Best of Technical Support

Our experts answer your technical questions.

Net Radio vs. Downloads

An engineer wants to listen to music over the Internet using a 1MB, two-way DSL connection. Another engineer complains during this session that his downloads are very slow. Now these two engineers want the technician to monitor the network and show the percentage of use of the music and downloads on this Ethernet connection. The technician has Ethereal installed and resolves most problems with this tool, but he finds it a poor performance monitoring tool. I, being the technician, want to know if I am not using Ethereal to its full capability in monitoring the network. Or, is there another tool I can use to perform this function?

George Van Tuyl

A product called the Multi Router Traffic Grapher,, when configured properly and in conjunction with your iptables and other network settings, could provide the data analysis you need.

Felipe Barousse Boué

If you want to use traffic control on your Linux router to balance the need for responsive interactive connections with the demand for fast downloads, check out the “Ultimate Traffic Conditioner” section of

Don Marti

Changing Desktop Environments

How do you change the default window manager on Red Hat? Let me clarify. I log in with text, and when I type startx, it starts GNOME, but I'd like to use KDE.


You can change the content of /etc/sysconfig/desktop from DESKTOP="GNOME" to DESKTOP="KDE" or DESKTOP="WINDOWMAKER", and X will start the corresponding window manager. The file that controls which window manager it starts is /etc/X11/xinit; take a look at it.

Felipe Barousse Boué

Hardware Specs for Laptop?

I am attempting to load Red Hat 7.3 on a Sony VAIO notebook, model no. PCG-GRT 250P. I need to know what horizontal and vertical sync values must be entered for the LCD screen.

Noel Haynes

From what I have found, your VAIO should have a horizontal range of 27–115 and a vertical range of 50–160. My last suggestion would be to install, say, Fedora Core 1 instead of Red Hat 7.3, which has newer X versions. I do not own a VAIO, but in looking around I found this page that may be a good reference for you: The page links to configurations for many laptop models.

Felipe Barousse Boué

Displaying an Image in an X Application

I'm working on digital image processing on Linux. I have read a .bmp image successfully. Now I have to display the image using X11. I have used XCreateImage() and XPutImage(), but the figure is not being displayed. I feel the problem is with the arguments I pass to these functions. How do I do it?


Try using the sample code from this X tutorial:

Christopher Wingert

Encrypted Cross-Platform Remote Desktop?

Does Linux come packaged with something similar to Windows 2000 Advanced Server's Terminal Services? I have a Windows XP workstation that needs to be configured to have remote access to a Linux server's applications. The connection would be over the Internet—a VPN, perhaps?


Yes, there is a cross-platform remote desktop solution. VNC for Linux and Microsoft Windows is available under the GNU GPL from RealVNC (, and there may also be VNC packages available for your Linux distribution. If your distribution supplies a VNC package, you should probably use it so that the software will be easier to update if necessary. See the RealVNC FAQ for how to encrypt a VNC session using SSH.

Don Marti

Mysterious Freezing Hardware

I recently purchased a new computer for the boss, an AMD 2500+ with a Biostar M7NCG motherboard, 1.5GB of RAM and two IDE hard drives. After a couple of months, it began freezing once or twice a day. No single application is to be blamed. I've tried replacing hardware and even went so far as to put the hard drives in a totally different computer, which did not resolve the issue. What are the best ways of troubleshooting such a problem?

Leroy Powell

First, this looks like a hardware problem, not necessarily Linux-related though. Without specifics, it is hard to guess what is going on. Let's suppose you have Linux in it, then when you say “freezing”, is it the whole machine that freezes or only the graphical user interface? Those are quite different situations. I'd first look at the system logs. If it is the whole machine locking, probably switch memory banks, take some memory out and try the system. If the GUI is what freezes, I would inspect the video card. Also, check for the latest drivers, or a newer Linux distribution may solve your problem.

Felipe Barousse Boué

I hate to say it, but in a business, a PC that's out of warranty and has an intermittent problem is worth less than the time required to diagnose it. Assuming your boss pays you a fair wage, he's better off buying a new box with a longer warranty. Put this time-sucker out on the sidewalk.

Don Marti

Binding a Key to Send a Signal

What should I do to generate a SIGHUP signal when I press Ctrl-K?

Narayanan Iyer

You can use the bash bind command to assign certain behavior to key sequences. The .inputrc file is related as well. Do a help bind from within bash or see the “shell builtin commands” section of the bash man page for further information. Take a look at for more information, or go to for a hot key creation tutorial.

Felipe Barousse Boué