Get the external IP of your router on the command line

Sometimes you want to write a script that needs the external IP of the router your client is connected to. Here are three possible solutions.

UNIX Tutorial for Beginners

A beginners guide to the Unix and Linux operating system. Eight simple tutorials which cover the basics of UNIX / Linux commands.

Getting started with awk

This qref is written for a semi-knowledgable UNIX user who has just come up against a problem and has been advised to use awk to solve it. Perhaps one of the examples can be quickly modified for immediate use.

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How to use pkg on OpenSolaris for Package Management

Opensolaris 2008.05 ships with the IPS Image Packaging System, which, even if it’s got very few packages, has both command line and gui tools. The following tutorial goes over how to search for an installed package, check for updates for a package, search for and install new packages, add repositories, and how to update the entire system. Enjoy.

Rescuing files from lost+found

The lost+found directory included in (Unix) file systems is usually empty. Only used when fsck doesn't know what to do with files that have lost their place in the file system, they stand as a temporary holding place for those rare instances in which fsck can't put everything back together after file systems have become corrupt in some way. If you see files in lost+found, you can expect them to look rather unusual.

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Sun launches OpenSolaris "2008.05" under CDDL

Sun Microsystems officially launched OpenSolaris (OS) today. Available pre-built as a combo live/install CD, the initial binary distribution download of the OS features a GNOME user interface, highly fault tolerant ZFS root filesystem, IPS package managment, and "DTrace" tuning tools.

Sun ships OpenSolaris, takes on Linux

A mere three years after starting the OpenSolaris project, Sun Microsystems today releases the first official OpenSolaris version. OpenSolaris includes the all-important Project Indiana, a project from Debian founder Ian Murdock to make OpenSolaris’ package management system more like that of Linux. OpenSolaris is based on the original Solaris kernel but includes features such as the Zettabyte File System (ZFS) which offers a range of tools including instant rollback and checks to prevent data corruption.

OpenSolaris is widely being seen as a competitor to the rival Linux open source operating system. One of the main reasons for this is the inclusion of Murdock’s Project Indiana, a software packaging system that simplifies the installation and integration of third party applications.

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Detect intruders on your network with Snort

Snort is a Network Intrusion Detection System (NIDS), which can view and analyze packets on a network to determine whether or not a system is being attacked by remote.

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OpenSSH Speed Tips and Tricks

Although using public key authentication instead of passwords is a great method for increasing the security of SSH transfers, transferring SSH identity keys can be a royal pain. First, you create your key pairs; then, you copy the public key into the correct locations on all the machines you want to log into. The keys must be in a particular format, and you must go into the correct directory with the correct permissions.

Fortunately, ssh-copy-id, a slick utility included with OpenSSH, makes it easy.

Lsof

lsof is the Linux/Unix über-tool. I use it most for getting network connection related information from a system, but that's just the beginning for this amazing and little-known application. The tool is aptly called lsof because it "lists open files". And remember, in Unix just about everything (including a network socket) is a file.

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Unix Cheat Sheet

This document is a collection of Unix/Linux/BSD commands and tasks which are useful for IT work or for advanced users. This is a practical guide with concise explanations, however the reader is supposed to know what s/he is doing.

Monitoring a slow system

When your UNIX® system runs slow, it is vital that you discover what the problem is as quickly as possible so you can get your system back into the normal operating mode. There are many causes for a slow system, but actually identifying the problem can be exceedingly difficult. In this article, study examples of how to identify and diagnose the cause of your slow running UNIX system to get your machine running properly again.

Network scanning

Discover how to scan your network for services and how to regularly monitor your services to keep uptimes to a maximum. A key way of ensuring the security of your network is to know what is on your network and what services individual machines are at risk of exposure. Unauthorized services, such as Web servers or file sharing solutions, not only degrade performance, but others can use these services as routes into your network. In this article, learn how to use these same techniques to ensure that genuine services remain available.

Disabling services in Solaris 10

To disable a service you have to be root or have a sudo...

The crossover LAN

You have probably heard that a two-node LAN can be configured by stringing a crossover cable between the network ports on two systems. Not only is this true, but it's not all that hard to do provided you have a few tools, a length of CAT 5 cable and a couple RJ45 connectors. Using a crossover cable has one decided advantage over a traditional network hookup -- it avoids the requirement that a hub be used to connect the two systems, saving both money and rack space.

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Secure PHP installation on unix/linux systems

With the growing concerns regarding comment SPAM, XSS attacks, security breaches, etc, we should spend some time learning how to defend ourselves against such threats.
We already know everything about input validation, code and SQL injection attacks, error logging, vulnerability scanning, etc., don't we? ;-) So, let's focus on securing our PHP server, thus barring most of the attacks from the start.

MIT Releases Source of MULTICS

This is extraordinary news for all nerds, computer scientists and the Open Source community: the source code of the MULTICS operating system (Multiplexed Information and Computing Service), the father of UNIX and all modern OSes, has finally been opened.

serving more UNIX GUIs with VNC at the same time

There is an easy way to access your Linux's GUI: VNC.

Linux or UNIX password protect files

using mcrypt or openssl commands.

introduction to awk

Awk may sound funny but actually it is an extremely powerful command line tool. Awk or variations of awk (gawk, nawk) can be found on most modern linux & unix distrobutions by default. Awk can be used as a programming language which can nearly turn text files into something more like a database. I am not going to elaborate that extensively on the awk programming language. This article will be addressing many uses for the awk command. Hopefully by the end of this article you will be confident using awk in your day to day command line adventures.I use the awk command for all kinds of things such as trimming down output, restructuring output, & mathmatical computations.