nixcraft

Information for Linux System Administration

Top Tools For Linux / Unix Forensics Memory Analysis

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You can dump Linux or Unix server memory. This is useful for forensics analysis, and testing your own system. This is often desirable to see:

* What code and what data actually resides in memory.
* You can search for specific pids memory.
* Search memory for string and other data such as passwords.
* Works as add-on tool for gdb and others.
* Search/replace/dump memory from running processes and core files.
* All kinds of deep hacking activities that simply saves your time and solve problems. read more...

mail this link | permapage | score:9655 | -nixcraft, March 26, 2013

OpenBSD Tutorial: Configure Ralink USB Wireless Adapter

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I brought a USB 2.0 wireless adapters based on the Ralink RT2700U, RT2800U and RT3000U chipsets. How do I configure and use it under OpenBSD operating systems?

This usb wireless adapter works out of box under OpenBSD and Linux operating systems. Under OpenBSD you need to use run driver. read more...

permapage | score:9654 | -nixcraft, December 4, 2012

Tutorial: Use Amazon Cloudfront To Speed Up Wordpress Based Site

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A typical WordPress blog contains a mix of static stuff such as images, javascript, style sheets and dynamic content such as posts, pages and comments posted by users. You can speed up your blog by serving static content via content delivery network such as Akamai, Edgecast and so on. The big boys of CDN business also offered the solution to accelerate dynamic content to improve the performance and reliability of the blog. However, solutions offered by big and traditional CDNs are expensive. Amazon cloudfront recently started to serving dynamic content at lowered price. In this blog post, I will explain:

1. How to serve your entire blog using cloudfront.
2. DNS settings.
3. WordPress settings.
4. Documenting limitations of cloudfront.
5. Documenting performance improvements. read more...

mail this link | permapage | score:9632 | -nixcraft, March 7, 2013

Linux Iptables Examples

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Linux comes with a host based firewall called Netfilter. It is a set of hooks inside the Linux kernel that allows kernel modules to register callback functions with the network stack. A registered callback function is then called back for every packet that traverses the respective hook within the network stack.

This Linux based firewall is controlled by the program called iptables to handles filtering for IPv4, and ip6tables handles filtering for IPv6. This tutorial list most common iptables solutions required by a new Linux user to secure his or her Linux operating system from intruders. read more...

mail this link | permapage | score:9624 | -nixcraft, December 14, 2011

Unix: Show Network Interface Card Statistics

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The nicstat command is top like utility for network interface card (NIC). It displays information and statistics about all your network card such as packets, kilobytes per second, average packet sizes and more. It works under Solaris and Linux operating systems.

In this post, I will explain how to install and use the nicstat command to find out stats about your NICs under Debian / Ubuntu / RHEL / CentOS Linux operating systems. read more...

permapage | score:9610 | -nixcraft, March 25, 2013

Squid Proxy HowTo: Listen Pandora to In Europe

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I have Pandora Internet Radio One subscription, and recently I moved to Europe for a few months as part of my work schedule. The service fully available only in the United States. How do I access Pandora one service in Europe? Can I get around it by using a proxy server installed on my own server located in USA at home or ISP data center? read more...

permapage | score:9367 | -nixcraft, November 22, 2012

Boxes: Draw Text Mode ASCII-art

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Boxes command is a text filter and a little known tool that can draw any kind of ASCII art box around its input text or code for fun and profit. You can quickly create email signatures, or create regional comments in any programming language. This command was intended to be used with the vim text editor, but can be tied to any text editor which supports filters, as well as from the command line as a standalone tool. read more...

permapage | score:9353 | -nixcraft, June 12, 2012

Debian / Ubuntu Linux Install OpenSHOT Video Editor

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OpenShot is a free and open source video editor designed to create videos on Linux. This app act as an alternative to iMoive or Windows Movie Maker. I am using Debian Linux 6.x. This version ships with an older version of OpenSHOT software. How can I install the latest version of OpenSHOT under Debian GNU/Linux? read more...

permapage | score:9344 | -nixcraft, December 7, 2012

Top 15 Open Source Unix Terminal Applications

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Linux on the desktop is making great progress. However, the real beauty of Linux and Unix like operating system lies beneath the surface at the command prompt. nixCraft picks his best open source terminal applications of 2012.

Most of the following tools are packaged by all major Linux distributions and can be installed on *BSD or Apple OS X. read more...

permapage | score:9338 | -nixcraft, December 13, 2012

Linux trickle: Bandwidth Throttling for Bash Shell

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I am using a bash shell under Ubuntu Linux operating system. Sometime I need to restrict my own Internet bandwidth for all my shell applications such as ftp, sftp, wget, curl and friends. How do I limit the network speed under bash without setting up a complicated firewall and tc rules. read more...

permapage | score:9322 | -nixcraft, December 8, 2012

Book Review: The Book Of Gimp

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I usually use GIMP (the "GNU Image Manipulation Program") for editing photos, changing colors, resizing photos, applying significant effects and more. It is a free software alternative to Adobe Photoshop. It is also quite popular with graphics artists and webmasters who wants to edit digital images. GIMP is not just a Linux specific program. It works on all leading operating systems, i.e., Mac OS X, MS-Windows and Unix variants. However, like many other powerful open source software, GIMP can be difficult to master. There are many options and plugins. So if, you are looking to learn or master the GIMP program, give The Book of GIMP a try. read more...

mail this link | permapage | score:9310 | -nixcraft, March 8, 2013

Linux Hard Disk Encryption Tutorial

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I carry my Linux powered laptop just about everywhere. How do I protect my private data stored on partition or removable storage media against bare-metal attacks where anyone can get their hands on my laptop or usb pen drive while traveling? read more...

permapage | score:9256 | -nixcraft, October 22, 2012

Linux FTP Server Traffic Shaping

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When traffic is shaped, its rate of transmission is under control. Shaping may be more than lowering the available bandwidth - it is also used to smooth out bursts in traffic for better network behaviour.

This article explains how to control outgoing traffic for the FTP server/service running on Debian/CentOS/Ubuntu Linux server. read more...

permapage | score:9230 | -nixcraft, September 10, 2012

Best Nmap Command Examples For Network Auditing

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Nmap is short for Network Mapper. It is an open source security tool for network exploration, security scanning and auditing. However, nmap command comes with lots of options that can make the utility more robust and difficult to follow for new users.

The purpose of this post is to introduce a user to the nmap command line tool to scan a host and/or network, so to find out the possible vulnerable points in the hosts. You will also learn how to use Nmap for offensive and defensive purposes. read more...

mail this link | permapage | score:9228 | -nixcraft, November 29, 2012

Tutorial: Identify Linux bottlenecks with kSar

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The sar command collect, report, or save UNIX / Linux system activity information. It will save selected counters in the operating system to the /var/log/sa/sadd file. From the collected data, you get lots of information about your server such as:

1. CPU utilization
2. Memory paging and its utilization
3. Network I/O, and transfer statistics
4. Process creation activity
5. All block devices activity
6. Interrupts/sec etc.

sar output can be used for identifying server bottlenecks. However, analyzing information provided by sar can be difficult, so use kSar, which can take sar output and plot a nice easy to understand graph over period of time. read more...

mail this link | permapage | score:9223 | -nixcraft, December 16, 2009

Tutorial: Setup Linux iSCSI SAN

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Linux target framework (tgt) aims to simplify various SCSI target driver (iSCSI, Fibre Channel, SRP, etc) creation and maintenance. The key goals are the clean integration into the scsi-mid layer and implementing a great portion of tgt in user space.

The developer of IET is also helping to develop Linux SCSI target framework (stgt) which looks like it might lead to an iSCSI target implementation with an upstream kernel component. iSCSI Target can be useful:

a] To setup stateless server / client (used in diskless setups).
b] Share disks and tape drives with remote client over LAN, Wan or the Internet.
c] Setup SAN - Storage array.
d] To setup loadbalanced webcluser using cluster aware Linux file system etc.

In this tutorial you will learn how to have a fully functional Linux iSCSI SAN using tgt framework. read more...

mail this link | permapage | score:9171 | -nixcraft, November 14, 2008

Linux Tutorial: Rename a RAID Array

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I am moving a raid array called /dev/md0 from serverA to serverB. On serverB /dev/md0 is already in use. How do I rename a RAID array from /dev/md0 to /dev/md2?

You can move a RAID array (software based RAID array) to another system. However, if /dev/md0 is already is use on serverB, you can rename /dev/md0 as /dev/m2. read more...

permapage | score:9123 | -nixcraft, November 27, 2012

Unix: Shell Script Wrapper Examples

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Shell script wrappers can make the *nix command more transparent to the user. The most common shell scripts are simple wrappers around third party or system binaries. A wrapper is nothing but a shell script that includes a system command or utility.

Linux and Unix like operating system can run both 32bit and 64bit specific versions of applications. You can write a wrapper script that can select and execute correct version on a 32bit or 64bit hardware platform. In cluster environment and High-Performance computing environment you may find 100s of wrapper scripts written in Perl, Shell, and Python to get cluster usage, setting up shared storage, submitting and managing jobs, backups, troubleshooting, invokes commands with specified arguments, sending stdout to stdout and stderr to stderr and much more.

In this post, I will explains how to create a shell wrapper to enhance the basic troubleshooting tool such as ping and host. read more...

mail this link | permapage | score:9105 | -nixcraft, June 24, 2012

Tutorial: MySQL Linux C API

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MySQL database does support C program API just like PHP or Perl API.

The C API code is distributed with MySQL. It is included in the mysqlclient library and allows C programs to access a database.

Many of the clients in the MySQL source distribution are written in C. If you are looking for examples that demonstrate how to use the C API, take a look at these clients. You can find these in the clients directory in the MySQL source distribution.

This tutorial provides a sample MySQL C program and step by step compilation instructions to kick start MySQL programming via C API. read more...

mail this link | permapage | score:9102 | -nixcraft, June 1, 2007

ls* commands more useful than you know

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Everything is a file under Linux and ls* and friends can help you to dig out more information from the system than you originally thought. These Linux tips may come in handy when you need to find out information quickly without going through /proc or sysfs. read more...

permapage | score:9099 | -nixcraft, August 18, 2012

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