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Building a firewall for a Debian web server

This post addresses how to configure the Linux firewall to protect a Debian-based web application server. While there are GUI tools for the job, we will focus on the command-line tool iptables. The scenario is that you have just installed Debian (or Ubuntu) on a server connected to the Internet. This will be used as a web server hosting your WordPress blog. I assume that you already have Apache, and WordPress installed.

Using double dash to specify pesky command line parameters

Many Linux commands accept command-line options and positional parameters. The grep command searches for a pattern in a given file. Its 2 positional parameters are the pattern and the filename. It accepts options such as -i which specifies that the search is case insensitive. An interesting scenario is when a positional parameter has a value starting with a dash ('-'). This makes the parameter indistinguishable from an option. For example, you try to grep the string -tea in a given file.

Tips on GNOME Classic workspaces

In the world of affordable, dual 27-inch monitors, the GNOME virtual screen feature (aka workspaces) may not hold the same prominent position as before. But, to people like myself who still operate machines equipped with only a single 19-inch monitor, using workspaces effectively is still a big productivity booster. Below are some tips for using GNOME Classic workspaces. Tip 1: Change # of default workspaces By default, the GNOME desktop has 4 workspaces available. The default number can be changed. I, for one, would like to decrease the number of workspaces to 2.

Chrome Remote Desktop connects from your Android device to Linux

Google recently announced the beta release of the Chrome Remote Desktop for Linux. It allows you to remotely connect to a Linux machine from within the Chrome browser. Judging from the early comments in the Google product help forum, setting up the Chrome Remote Desktop on a Linux machine is still rather quirky for certain configurations.

Mix and match stable and testing releases in Debian

My Debian system runs the current stable Debian distribution Wheezy. However, there are software packages that are only available in the current testing distribution Jessie. Examples are dateutils, and Enlightenment 0.17.

How to change window manager for GNOME

If I ask a Linux user what desktop environment he is running, most likely he can tell me the correct answer - GNOME, KDE, Xfce, LXDE, etc. But if I ask him what window manager he is running, I won't be too surprised if he can't answer me. In fact, not long ago, I did not know that myself. The Window Manager dictates how various visual elements - windows, panes, icons, etc - look, and how users may interact with these elements. There are many window manager choices: Metacity, Mutter, Compiz, Openbox, etc.

Hide command from bash command line history

Linux is known as a very secure operating system. But, it is not going to save us if we voluntarily or unknowingly expose ourselves to unnecessary danger. For instance, a password-authenticated command may allow you to specify the password right on the command-line. $ mysql -u root -pMyPassword

Share the keyboard and mouse using Synergy - part 2/2

Part 1 of this 2-part series covers x2x, a nifty software tool that lets you use the keyboard and mouse of one X terminal to control another. If you want to control more than 1 other machine, or the machines are on different platforms (Linux, Mac OS X, and Windows), Synergy is the tool. Installation My primary machine runs Debian 7.5 - aka Wheezy.

Share the keyboard and mouse on two X terminals - part 1/2

I have a desktop and a laptop on my workstation, side by side. No KVM switch. Each has its own display, mouse, and keyboard. I thought I could always slide over to use the other computer. Wishful thinking at its finest. I started investigating KVM options. I like the idea of having both displays visible simultaneously. Therefore, the final solution only needs to share the mouse and the keyboard.

How to resize a picture using command-line tools

Occasionally, I need to resize an image. For instance, Google+ refuses to use my favorite portrait as my profile picture. The reason is that the portrait is smaller than the minimum requirement of 250 x 250 pixels. To scale the image, I can opt for a GUI tool such as GIMP or Pinta. This post explores the scaling of pictures using command-line tools.

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