT

I own a small business website. However, bots started to abusing my forms such as contact.php. How do I stop bots bots from abusing my site? How do I tell if PHP form is submitted by a person or a script?

Answer to "PHP Add Captcha Protection To Web Forms"

Download Fedora 11 CD / DVD ISO

Thu, 25 Jun 2009 20:54:20 GMT

Fedora Linux version 11 has been released and available for download ( jump to download link ). Fedora Linux is a community-based Linux distribution. Fedora is sponsored by Red Hat, Inc.

One of Fedora's main objectives is not only to contain free and open source software, but also to be on the leading edge of such technologies. Fedora 11, codenamed "Leonidas", was released on June 9, 2009. The features include ext4, a 20-second startup, and the latest GNOME, KDE and XFCE releases. Firefox 3.5 and Thunderbird 3's latest pre-releases are available as well.

Increase Your VMware Virtual Hard Disk Size ( vmdk file )

Thu, 25 Jun 2009 20:54:20 GMT

I've Windows Vista installed as a guest under Ubuntu Linux using VMWARE Workstation 6.0. This is done for testing purpose and browsing a few site that only works with Internet Explorer. Since I only use it for testing I made 16GB for Vista and 5GB for CentOS and 5GB in size for FreeBSD guest operating systems. However, after some time I realized I'm running out of disk space under both CentOS and Vista. Adding a second hard drive under CentOS solved my problem as LVM was already in use. Unfortunately, I needed to double 32GB space without creating a new D: drive under Windows Vista. Here is a simple procedure to increase your Virtual machine's disk capacity by resizing vmware vmdk file.

FreeBSD Set Network Polling To Boost Performance

Tue, 23 Jun 2009 14:48:09 GMT

I've Intel PRO/1000 Gigabit Ethernet adapter installed in my server. How do I set network card (NIC) polling and disable interrupts under FreeBSD operating systems to boost network performance for 100M and 1000M network links?

Answer to "FreeBSD Set Network Polling To Boost Performance"

Configure Linux As Bastion Host

Fri, 26 Jun 2009 22:21:47 GMT

What is bastion host? How do I configure bastion host under Linux? How do I create a firewall for a bastion host under any Linux distribution?

Answer to "Configure Linux As Bastion Host"

FreeBSD Check The Health of Adaptec RAID Array

Fri, 26 Jun 2009 22:21:47 GMT

I've Adaptec RAID 1 set via 5405 PCI card. I know how to get check the health of Adaptec RAID array under Linux, but how do I find information about my RAID card, RAID status, disk failure and other information via command line?

Answer to "FreeBSD Check The Health of Adaptec RAID Array"

20 Linux System Monitoring Tools Every SysAdmin Should Know

Sat, 27 Jun 2009 22:53:48 GMT

Need to monitor Linux server performance? Try these built-in command and a few add-on tools. Most Linux distributions are equipped with tons of monitoring. These tools provide metrics which can be used to get information about system activities. You can use these tools to find the possible causes of a performance problem. The commands discussed below are some of the most basic commands when it comes to system analysis and debugging server issues such as:

Finding out bottlenecks.
Disk (storage) bottlenecks.
CPU and memory bottlenecks.
Network bottlenecks.

CentOS: Install Packages Via yum Command Using DVD / CD as Repo

Tue, 30 Jun 2009 15:38:06 GMT

How do I install packages via DVD / CD using yum command under CentOS Community Enterprise Linux version 5.x?

Answer to "CentOS: Install Packages Via yum Command Using DVD / CD as Repo"

keychain: Set Up Secure Passwordless SSH Access For Backup Scripts

Mon, 22 Jun 2009 08:04:17 GMT

We establish connections to remote systems without supplying a password, however I do not want to store my password less keys ( passphrase-free keys) on my servers. ssh-agent, takes care of keys with passphase, which allowing me to easily have ssh-agent process per system per login session. How do I dramatically reduces the number of times I've to punch my passphrase from once per new login session to once every time my local server is rebooted? How do I use keychain utility for all my backup scripts for secure passwordless login?

Answer to "keychain: Set Up Secure Passwordless SSH Access For Backup Scripts"

Download Of the Day: Firefox 3.5 For Windows, Linux, Mac OS X

Wed, 01 Jul 2009 23:27:36 GMT

Firefox version 3.5 has been released and available for download. Firefox 3.5 is the fastest web browser. It is twice as fast as Firefox 3. As a result javascript and multimedia enabled web apps loads faster. Firefox is the first browser to support open video and audio formats, allowing practically limitless new ways for sites to display rich content. This is based upon the open formats (HTML 5) which allow displaying media without a plug-in and/or proprietary software.

UNIX / Linux: Send E-mail When sudo Runs

Wed, 01 Jul 2009 23:27:36 GMT

I'm not told to use the root user to perform activities that do not require it. I've configured sudo for myself and for other web developers so that they can restart MySQL or Apache web server. How do I send email when sudo run by one of my user? How do I keep track of user login done via sudo command?

Answer to "UNIX / Linux: Send E-mail When sudo Runs"

Visual Representations Of Linux File Systems

Fri, 03 Jul 2009 02:07:12 GMT

This is an interesting visualization techniques for software analysis. From the article:

Despite being a very important part of any operating system, file systems tend to get little attention. Linux has three editions for Linux Device Drivers, another three for Understanding the Linux Kernel and two for Linux Kernel Development. The first is a detail analysis of one particular Linux Kernel tree and the second is a shorter one done over a large number of file systems from Linux Kernel 2.6.0 to 2.6.29. After that there is a small section that shows some aspects of the BSD family. After conclusions there is an appendix consisting of three things: the first one explains how the file systems for Linux were compiled, the second one shows timelines for the releases of Linux Kernel, FreeBSD, NetBSD and OpenBSD; the last is a detailed map of the external symbols of the kernel modules analyzed in the second section.

A Visual Expedition Inside the Linux File Systems

Tutorial: Four node distributed storage with GlusterFS on Linux

Thu, 25 Jun 2009 20:54:19 GMT

(Posted 25 Jun 2009 by falko)

FreeBSD Disable Bell / Beep ( Hardware beep )

Mon, 22 Jun 2009 08:04:17 GMT

I know how to disable beep sound under Linux, but the settings are not working under FreeBSD laptop. How do I disable beep sound under FreeBSD operating system?

Answer to "FreeBSD Disable Bell / Beep ( Hardware beep )"

Groovy metaprogramming

Thu, 25 Jun 2009 20:54:19 GMT

(Posted 25 Jun 2009 by solrac)

Set up Xen 3.4.1 Dom0 on Ubuntu 9.04

Thu, 25 Jun 2009 20:54:19 GMT

(Posted 25 Jun 2009 by Boris Derzhavets)

Install OpenERP Server on Ubuntu 9.04

Fri, 26 Jun 2009 22:21:46 GMT

(Posted 26 Jun 2009 by falko)

CSS Frameworks for better Web pages

Fri, 26 Jun 2009 22:21:46 GMT

(Posted 26 Jun 2009 by solrac)

Happy 40th Birthday UNIX!

Mon, 22 Jun 2009 08:04:16 GMT

UNIX turns 40 - in 1969 group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna developed UNIX. Today Unix offered in many flavors and developed over time by AT&T as well as various commercial vendors (such as IBM, HP, Sun, Apple etc) and non-profit organizations. CW article concluded that after four decades, the future of the operating system is clouded, but its legacy will endure in form of Linux and Microsoft NT operating system.

Tutorial: Enable Compiz Fusion on Fedora 11 and GNOME

Sat, 27 Jun 2009 22:53:48 GMT

(Posted 27 Jun 2009 by falko)

Tutorial: Build a stealth firewall

Sat, 27 Jun 2009 22:53:48 GMT

(Posted 27 Jun 2009 by Ray)

Robust Clustered Storage with Linux and GFS

Mon, 29 Jun 2009 03:51:33 GMT

(Posted 28 Jun 2009 by Ray)

Newbie guide to programming languages

Mon, 29 Jun 2009 03:51:33 GMT

(Posted 28 Jun 2009 by Ray)

Uninstall / Remove Webmin Software