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Linux and other Unix-like operating systems use the term “swap” to describe both the act of moving memory pages between RAM and disk, and the region of a disk the pages are stored on. It is common to use a whole partition of a hard disk for swapping. However, with the 2.6 Linux kernel, swap files are just as fast as swap partitions. Now, many admins (both Windows and Linux/UNIX) follow an old rule of thumb that your swap partition should be twice the size of your main system RAM. Let us say I’ve 32GB RAM, should I set swap space to 64 GB? Is 64 GB of swap space really required? How big should your Linux / UNIX swap space be?

The FreeBSD jail mechanism is an implementation of operating system-level virtualization that allows administrators to partition a FreeBSD-based computer system into several independent mini-systems called jails. FreeBSD jails offer security, ease of delegation and os level virtualization. This article explains how to upgrade FreeBSD jails using 'make world'.

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 Linux tgt framework.

Nautilus is the official file manager for the GNOME desktop. It has ability to run add-on scripts written in any scripting language. This tutorial explains how to open a shell prompt or gnome-terminal at the current location while browsing directories and files via nautilus Linux / UNIX Gnome file manager.

IP aliasing is the process of adding more than one IP address to a network interface. This is useful for virtual hosting of Web or ftp servers. This tuorial explains how to assign two more IP address to a single network interface under FreeBSD operating system.

Adobe does not provide a Flash player 10 final for 64 bit Linux systems. This quick howto explains installing the Adobe Flash plugin 10 under 64bit Ubuntu Linux system using a shell script.

Linux ext2/3 filesystem stores superblock at different backup location so it is possible to get back data from corrupted partition. This aricle explains how to recover a bad superblock from a corrupted ext3 partition to get back data.

A port scanner (such as nmap) is a piece of software designed to search a network host for open ports. Cracker can use nmap to scan your network before starting attack. You can always see scan patterns by visiting /var/log/messages. But, I recommend the automated tool called psad - the port scan attack detector under Linux which is a collection of lightweight system daemons that run on Linux machines and analyze iptables log messages to detect port scans and other suspicious traffic.

dnstop is a great tool when maintaining a DNS server. Log file can give out required information but dnstop is just like top command for monitoring dns traffic. It is a small tool to listen on device or to parse the file savefile and collect and print statistics on the local network's DNS traffic. You can see information about all DNS clients, DNS queries and much more with this tool.

The following 10 items are guidelines more than rules, that I have learned over the years doing intensive work on the IT infrastructure. These guidelines are mostly common sense and can be helpful for anybody who administers an IT system, including Linux/Windows Administrator, Network Administrator and DBA.

rsnapshot is easy, reliable and disaster recovery backup solution. It is a remote backup program that uses rsync to take backup snapshots of filesystems. It uses hard links to save space on disk. You can easily build remote / local backup server to keep snapshots in in hourly, daily and monthly format.

You can easily configure IPv6 Tunnel under Debian or Ubuntu Linux to browse IPv6 ready websites and use IPv6 utilities. If your ISP is not ready with IPv6 native transport, you can easily set IPv6 tunnel under Debian or Ubuntu Linux using tspc (tunnel setup protocol client). tspc provides a mean to configure a tunnel obtained from a tunnel server which is compliant to the tunnel setup protocol (TSP).
How To Setup Debian / Ubuntu Linux IPv6 Tunnel Using tspc

This article gives you a jumpstart on performing benchmark on filesystem using iozone a free Filesystem Benchmark utility.

Linux can be configured to log dmesg output to another system via network using syslog. It is done using kernel level networking stuff ia UDP port 514. There is module called netconsole which logs kernel printk messages over udp allowing debugging of problem where disk logging fails and serial consoles are impractical. Most modern distro has this netconsole as a built-in module. netconsole initializes immediately after NIC cards.

Good news for all hackers. NETGEAR launches Open Source edition of wireless-G router enabling Linux developers, geeks, hackers and enthusiasts to create Firmware for specialized applications

Gzip compression reduces response times by reducing the size of the HTTP response. This document describes gzipping http traffic which can reduces the response size by about 70%. Approximately 90% of today’s Internet traffic travels through browsers that claim to support compression.

This document describes how to get the NetGear WG311 wireless PCI card to work under Ubuntu Linux using Ndiswrapper and wpasupplicant software with WPA / WPA2 encryption.

Linux comes with many serial text and gui based serial communication programs. My favorite is minicom - friendly menu driven serial communication program. If you are addicted to DOS / Windows TELIX (a telecommunications program originally written for DOS and was released in 1986), minicom is for you under Linux / UNIX. Let us see how to configure minicom for my Soekris net4801 Single Board Computer / embedded Linux device.

I’d like to configure my Debian box to backup two remote servers using rsnapshot software. It should make incremental snapshots of local and remote filesystems for any number of machines on 2nd hard disk located at /disk1 ( /dev/sdb2). How do I make backups?

How do I improve my file server performance. I've many large files in directories and how do I speed up access time? The -D option causes e2fsck to try to optimize all directories, either by reindexing them if the filesystem supports directory indexing, or by sorting and compressing directories for smaller directories.