Harry Seldon's blog

Fractals, Chaos, and Control Systems on Rails


Wifi on Intrepid

Posted by Harry Seldon on December 18, 2008

For one year, I have got plenty of troubles with the wifi under Ubuntu. I even got some troubles when I migrated to Intrepid Ibex. But I am pleased to say that finally the wifi management seems much better under Intrepid than under the previous versions.
To solve my troubles I just needed to clean the interfaces file, to reinstall the packages network-manager and network-manager-kde. Recently, I switched of wifi network and it worked smoothly. Amazing !
However, I still do not know how to freeze the IP address. If you have an idea please leave a comment !

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Wifi on Linux

Posted by Harry Seldon on August 08, 2008

I installed Kubuntu Feisty about one year ago. That was my first Linux installation. Since then I got plenty of troubles with my (pci) wifi card a WMP54G with a ralink rt61 chipset. But the most surprising is that each time you update the ubuntu version you need to setup again but differently your wifi network. My first advice is use a wirewith connection as much as you can. My second advice is if you have a rt61 chipset just change it. A wireless card is not that expensive. I should have done that one year ago, I would have avoided many troubles. Under Feisty Fawn after some work the wifi was perfectly working in wpa. With Gutsy Gibbon it was working ok but only in wep. And with Hardy Heron, it is working in wep but I still have some weird problems. The wifi card does not wake up from suspend ot hibernate and if my router is rebooted I cannot connect. In all cases I need to reboot. Here is my configuration.

In my current configuration I have uninstalled networkmanager or wicd. My /etc/network/interfaces file has :

  auto ra0
  iface ra0 inet static
  wireless-essid myssid
  wireless-key 0000000000

To solve the wifi loss on hibernate problem I tried to add “rt61pci” to the MODULES_WHITELIST in /etc/default/acpi-support file :

  # Note that network cards and USB controllers will automatically be unloaded
  # unless they're listed in MODULES_WHITELIST

  # Add modules to this list to leave them in the kernel over suspend/resume

It had some effect. Now the wifi card is alive (connected to the local network, ip ok) after standby however internet connection still does not work. In case you need to know the name of your wifi module you can use the command :

  sudo lshw # lists your hardware and the drivers used.

From this bug report it seems that installing the linux-backports-modules-hardy-generic package should help. That will be my next step.

By the way here is a list of useful commands to configure your wifi on Linux :

  lsusb # USB hardware list
  lspci # PCI hardware list
  sudo lshw -C # network network hardware list
  lsmod # loaded modules list
  iwconfig # wifi interfaces list
  ifconfig # network interfaces list
  iwlist # list of the networks that can be scanned by the wifi hardware
  cat  /etc/network/interfaces # gives you the content of the interfaces file
  cat /etc/lsb-release # gives the Linux version you are using
  uname -r -m # gives the Linux kernel you are using
  sudo ifdown ra0 # stops the ra0 interface 
  sudo ifup ra0 # starts the ra0 interface
  sudo /etc/init.d/networking restart # restarts your network interface

This list can also be found in French here .

Here is a short list of wifi managers.
network-manager, knetworkmanager, wicd, rutilt, kwifimanager, wifi-radar.
I tried all of them. Wicd proved to be useful in my case even if I am not currently using it. I am still using kwifimanager only to display the state of the connection, it does not configure anything.

I hope you got less troubles with your wifi setup.

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Give 2 monitors to your PC

Posted by Harry Seldon on August 06, 2008

Please, if you are an employer give 2 screens to your employees’ PC.

Why ?

You gave your employees a nice dual core PC with 2 Go of RAM and 80Go hard drive. Once you are there you already have 2 PCs : 2 processors, Twice 1Go of RAM, and twice 40 Go hard drive. So the natural next step is 2 monitors. Even more, the video card has probably 2 video outputs. So it is easy to add a new monitor. OK you are telling it is expensive. Well is it ? A flat screen is what 200 € nowadays ? Not convinced ?

Ok let us see why it is actually useful.

Today, email is a new phone. You use it to discuss with someone, to get info, to ask info to several people at the same time, along the day you keep an eye on your mail client just like you stay available to answer a phone call. When you answer a phone call you still have your monitor in front of you and it may prove very useful. You have a phone on your desktop so you should have an email client on your desktop. This email client is your second monitor.

“Email is a loss of time I am definitely not going to let my employees loose yet more time with email!” OK you want your employees to be productive and as efficient as possible. Here is another use of the 2 screens. I am a control systems engineer so I make a lot of technical work including simulations and data analysis under Matlab/Simulink. It happens that I must report about this fun stuff. So I write technical notes under Word. The notes make heavy use of Matlab figures / data. So I must send the data from one to the other. I click on Matlab, it appears and Word disappears. I click on Word it appears, etc. What I want is 2 monitors, Matlab on the right, Word on the left. It is as simple as that. Moreover I can type my report and check what is going on for other simus.

In financial engineering people use commonly more than 2 monitors to follow the stocks. Even if you are in a less profitable business I am sure it will be worth it to buy 2 monitors per PC.

It is so frustrating to have 2 or 4 processors on your PC and yet only one monitor. I will end up installing by myself 2 monitors because if I wait for my dear employer I will wait for long.

By the way if you have only one video output on your card just buy a "video splitter".

You already have 2 monitors or more ? Tell us your setup !

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