But for those who only need to monitor a few devices, configuring Nagios to do so is actually quite simple. In this article I am going to show you a few configurations to handle and then how to add devices and checks for your installation.

Post-install configurations and plugins

Before you get busy setting up devices for Nagios to monitor, you should first install some extra plugins for the system. Open up Synaptic, search for “nagios” (no quotes), mark nagios-plugins-extra for installation, and click Apply to install. Once that is done you will already have more functionality with Nagios.

Now let’s take care of a couple of configurations. The first is in the /etc/nagios3/conf.d directory. The file is called contacts_nagios2.cfg. In this file you will configure who is to receive the email alerts. The line to set this configuration is:

email    root@localhost

You will want to change that email address. That is it for this configuration file. Now in order for Nagios to be able to send out alerts via email, the machine housing Nagios has to be able to send those alerts out. You can check that by using the mail command like so:

mail email@address -s TEST

Where email@address is an actual address you can use for testing.

Once you enter that line, hit Enter and then type some random text. When you’re done typing hit <Ctrl>d and then Enter. The mail should send away. If not you will have to troubleshoot your mail server (beyond the scope of this tutorial).

Add a device

Figure 1

Now for the good stuff. We are going to add a device to Nagios. The device we will add is a Windows XP desktop to monitor. Within the /etc/nagios3/conf.d directory you will see a number of .cfg files. These are the files Nagios uses to dictate what is see and how it acts upon what it see. For every device you want to use, I find it best to add a .cfg file. So let’s create the file /etc/nagios3/conf.d/windows_xp.cfg. The contents of this fill will look like what you see in Figure 1.

As you can see there are a few directives here. The directives are as follows:

• check_command – The command used to check the status of the device.
• max_check_attempts – How many times will Nagios retry the status check.
• check_period – How often are the checks made.
• process_perf_data – Enable the processing of performance data.
• retain_nonstatus_information – Enable the retention of non-status information across reboots.
• notification_interval – How often are notifications sent to inform the administrator this host is not okay.
• notification_period – How often are notifications sent out.
• notification_options – The options shown are w – send notifications on “warning” state, u – send notifications on “unknown” state, and “r” – send notifications when a service stops flapping (when a service changes frequently).

NOTE: Depending upon the version of Nagios you have installed the notification_options will be different. Some instances will not accept the “w” option. If you get an error, exchange “w” with “d” (for down).

As you can see there are configuration options that will be specific to your devices and networking topology (host_name and address are examples). Once you have created this file save it and restart Nagios with the command sudo /etc/init.d/nagios3 restart command. Now take a look at your Nagios page and you will see the new device you just added.

Final thoughts

Someday someone will come up with an automated way to detect devices in Nagios. Until then we are relegated to adding them using this means. Does that mean you should shy away from Nagios? Not at all. Nagios is a powerful tool ready to help network administrators keep tabs on their network devices.

But why would you want multiple desktop wallpaper? It seems like nothing more than aesthetics? To many that is true – but for some power users it can make it quite obvious what desktop is for what job. I am one of those users that prefers to work with multiple desktops. It just makes work so much more efficient. But when you’re using Compiz (and why shouldn’t you be?) Setting up multiple wallpapers isn’t as simple as adding a new wallpaper to your existing configuration.  In this tutorial you will see just how to set up Compiz to work with multiple wallpaper.

Assumptions

The first of these assumptions is that you have Compiz working and the CompizConfig Settings Manager installed.  The second assumption is that you are using the GNOME desktop environment (for this article I am using GNOME 2.28.1. The final assumption is that you have no need for desktop icons. With that out of the way, let’s get to the configurations necessary.

Compiz

The first configuration is in the CCSM tool. You will find this tool in the System > Preferences > CompizConfig Settings Manager. When you fire up that tool enter “wallpaper” in the search field. The Wallpaper settings is listing under Utility. When you see it listed click on it to open up the options.

Figure 1

As you can see (in Figure 1)  there are only two sections to configure. The first is to click the checkbox to enable the Wallpaper for Compiz. The second is to add Wallpaper(s) by clicking the New button, navigating to where you have your images saved, selecting your wallpaper, select your Fill Type (do you want the image centered, scaled, etc), and click Close.

When you have that done you can close out CCSM. If you check you will still see only one wallpaper. What gives? You’re not done. Now it’s time to fire up another tool – gconf-editor.

Gconf-editor

Figure 2

Hit <Alt>F2 and type gconf-editor to open up this tool. You need to navigate to Apps > Nautilus > Preferences (see Figure 2) . Scroll down until you see the show_desktop entry. If that checkbox is checked, uncheck it and close the tool.

Figure 3

Now check your desktop. How many wallpapers do you see? As many as you added in CCSM? That should be the case. Hopefully you can see (in Figure 3) the two different wallpapers I have added to my desktop.  Of course I also have a few other features enabled in Compiz, but you get the idea.

Don’t forget to remember how many workspaces you have enabled. Although you don’t have to add as many wallpapers as you have workspaces, you don’t want to add more wallpapers than you have workspaces.

Final thoughts

I hope you can see how this little addition can make work a little easier. Create a specific wallpaper for administrative work, put it on a specific workspace, and only do your admin work there. It’s subtle, but effective.

I really can’t see Microsoft adding it into Windows itself, not even for Windows 7, so I’ll have to keep looking around for decent freeware alternatives.

The annoying thing is that as of yet, I haven’t really found any decent desktop managers which are simple, stable and perform well.

Today however, I found one which I really liked the look of on CodePlex.

Multiple Desktops for XP and Vista is a alpha quality desktop manager which you can try out here, but is pretty unusable right now. What I liked about it is the simplicity, ease-of-use and generally good design. Using the new Windows Vista live thumbnails it can give “give you a full screen preview of all of your desktops.”

At the moment however it’s slow and buggy, but I shall be keeping an eye on it for upcoming versions.

The full set of features includes:

• An infinite number of desktops only limited by the amount of memory in your computer
• A full screen desktop/window manager/switcher
• Live Vista thumbnails of all of your windows
• An alpha-blended indicator window to provide a visual indicator when you switch between desktops
• Hotkeys for up to 9 desktops using your numpad keys along with "send window to desktop" hotkeys
• A system tray icon to access a menu containing items for every desktop, no matter how many
• Multiple-monitor support
• Arrow key hotkeys
• One system tray icon per desktop (optional)
• Window-specific menus
• Sticky windows to exclude windows from the virtual desktop manager
• Per-desktop backgrounds
• XP support
• Thumbnail window tool
• Show all windows hotkey
• Show mini-preview at cursor hotkey
• Program rules for locking programs onto desktops
• Command line arguments for launching programs onto desktops, switching desktops, and showing the switcher

You can check it out here.