413 lines
16 KiB
Plaintext
413 lines
16 KiB
Plaintext
********************** Linux-wlan-ng FAQ **************************
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For additions, corrections, and clarifications, send mail to
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solomon@linux-wlan.com with FAQ in the subject.
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*******************************************************************
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Q: What devices does the linux-wlan-ng driver support?
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Currently, the linux-wlan-ng driver supports the Intersil
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Prism2/2.5/3 chipsets. These chipsets are used in a wide
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variety of PCMCIA, PCI, and USB products. If it has a Prism
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chip in it, linux-wlan-ng should support it.
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Q: Will linux-wlan-ng support some feature or funkiness in
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the <pick one> Linux distribution?
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Our development target always consists of stock kernels from
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kernel.org and stock pcmcia_cs. If a given distribution
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chooses to do something funky, we rely on users of that
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distribution to contribute patches to deal with their
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funkiness.
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The quickest way to get some action on this kind of item is to
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communicate with any users of the same distribution that you
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can find on the linux-wlan-[devel|user] lists about working up
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a patch. If it's reasonably sane and doesn't break things for
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our development environment or for other distributions, we'll
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be more than happy to roll that patch into the next release.
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Q: What does "resultcode=implementation_failure" mean?
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Complicated Answer:
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Each command that can be issued with wlanctl-ng returns a status
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called "resultcode". Resultcode is something that we picked up
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from the 802.11 MLME definition. In the standard, resultcode
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is an enumeration with a fixed set of values. To be able to
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report failures that a driver detects that are outside the
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context of the 802.11 standard set of resultcode values, we
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invented the "implementation_failure" value.
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Simple Answer:
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Go look in your kernel log for more detailed error information.
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Q: I'm trying to use the HostAP/orinoco/aironet/wvlan driver and it
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won't work!
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That has nothing to do with the linux-wlan-ng driver. Go ask
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those responsible for those drivers.
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Q: Can I get Debian packages of linux-wlan-ng?
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A: Packages of linux-wlan-ng are available in the Debian unstable
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and testing trees now, and will eventually be shipped with a stable
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Debian release. The Debian packages include support for configuring
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linux-wlan-ng interfaces via /etc/network/interfaces, amoung other
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things. Complete details about the Debian-specific parts of these
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packages, including instructions for building a linux-wlan-ng modules
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package for your kernel can be found in the file
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/usr/share/doc/linux-wlang-ng/README.Debian.gz
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Q: Where do I find some RPMS for linux-wlan-ng? The ones on
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the ftp are dreadfully out of date!
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http://prism2.unixguru.raleigh.nc.us/
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(Maintained by Tim Miller)
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Q: I installed the RPMs/compiled the driver and installed it and it
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won't work when I try to run 'ifup wlan0' or whatnot.
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First, ensure you're running the most up-to-date version of
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the driver. Many problems have been fixed in newer releases.
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802.11 wireless networks are much more complex than wired
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ethernet networks. They require much more configuration than
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an ip address. If you are using pcmcia, edit the file
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/etc/pcmcia/wlan-ng.opts to set the network parameters. For
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PCI, PLX, or USB adapters, you need to edit /etc/wlan.conf.
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You also need to make sure you have the correct settings in
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/etc/modules.conf (alias wlan0 prism2_usb).
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Might we suggest you read the README file?
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Q: When I try to load the driver, I get a whole bunch of errors about
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unresolved symbols.
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The running kernel does not match the kernel the driver was
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compiled for. If you downloaded a RPM, make sure you
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downloaded the correct version for your kernel. This should not
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happen if you compiled the driver from source -- if it does, the
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kernel configuration you compiled against does not match the
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running kernel. Probably a screwed-up distro kernel.
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Q: I have a DWL-520 and it won't work!
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The DWL-520 claims to require a PCI 2.2 compliant motherboard.
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Only fairly new machines support this. Yes, the box lies. :)
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Check the documentation for your system and/or motherboard to see if
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it is PCI 2.2 compliant.
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NOTE: We have some reports of the DWL-520 working on PCI 2.1
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motherboards; your mileage may vary. See the following URL:
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http://www.personaltelco.net/index.cgi/DlinkDwl520
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NOTE: The Linksys WMP11 v2.7 is NOT prism-based, and
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thus not supported by this driver. The Actiontec PCI board is
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still known to be prism based; you may want to try that instead.
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Q: All I see is "Tx attempt prior to association, frame dropped"
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You are not associated with an access point. Double-check the
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settings in /etc/wlan.conf (USB, PCI, PLX) or /etc/pcmcia/wlan-ng.opts
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(for PCMCIA users). If all of these settings are correct (you
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did check with your admin, right?) make sure the access point
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doesn't have a MAC filter installed or has different WEP settings.
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If all of this is verified correct, and are using a PCMCIA
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card, try setting the "irq_mode=0" option. See the
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documentaiton in the pcmcia-cs sources.
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Q: I installed the modules, performed a 'wlanctl-ng wlan0 lnxreq_autojoin'
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command, and it still won't work!
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You did read the README, didn't you? You need to perform a
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"wlanctl-ng wlan0 lnxreq_ifstate ifstate=enable" in order to
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torn on the radio. The pcmcia scripts and the /etc/init.d/wlan
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script do this for you.
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Q: I have a XXX USB 802.11b device, will it work with this driver?
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Most 802.11b USB devices use the ATMEL AT76C503A chipset, which
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is not supported by the linux-wlan-ng project. However, there
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are some prism2.5-based USB adapters, most notably the Linksys
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WUSB v2.5. The other versions (1.0, 2.6, 3.0) are based on
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ATMEL chipsets. Another supported USB device is the Actiontec
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802UI3.
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Q: The wlan-ng driver says my ATMEL AT76C503A device is unsupported!
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Atmel has placed the source code of the Linux driver for the
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AT76C503A (and 501 or 502 - the PCMCIA variant) under the GPL
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in July 2002. The project can be found under
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http://www.sourceforge.net/projects/atmelwlandriver
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and it is in a rather usable state. The mailing list
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http://iprserv.jura.uni-leipzig.de/mailman/listinfo/atmel-wlan-usb
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still has many useful postings.
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Q: My prism2.5-based USB adapter won't work!
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An excellent guide can be found at:
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http://www.fuw.edu.pl/~pliszka/hints/prism2.html
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Q: My prism2.5-based USB adapter won't come up if it's plugged in at boot!
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Thanks to buggy firmware, it is often necessary to perform a
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device reset on initialization. You can perform this by adding
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"options prism2_usb prism2_doreset=1" in your /etc/modules.conf
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Intersil has released Primary firmware 1.1.2, which seems to
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have resolved this problem, at least on our test machines.
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Contact your vendor for a firmware update.
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To check the firmware version, run: "dmesg |grep ident"
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Q: My PC crashes when the USB device is plugged in!
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This is a result of the port reset necessitated by buggy firmware.
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You are probably using the 'usb-uhci' driver with an intel
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chipset. Unfortunately, the crashes happen deep within the USB
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core, so there's nothing the linux-wlan-ng driver can do.
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In the mean time, try using the 'uhci' host controller driver
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instead ("alias usb-controller uhci" in /etc/modules.conf), or
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plug the USB device into a hub.
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Linux kernel 2.4.19 is known to improve the situation somewhat,
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but the right way to fix it is to turn off the port reset
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(options prism2_usb prism2_doreset=0). The current firmware
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from Intersil alleviates the need to perform the reset.
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Q: My PC crashes when the USB device is unplugged!
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0.1.16-pre3 included some fixes that should eliminate the race
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condition that caused the oops-on-unload.
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Q: What's with these "Called from within soft interrupt context" messages?
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This is the result of a workaround to avoid a kernel oops in
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the USB driver code. You can ignore them.
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As of 0.1.15-pre5, a different workaround is in place.
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Q: Why doesn't promiscuous mode or monitor mode work under USB?
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Promiscuous mode works just fine, as of 0.1.15-pre5.
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Monitor mode also works, as of 0.1.14-pre6.
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Both modes are likely to be quite unreliable, especially under
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higher loads thanks to fundamental bandwidth limitations of the
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USB interface.
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Q: How come I can't transmit when in monitor mode?
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You can't. It's a fundamental "feature" of the hardware.
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Q: How come the /proc/net/wireless info isn't updated when in monitor mode?
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The definition of "signal quality" refers to the quality of the
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link to the associated access point. When you're in monitor
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mode, you're not associated, so this information is by defintion
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irrelevant.
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And regardless, the hardware doesn't update the registers we poll to
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obtain this information while in monitor mode.
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Q: What do the various monitor mode options do?
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enable=[true/false] Turn it on and off. required.
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channel=[1-14] Sniff channel. required.
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prismheader=[true/false] Optionally preppend a special
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radio header on the packet.
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Defaults to off.
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keepwepflags=[true/false] If you had WEP configured correctly
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the card will perform WEP decoding.
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Defaults to off.
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stripfcs=[true/false] When true, the 802.11 FCS is not
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stripped from incoming packets.
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Defaults off.
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truncate=[number] Truncates the captured frame.
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Q: How come iwconfig/iwspy/[random other wireless tool] doesn't work?
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linux-wlan-ng only supports a subset of the wireless
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extensions; generally read-only things. However, you won't
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need any of those tools as wlan-ng comes with its own set of
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tools that closely mirror the 802.11 spec. Have a look
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through the documentation and supplied scripts.
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That said, if more complete (ie read/write) wireless extension
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support is really important to you, you're more than welcome to
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implement it and submit a patch.
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As of 0.1.16-pre1, the wireless extension plumbing has been
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re-written, and further support is much easier now. And many
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more bits are hooked up now than before.
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Q: How do I know exactly what prism variant is on my card?
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When you load the driver, you see a line which reads like:
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ident: nic h/w id=0x8008 1.0.0
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1.0.0 is the hardware revision. Below is a (partial) list of IDs.
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0x8003, 0x8008 : Prism2 PCMCIA
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0x800b, 0x800c : Prism2.5 PCMCIA
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0x8012, 0x8013 : Prism2.5 PCI
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0x801a, 0x801b : Prism3 PCMCIA
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0x8021, 0x8022 : Prism3 PCI
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0x800f, 0x8010 : Prism2.5 USB (3863)
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0x801e, 0x801f : Prism2.5 USB (3861B)
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0x8025, 0x8026 : Prism3 USB
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Q: Where can I download updated firmware for my Prism2/2.5/3-based card?
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Ask your vendor. Due to legal reasons, we cannot
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provide updated frmware with the driver code.
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Q: How can I update my firmware under Linux?
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Use the 'prism2dl' utility. Note that it has been removed from
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newer revisions of the driver sources due to liability reasons --
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too many people fried their cards and blamed AVS for it.
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Q: Can I use my 802.11b card as an AP under Linux?
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Yes, and in the true free software fashion, there are several
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ways:
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a) linux-wlan-ng supports AP operation by using special tertiary
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firmware on prism devices. This firmware is not generally
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available, however. Contact Intersil for licensing terms.
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b) The Prism2 HostAP driver uses the special HostAP mode of the
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prism chipsets. http://people.ssh.com/jkm/Prism2/
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c) The OpenAP project, which involves flashing Linux on access
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points. http://opensource.instant802.com/
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Q: After a few minutes of use, my card stops responding! I'm using WEP.
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There seems to be card lockup problems with newer cards (new
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DWL-650 cards, linksys WPC11v3) when WEP is turned on. Since
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WEP is done in hardware, there is nothing the driver can do to
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resolve this. We suggest you pester your vendor for a firmware
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update.
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Prism2.5 boards are also known to lock up under heavy use; this
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is due to bugs in the WEP engine. Even if you perform a card
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reset, the WEP engine remains stuck.
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As an alternative, you can try out the host-based WEP present in
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0.1.15-pre1 and newer. It is still considered experimental,
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but the person typing this uses it on a daily basis.
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Intersil claims to have fixed this in firmware 1.4.0:
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"Fixed a hang condidion seen on certian hardware designs when
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using firmware WEP"
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Note there are other bugs in the firmware; as recently as 1.4.5
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Intersil included a fix that would "Correct an error that could
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cause the driver to no longer be able to communicate with the
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firmware"
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Contact your vendor and ask them to release updated firmware.
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Q: When using host-based WEP I get these strange intermittent connection
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lockups.
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This should be fixed in 0.1.15-pre3. If you are sill having
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problems, send a detailed message to the linux-wlan-devel
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mailing list.
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Q: When using the wlan-ng driver on a multiprocessor machine, I get
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packet corruption or random crashes/lockups.
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0.1.15-pre2 is the culmination of a major restructuring of
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internal driver locking.. Please give it (or newer) a shot
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if you're using a SMP system; we expect it to be much improved
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even on uniprocessor systems as we lock out system interrupts for
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far less time now.
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0.1.16-pre3 included a fix for a subtle SMP deadlock that was
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missed in 0.1.15-pre2 and earlier.
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0.1.16-pre4 included workarounds for PrismPCI hardware errata
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that would also manfest themselves as SMP problems, but could
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also affect uniprocessor machines in rare circumstanes.
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Q: I have a PCI adapter, and upon resuming from a suspend, the device is not
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responsive.
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Much like you need to run some commands to bring the card to life
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when the PC is first booted, you also need to perform similar
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steps when the card comes out of suspend. Run '/etc/init.d/wlan start'
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and all should be well.
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You'll need to be running 0.1.15-pre3 or newer for this to work
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properly.
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The prism2.5/3 chipsets do not support PCI power management, so
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this is the best we can realistically do.
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Q: I have a Linksys WMP11, and under moderate to heavy traffic, I get
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errors like "unknown port number" and "invalid frame type"
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Make sure you're using the latest firmware avaliable from
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Linksys's web site. According to the firmware release notes:
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"Changes were made to prevent erroneous data from being
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transferred over the PCI bus"
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Note that this problem has also beeen confirmed on the D-Link
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DWL-520. You will need firmware 1.3.5 or newer to resolve this.
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Q: I have a D-Link DWL-650/650+/520+ card, why doesn't it work with
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this driver?
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The DWL-650 comes in three flavors; older ones have grey
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antennae, with no revision number on the back.
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Second-generation has a black antenna and the back reads
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"H/W J3 F/W 1.x.x". Both of these will work. The third-
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generation, with a grey antenna, has "H/W A1, F/W x.x", and
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will NOT work; It has the same hardware as the "plus" series
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of cards.
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The "plus" series of cards from D-Link use the Texas Instruments
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ACX100/TNETW1100 chipset. TI has not been forthcoming with
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programming information. Politely ask TI and D-Link for Linux
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drivers and/or docs.
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We've been told that TI will be releasing binary-only Linux
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drivers sometime in December. In the mean time, return the
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card and buy one that works with Linux.
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Q: I have a Linksys WMP11 v2.7 card; why doesn't it work with this driver?
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Linksys, in their grand tradition, likes to introduce completely
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new cards but re-use the model number. The WMP11 v2.7 utilizes the
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Broadcomm chipset, and is not supported by linux-wlan-ng. Politely
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ask Linksys and/or Broadcomm for Linux drivers and/or docs.
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Q: What other resources are there for Wireless LANs under Linux?
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http://www.fuw.edu.pl/~pliszka/hints/wireless.html
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http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Linux.Wireless.drivers.html
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