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 Post subject: [One][Ice][Two] WiFi Troubleshooting Part 1:Getting Sys Info
PostPosted: Thu May 27, 2010 3:30 pm 
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Joined: Thu May 20, 2010 8:56 am
Posts: 2132
Note: This tutorial does not cover everything wireless, it's already mad long. It deals with WiFi only. 3G and Bluetooth will go up elsewhere.

Class: Generic wifi problem resolution tutorial
Difficulty: Situational, depending on hardware compatibility
Time: Situational, depending on hardware compatibility
Desirability: Essential if wifi doesn't work 'out of the box'

Linux, Peppermint OS and wifi Networking

Native Linux wifi drivers are under active development by the Linux kernel's IEEE-802.11 subsystem team. The Linux kernel which comes with Peppermint OS comes with these built as kernel modules which are dynamically loaded when the kernel detects a wifi device on the system.

This should mean, in the majority of cases, that wifi will work 'out of the box' on Peppermint OS.

This document, though, and its more advanced sequel, are intended to provide guidance and support to those for whom this is not the case. It may also prove useful to those considering purchasing a new wifi device.

They are potentially overwhelming to someone who has just begun using Linux, or anyone for that matter ;) Wireless networking is complex and the networking board on these forums is there for a reason. It is best to ask rather than blindly follow instructions that aren't properly understood, or make pseudo-random decisions. If in doubt, ask.

That said, the writer hopes that most users will be able to follow this first part, which concerns getting information from the computer ("Research before diagnosing..."). Obtaining this information so that it can be posted with a support request will be appreciated by everyone and increases the chances of the help you receive being useful.

Armed with the information from this part, the user is encouraged to post their problem on the networking board. Those more confident in their experience and abilities may be interested in continuing on to the more advanced second part, which goes on to follow a systematic procedure to try to diagnose and resolve the problem.

Click here to advance to the second part.

Resources available online

There are specialist computer hardware stores online which cater for Linux operating systems, and who will only advertise and sell wifi equipment that is known to work with Linux. If purchasing a new wifi card or a new computer with onboard wifi capabilities, it may be worth researching these stores even if the hardware is to be purchased elsewhere.

Ubuntu community documentation includes a list of wifi cards that have been tested on Ubuntu.

The IEEE-802.11 user page links to support resources, driver information and downloads, and documentation.

Research before diagnosing, approaching these sites and/or asking for help

It is helpful to be informed about the wifi device in question before seeking documentation and support. Even if the brand name of the device and a model number are known, it is still best to obtain information on the actual chipset from the device itself. This is because manufacturers are known to change between chipsets, sometimes even on the same brand of device.

The commands to obtain this information vary slightly depending on the type of hardware in question.

For onboard devices, the lspci command should be used.

lspci | grep Net

This command runs lspci (which displays an inventory of all onboard devices on the computer), and pipes the output to grep which only displays lines including the word "Net" (as in "Network Controller"). If the grep command narrows the list down too much (i.e. no device is listed when there is one present), simply remove it and the pipe (|).

For PCMCIA devices, you will need to have downloaded and installed the pcmciautils package. If obtaining this package from an alternate source, it has no further dependencies to be met on a default Peppermint OS install and may be downloaded alone. The command to list pcmcia devices is


For USB devices, the lsusb command should be used.


Some USB wifi adaptors are not properly identified (i.e., no name is mentioned), so it is better not to use any filter. It should be quite clear which usb device listed is the adaptor, by name or by deduction. Perhaps more important than the words used to identify the device is its USB device identifier number, which is the series of eight characters split into two sets of four by a colon. This identifier can be entered into Google, which very often returns page hits providing information and support for Linux distributions. Searching for my device brings up these links, for example. The very first link to the Debian wiki correctly identifies the driver my device needs.

Armed with information on the model of adaptor, the Ubuntu list and's devices page may be referred to determine which kernel module (driver) should be loaded.

This may then be cross-referenced with the lsmod command. lsmod lists all of the modules loaded into the kernel at the time it is executed.

lsmod | grep rt2870sta

This command returns, on my computer,

rt2870sta             461811  1

showing that the module has been loaded. If the command returns nothing, this means that the module is not loaded, and might be a first indicator of the root cause of the wifi problem. Running lsmod on its own returns every module that is currently loaded into the kernel. It is a good idea to run this if the expected module has not been found, as a somewhat common problem is that the system is loading in the wrong or conflicting modules instead of the one needed by the device.

Two useful commands in diagnosing or preparing to post a support request are ifconfig and iwconfig. These commands, run with no parameters or options, both output information about the system's network connections. Ifconfig returns information about every network device on the system, while iwconfig only returns useful information about wireless (and "no wireless extensions" for non-wireless devices). These commands are helpful for identifying the name the device has been given by the system (e.g. wlan0, ra1, ath2...), MTU, frequency, bit rate, link quality and so on. It is likely that a user posting for help will be requested to post the output of these commands if the problem is at all complex to resolve.

Additionally, these commands also provide direct control over the network subsystem. It is worth emphasising that ordinarily it should not be necessary to use these command line tools to control network devices, since Peppermint OS is packaged with a network manager designed to handle these functions automatically and through a GUI. However, two very basic commands:

sudo ifconfig ra0 up
sudo ifconfig ra0 down

send instructions to enable and disable a network device (in this case the one named ra0 by the system) respectively.

A final command that may prove useful to users troubleshooting wifi network problems, whose devices work but are unable to associate, is iwlist.

iwlist wlan0 scanning

will tell the device named wlan0 to scan on all channels for available association points and return information on them (address, mode, encryption, and so forth). This is not a tutorial page on iwlist, and further information is available through iwlist's man page

man iwlist

and online.

Post and Attempt to Resolve

At this stage users are invited to post technical information and a description of their problem to the networking board, or continue to the advanced tutorial.

Click here to read the advanced tutorial.



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