Wireless Networking

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Linux Wireless Network Issues

Unfortunately, most Wireless card makers and even the chip makers who make many of the integrated circuits used in the wireless adapters are not releasing programming information for how their cards and chips work. Many manufacturers are also only releasing software drivers for their products for the Windows operating systems. That has caused problems and delays in Linux's support of wifi devices. If the software developers who do networking support for Linux had good programming spefications for these devices we would not only have good drivers for them, but would likely also have software that can use them for other interesting and unique applications, since there seems to be a lot of software control of these programable radio devices.

Some software drivers have been released for some devices. Occasionally a manufacturer may even claim the driver is "open source", but the source code is not available and the driver that is available is released only as a pre-compiled module. Often these drivers are unreasonably large and their size would prevent many of them from being incorporated into the Knoppix CD.

With the above said, Knoppix is improving in it's ability to detect and support wireless devices. If the device you own does not work with the ciurrent Knoppix release, be sure to check it as future releases come out.

For cards where there has only been a Windows driver released, another approach that has been tried is to use special translation software that will allow software drivers written for Windows to run in the Linux operating system. This translation software is named ndiswrapper. With ndiswrapper you can attempt to load a driver written for Windows and run your card under Linux. Recent versions of Knoppix do include ndiswrapper, but they do not include the Windows drivers, so you will need the Windows driver for your device to try to use this approach. Some users have had good results with ndiswrapper, other times the Windows driver will not work with it. There is a list of cards and drivers that are reported to work with ndiswrapper at http://ndiswrapper.sourceforge.net/mediawiki/index.php/List

Linux support for wifi equipment at this time seems to be much better for PCMCIA (PC) cards and for PCI cards than for USB devices. USB adds an extra level of complexity, and USB isn't really well suited for networking, even though this equipment is widely available. Users would be well advised to select types of network interfaces other than USB. Also, the support there is tends to be better for older 802.11b equipment than 802.11g and newer equipment, but 802.11g support is reported to be improving.

Still, there is another major setback for Linux wifi drivers, and even some newer wired nics as well as likely other hardware: manufacturers are starting to include firmware not on the card but in the driver to be downloaded to the card at boot time. The good part of this is that the firmware can be easily updated. There are many bad parts though, the key one here being that the official drivers are only released for Windows and the manufacturers will often not allow the copyrighted firmware to be included in a Linux 3rd party driver. So now developers have a new major hurdel to overcome, not only figure out without documentation how to interact with the NIC, but also how to write firmware for undocumented hardware and perhaps an unknown instruction set. There have been several articles on this recently, you can find one of them at http://www.thejemreport.com/mambo/content/view/293/ . The bottom line is that hardware that takes this approach and doesn't support Linux on it's own is unlikely to be supported by the developer community in the future. Don't buy the wrong stuff and then complain about this or say negative things about Linux because you bought proprietary Windows-only hardware. But, alas, some vendors seem to put "Linux" on the packaging, without making any support available. Perhaps they have heard of ndiswrapper? This spoils things for everyone: all you can do is check on the web. Support vendors who genuinely support Linux.

Wireless Networking Security Issues

When running a wireless network, you should be aware that your system is more vulnerable to attack than with a wired network, and that information that you send may be seen by others. Other computers on the wireless network, even computers on wired connections, may be attacked by someone coming in on the local wireless network, and these attacks are not prevented by incoming attack blocking in your router. Also users often have local firewall rules set up to treat attackers who show up as local addresses as "trusted". Attackers to your local network may send spam from your connection, may search your system for banking and other financial information, or may plant viruses and back doors to give them remote control of your system later.

This article is only an overview and readers are encouraged to read their equipment manuals, and use Google and other Internet resources to read further on the concepts mentioned here if they are not already well aquainted with them.


A common and important security concern is to encrypt the network. With encryption enabled, others cannot connect to your network unless they have the same security key set in their equipment. And they can not look at packets that you transmit and easily see private information in them, such as passwords or bank information. The first standard for wireless encryption was called WEP, which stands for Wired Equivalent Privacy. WEP is still in wide use today and is the only encryption available on some 802.11b equipment. Unfortunately, due to some design flaws, WEP can be easily cracked. While some estimates claim that it my take capturing data for up to 24 hours before a hacker has enough data to crack WEP, there have been many demonstrations where it has been cracked in even far less time. WEP should be considered a "better than nothing" approach, but not much better. WPA (Wifi Protected Access) and WPA2 are now considered better encryption systems. They gain their improved security by automatically changing the keys used as wifi packets are exchanged. Still, no Wifi system should be considered completely secure and users should always pay extra attention to network security and take extra precautions when using wifi. Don't set your software firewalls to make all local IP addresses trusted, for example. And be alert to extra network activity. Some users even run an application on one computer on the local network that watches for new connections and alert the owner when any new network activity is seen.

MAC address control

Many wireless routers have a feature that limits wireless access (or all access) by the hardware MAC address built into the network cards. While this may help improve security to a small extent, be aware that any determined hacker can send you packets with a MAC address that you trust in them. And understand that if a hacker can watch your packets and pick out passwords, banking info or other private information from them, they do not even need to send anything into your network to compromise your wireless system.


Routers often have a feature that allows then to not broadcast the SSID or network ID that distinguished one network from another. This has led some poorly informed people to advise others to turn off SSID broadcasts to "make their networks more secure". This does not secure your network in any way, the SSID is still sent in all packets on the network and can be quickly determined. Turning off SSID broadcast can actually have a negative effect on your network.

Router passwords

Most or all routers have a web interface and software setup feature. Access to this feature is controlled by a password. The default values for these passwords are well known by hackers (they are sometimes even blank) and you should always change the password to some secure password (don't use common passwords such as a pet's name). It is easy for a hacker to see what type of router you have and try to gain access by default passwords and other known exploits. If a hacker can gain access to your router they can do a lot of additional damage, including deleting logs that show any trace of their activity, or even locking the owner out of their own network.

Additional information

Unfortunately, many wireless routers are run in default unsecure modes. Hackers known as "wardrivers" can often drive around neighborhoods and find more than half of the routers in a neighborhood are wide open. And there are many cases of people accidentally connecting to the wrong network because both neighbors used default settings on their equipment. It is a very good idea to secure your network, both to discourage the casual wardriver (who will likely just move to an unsecured system) and to prevent accidental use by a neighbor that might get you into trouble with the RIAA or MPAA or your own ISP.

When first setting up a wireless connection in Knoppix it can be handy to disable WEP or WPA encryption if this is reasonablly safe to do so at your location. After you get networking working without encryption then enable encryption on both ends and get that working. But never leave the network encryption disabled for extended periods of time. And for improved safely, it may be wise to shut down or disconnect from the network all other computers on the network, wireless and wired, until encryption is re-enabled.

It should aso be apparent from the above discussion that if you access your e-mail from a wireless "hot spot" such as at a coffe shop or an airport terminal, that hackers can be watching and learn your account name and password. Making on-line purchases, doing on-link banking or other activity that exposes private account information is also extremely dangerous when using any wireless network.

General Information On Wireless Card Setup Under Knoppix

This is a stub for this section, to be added shortly NdisWrapper: This seems to be a way many people are useing windows drivers to run their wireless equipment. This is done to allow Linux to talk through a wrapper that emulates windows calls to the windows driver. It asks for the driver X.inf and maby X.sys Then 2 other things ...id and wep key.

If instructions of what to enter into these fileds and where to find it and what version of knoppix the GUI interface being used is found and maby a genaric BA shell interface for doing this.

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Short and sweet (but incomplete)

ndiswrapper -l (lists all the present drivers)

ndiswrapper -e (do for each driver)

modprobe -r ndiswrapper (unload old module)

nsidwrapper -i mywindowswirelessdriver.inf

ndiswrapper -l (my.. is there only one there? :)

modprobe ndiswrapper

dmesg | grep ndis

iwconfig (Gottcha!!! wlan0)

ifconfig wlan0 etcetc

iwconfig wlan0 etcetc

dhclient wlan0

ping google.com

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My two bits of information added here could be edited for readability but I definitely believe it will help people (it helped me!)...

Here's one example of how to use ndiswrapper (http://ndiswrapper.sourceforge.net[1]) READ the Install directions (at least twice) until all the commands and the REASON you're typing these things in makes sense because you may have to modify it for your particular situation (as I had to do) AND read Troubleshooting if you have troubles.

Note: My wireless usb hardware was listed under List of cards known to work, this may make redundant the section below.

Copy the whole folder (you definitely need the .inf and the .sys file but maybe .cat or .dll helps too) with the windows drivers (e.g. DRIVERS containing DELLNIC.inf and PRISMA02.sys)

UHHH... check that, you actually first need the drivers for the Motherboard USB Controller (ah Knoppix how could you let me down? :) in this case: Silicon Integrated Systems Winxp/2k drivers for usb 2.0

Go into root shell (not just terminal console)

Type 'lspci' at the prompt to see a listing of USB bridges (the way usb devices get to the motherboard). Look for your USB controller (e.g. 00:03.0 USB Controller: Silicon Integrated Systems [SiS] uSB 1.0 Controller (rev 0f) etc.

type: ndiswrapper -i filename.inf

Hint you might have to type

ndiswrapper -i /home/knoppix/tmp/DRIVER/DELLNIC.inf

or first I learned I had to install

ndiswrapper -i /home/knoppix/tmp/SiS/SISUSB2X.INF


ndiswrapper -i /home/knoppix/tmp/SiS/USB2X.INF

I then tested it:

ndiswrapper -l

which showed me 'driver invalid' (But the USB was finally ok) so I had to remove the old one (which also included browsing with root privileges to /etc/ndiswrapper and deleting the dellnic folder)

ndiswrapper -r /home/knoppix/tmp/DRIVER/DELLNIC.inf

then again type (actually for insurance I rename DELLNIC.INF to dellnic.inf):

ndiswrapper -i /home/knoppix/tmp/DRIVER/dellnic.inf

then finally:

ndiswrapper -l

showed me dellnic: driver installed device (413C:8104) present

I tested it and

modprobe ndiswrapper

came up without any response (before it gave me some crappy error) but futher investigation

dmesg | grep ndis

gives me ndiswrapper version 1.32 loaded... ndiswrapper: driver dellnic (...) loaded usbcore: registered new interface driver ndiswrapper

Now that we've installed the hardware we've got to get the software working...


shows me wlan0 is already setup! Notice the interface name is wlan0, so you should issue the following command to associate to your

nearest (unprotected, unencrypted) access point:

dhclient wlan0

BUT in my case I need to start WPA Supplicant (necessary to use WirelessEncryptionProtocol)? At least Knoppix button -> KNOPPIX menu -> Network/Internet -> Wireless LAN Kwlan does a lot of the work but is incomplete - it doesn't have a quick gui to configure the WEP and everything so...


shows me how my wireless is working (IEEE, ESSID, Mode, Freq, AccessPoint, etc.) but it doesn't configure anything by itself... instead:


starts a set of gui prompts which will configure my wireless: ESSID (network name/id) type in name NWID (cell identifier?) left blank Mode left blank (defaults to Managed) channel number left blank (defaults to auto) frequency left blank encryption key . . . . . .

additional paramaters? iwspy iwpriv

Which is close - but now I need an IP (since my AccessPoint does DHCP),

pump -i wlan0

gives me an ip address! All finished.

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The below sections are specific information on specific make and models of Wireless Networking Adapters and information we currently have on if they are supported in Knoppix or not. Please add your results with your card to the list, and please try to keep the list in alphabetical order. Please do not post questions about wireless adapters here, those should be submitted in the Networking Forum.


Belkin 802.11b 11Mbps PCMCIA card F5D6020

This 802.11b pcmcia card (pc card) was detected by Knoppix 3.7 (maybe by prior versions too), but I could not get it to operate properly. Starting with Knoppix 3.8.1 it was detected and worked perfectly. ndiswrapper is not needed. My card is marked ver. 2101 on the box. If your card is not ver. 2101 it may or may not use a different chip set.


Here is a link to a D-link page that claims to tell you which D-link cards have "open source" drivers and which do not.


However, it is worth mentioning that in most or all of these cases the drivers are not really "open source", they are precompiled modules that the source code is not available for. And in some cases they are insanely bloated, the "driver" for my card is about 2 megs in size just for a driver! Note that not all of these cards are supported by Knoppix and it is extremely unlikely that even if the license permits it that a sepcific card driver will ever be included in Knoppix if it is several megs in size.

D-Link DWL-650

This is a very common and inexpensive 801.11b pcmcai card offered by D-link. Unfortunately, D-Link has actually released a number of different versions of this card that use completely different chipsets from different intigrated circuit manufacturers all under the same model number. The D-Link website can be used to identify which version you have, but the version number may not be marked on the outside of the box when you buy this card, so it may be a problem to find one that works under Knoppix.

There are reports that some versions of this card are detected and work under Knoppix. See this thread in the forums: http://www.knoppix.net/forum/viewtopic.php?t=19759&highlight=dwl650 However, I have two DWL-650 cards and so far they have not been detected by Knoppix.

D-Link DWL-G650

This section detais how to get this card working with WPA-PSK enabled. All you need to do is follow three easy steps.

1. Configure wpa_supplicant by creating a configuration file. The configuration file should like something like this


The psk variable value is obtained by running the command:

  wpa_passphrase <ssid> <passphrase>

2. Next start wpa_supplicant by invoking the following command:

  wpa_supplicant -D madwifi -c wpa_supplicant.conf -i ath0 

By runnning this command you are able to authenticate with your wireless router.

3. After you have authenticated the final step is to obtain an IP address via DHCP. The command to use is:

  pump -i ath0

At this point you can type ifconfig to verify your IP address assignment.

Orinoco Gold

This was one of the first and best supported wireless 802.11b pcmcia cards under Linux. It is still one of the best cards for compatability, not just with Linux, but with several networking programs that work under Linux like NETstumbler and airsnort. Unfortunately, it tends to be very overpriced and can usually not be found at major retailers, but must be obtained mail order, if available at all.


Linksys WPC55AG

Here is a link to a forum discussion about this card: http://www.knoppix.net/forum/viewtopic.php?t=12351


Netgear WG111

Configuring the WG111 to use WPA-PSK on a wireless network

This card works very well in Knoppix 3.9 using ndiswrapper, but is as of yet untested in other versions of Knoppix (to my knowledge).

  • Commands:

Assuming that the drivers are on the cd in /dev/cdrom, then

mount /dev/cdrom/ /mnt/cdrom/

Find ndiswrapper configuration under Knoppix->Network/Internet and select netwg111.inf from /mnt/cdrom. After that finishes, create the configuration file that you will need shortly using the following command:

wpa_passphrase MySSIDHere MyPassphraseHere > /home/knoppix/wpa_supplicant.conf 

Now, use your favorite text editor (if you don't have one, try Kate under the menu item Editors) and edit the /home/knoppix/wpa_supplicant.conf you just created (see sample below).

With that completed, run the following command. Warning: As it is, the command will monopolize your current command window with potentially useful debugging output, including your encryption key; add -B if you would rather run it in the background (useful when you know it works already), remove -K to hide your key.

sudo wpa_supplicant -ddKt -i wlan0 -c /home/knoppix/wpa_supplicant.conf -Dndiswrapper

The following grabs an IP address if you use DHCP from your router.

sudo pump -i wlan0

And finally, tell Knoppix where to go to find the internet.

sudo route add default gw <Gateway/Router IP address here> 
  • wpa_supplicant.conf

Note: the bold lines were added in the editing steps for my Linksys WRT54G Router to accept the card. See the Useful Links at the end for a full explanation of all options that can be put in here.

psk=hex representation of the passphrase
  • Useful Links:

Wireless card success story (where I located the pump command)

Example wpa_supplicant.conf with full explanations and various configurations


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