Troubleshooting wireless configuration/setup

[Christoph Georgi]

Hi,

a lot of people seem to have some problems with setting up their 
wireless.. As Ubuntu's Wiki already supplies Howtos for setting up 
wireless, I just want to add a small howto troubleshooting those 
networks. (Maybe someone can parse it into the wiki.. I have not yet 
bothered learning that. TIA)

1. Check whether the card (as a piece of hardware) can be seen: Type '$ 
lspci' and check whether your wifi card is present or not.

2. (esp. for notebooks) Look at the output of the messages ('$ tail -f 
/var/log/messages') as you insert the PCMCIA card. Something should 
happen. You should be able to see that the drivers are loaded or a 
statement that the driver is already loaded.

3. Wireless extension: Type '$ iwconfig' and have a look whether there 
is a wireless extension available on any network adapter; there should 
be at least one if you have inserted a wireless card.

4. Bring up your wireless interface ('$ sudo ifup <interface>') and see 
what happens. (For help on the mailing list, please post that output!)

If so far everything works, the card should send DHCP Requests to the 
broadcast IP. If you have not got so far, you're most likely to have a 
problem with your wireless card driver! And that's a problem by its own ;)


5. Have a look again at the output of '$ iwconfig'. The MAC address of 
the Access Point be stated there in the first (?) line --> The card is 
able to "see" the AP. (For help on the mailing list, please post the 
output.)

6. WHAT MOST PEOPLE FORGET: Check whether the AP can "see" you! Log into 
your AP and check the logfiles. The MAC of your wireless card should 
appear there somewhere.

6.1 If this is not the case then you most likely have mismatching 
wireless settings: Check '$ iwconfig' for "Rx invalid nwid" (wrong 
ESSID), "Rx invalid crypt" (mismatching authentification method/key), 
"Rx invalid frag" (I haven't got a clue). Usually they show up all 
together, which should tell you to check your config!: Have a look at 
/etc/network/interfaces (post the output for further inquiries) and 
compare the settings to the configuration of your AP.

In case the settings don't match, change the interfaces file and change 
the setting with the according iwconfig command (see '$ man iwconfig')

6.2 If your settings match, try another wireless card?! Sorry, I can't 
help you :-/

7. If your card sees the AP and the AP sees you, you are likely to have 
skrewed up something within your network, as this state compares to a 
pluged-in wire where both interfaces (and the wire) work perfectly fine.

7.1 If you don't get an IP check your DHCP Server settings 
(/etc/dhcp3/dhcpd.conf)

7.2 If you have an IP try pinging your Server to see whether the 
connection is OK

7.3 If you can ping the server there must be a problem with your service 
settings. But that has nothing to do anymore with your wireless (so I 
can finally stop here) ;)


I hope that helps one or the other and might save me some time telling 
people to check the Client MAC on the AP and to post the output of $ 
iwconfig ;)

regards
.christoph




davegod75 wrote:
> Jack Hudson Wrote: 
> 
>>On Mon, 2005-02-14 at 13:42 -0600, Luis Murillo wrote:
>>
>>>ok, but are there any 802. 11B cards, because you only mention the g
>>
>>cards and I think that would be too overkill for me at the moment and
>>would prefer to buy a b only card. Though I know that g cards can
>>connect to B networks.
>>
>>>Thanks. 
>>>
>>>   >Many thanks for that.
>>>   >I found this site as a result.
>>>   >http://prism54.org/supported_cards.php
>>>
>>>lmurillo
>>>
>>
>>>Hi I have been using Linksys WUSB12 v1 adapter on different computers
>>
>>running Warty 4.10 and the linux.wlan drivers and it installs
>>
>>> without any problems. Once you get your config (Wlancfg) set up it
>>
>>works like a champ.
>>At home I use a WRT54g linksys Router for both my wired and wireless
>>connects. I run Ubuntu on a P4 3.2 mhx with the wireless adapter and a
>>Balance laptop with Ubuntu which shows to have a prism3_usb adapter
>>internally and I have it configured with wlan also and it works great.
>>Hope this helps.
>>Jack Hudson
>>Registered linux user #365587
>>
>>---
>>[This E-mail scanned for viruses by Declude Virus]
>>
>>
>>-- 
>>ubuntu-users mailing list
>>ubuntu-users at lists.ubuntu.com
>>http://lists.ubuntu.com/mailman/listinfo/ubuntu-users
> 
> how do you setup the wlan to get it to work?
> 
> 

-- 


Christoph Georgi
-----------------------------
email.  christoph.georgi at web.de
fon.	+64 (0)9 815 8259

registered linux user #380268
ubuntulinux 4.10 (warty)