nixCraft Linux Sys Admin Blog

Google Announces Linux Kernel Based Chrome OS

Vivek Gite — 2009-07-08T17:49:05+01:00

Google has announced Google Chrome OS, which should be available mid-2010. This is a direct challenge to MS Windows operating systems. This is excellent news and it is going to tied tightly to its Chrome Web browser. Google Chrome running within a new windowing system on top of a Linux kernel. Speed, simplicity and security are the key aspects of Google Chrome OS - said Sundar Pichai, VP Product Management, in a blog post.

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?

Software Vs Hardware RAID

Vivek Gite — 2009-07-07T21:01:56+01:00

A redundant array of inexpensive disks (RAID) allows high levels of storage reliability. RAID is not a backup solution. It is used to improve disk I/O (performance) and reliability of your server or workstation. A RAID can be deployed using both software and hardware. But the real question is whether you should use a hardware RAID solution or a software RAID solution.

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

Vivek Gite — 2009-07-01T10:25:00+01:00

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.

20 Linux System Monitoring Tools Every SysAdmin Should Know

Vivek Gite — 2009-06-27T07:26:39+01:00

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.

My 10 UNIX Command Line Mistakes

Vivek Gite — 2009-06-21T07:26:29+01:00

Anyone who has never made a mistake has never tried anything new. -- Albert Einstein.

Here are a few mistakes that I made while working at UNIX prompt. Some mistakes caused me a good amount of downtime. Most of these mistakes are from my early days as a UNIX admin.

Lighttpd Traffic Shaping: Throttle Connections Per Single IP (Rate Limit)

Vivek Gite — 2009-06-21T05:02:13+01:00

If you do not control or throttle end users, your server may run out of resources. Spammers, abuser and badly written bots can eat up all your bandwidth. A webserver must keep an eye on connections and limit connections per second. This is serving 101. The default is no limit. Lighttpd can limit the throughput for each single connection (per IP) or for all connections. You also need to a use firewall to limit connections per second. In this article I will cover firewall and lighttpd web server settings to throttle end users. The firewall settings can be applied to other web servers such as Apache / Nginx and IIS server behind PF / netfilter based firewall.

Slowloris DoS Tool: It Can Bring Down Apache 1.x/2.x

Vivek Gite — 2009-06-19T19:50:39+01:00

Apache Security Update - a flaw In Apache can be used to carry out DoS. Slowloris is a new Apache DoS tool which can use slow Internet links to bring down Apache servers, rather than flooding networks. Most D/DoS tool requires faster net connections but this tool works with minimal bandwidth. This tool can lead to a DoS attack on Apache 1.x, 2.x, dhttpd, GoAhead WebServer, and Squid, while MS IIS6.0, IIS7.0, and lighttpd are confirmed not vulnerable to this attack.

How A Microsoft Veteran Learned To Love Linux And Why It Matters

Vivek Gite — 2009-06-19T03:50:37+01:00

Great article.

"After The Software Wars", is a new book in which former Microsoft employee Keith Curtis explores the worlds of proprietary and free software. Quoting from the article:

While I came to not be all that thrilled with Fedora itself, I was floored merely by the installation process. It contained a graphical installer that ran all the way to completion, it resized my NTFS partition -- which I considered a minor miracle, setup dual boot, and actually did boot, and let me surf the Web. I didn't have a clue what to do next, but the mere fact that this all worked told me more about the potential of Linux than anything I had read so far. You cannot, by accident, build an airplane that actually flies.

=> How a Microsoft veteran learned to love Linux, and why it matters

Visual Representations Of Linux File Systems

Vivek Gite — 2009-06-17T00:49:38+01:00

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

Download Fedora 11 CD / DVD ISO

Vivek Gite — 2009-06-10T12:06:24+01:00

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.

Linux Disable Wireless Networking ( Wi-Fi )

Vivek Gite — 2009-07-10T14:00:31+01:00

We have over 20+ Dell Precision M6400 laptops pre installed with Red Hat Enterprise Linux version 5.x. I was asked to disable Wi-Fi on all laptops as it poses a serious security risk to our sensitive (classified) systems and networks. How do I disable wireless networking (802.11) under Linux?

Answer to "Linux Disable Wireless Networking ( Wi-Fi )"

RHEL / CentOS: yum Lists / Installs Only Security Updates

Vivek Gite — 2009-07-10T00:39:04+01:00

How do I only list or install only security updates under RHEL 5.x or CentOS Linux server? How do I find out security updates descriptions such as CVE, bugs, issued date and type for each patch?

Answer to "RHEL / CentOS: yum Lists / Installs Only Security Updates"

FreeBSD Install DJBDNS Server

Vivek Gite — 2009-07-08T13:57:14+01:00

djbdns's tinydns server is one of the second most popular DNS server with security in mind. How do I install DJBDNS server under FreeBSD operating systems?

Answer to "FreeBSD Install DJBDNS Server"

UNIX / Linux: Send E-mail When sudo Runs

Vivek Gite — 2009-07-01T12:17:05+01:00

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"

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

Vivek Gite — 2009-06-30T18:34:27+01:00

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"

Configure Linux As Bastion Host

Vivek Gite — 2009-06-27T02:13:58+01:00

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

Vivek Gite — 2009-06-26T23:34:03+01:00

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"

Linux Disable Shell / FTP Access For a User Account

Vivek Gite — 2009-06-24T15:01:05+01:00

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"

Ubuntu Linux Save / Restore Iptables Rules

Vivek Gite — 2009-06-24T14:49:04+01:00

I want to make changes to an iptables configuration. How to do I Save and Restore an iptables Configuration in Ubuntu Linux server?

Answer to "Ubuntu Linux Save / Restore Iptables Rules"

PHP Add Captcha Protection To Web Forms

Vivek Gite — 2009-06-24T14:37:59+01:00

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"