[CentOS] Wifi not working

Wed Jul 28 17:49:29 UTC 2010
Dave Miller <dave at davenjudy.org>

Larry Vaden <vaden at ...> writes:

> On Tue, Jul 27, 2010 at 6:33 PM, Phil Savoie <psavoie1783 <at> 
rogers.com> wrote:
> > Beginning DHCP transaction.
> > Jul 27 19:32:23 smurf3 NetworkManager: <info>  Device 'wlan0' DHCP
> > transaction took too long (>45s), stopping it.
> > Jul 27 19:32:23 smurf3 NetworkManager: <info>  wlan0: canceled DHCP
> > transaction, dhcp client pid 30770
> It would seem that one possibility is that the AP is not running a
> DHCP server.
> Another is that if the AP is running a DHCP server, it is restricting
> IP addresses to known clients.
> kind regards/ldv
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A couple of suggestions:

1) I had very similar problems with some of the Broadcom drivers for my 
laptop ("transaction took too long").  An easy test is to *BRIEFLY* disable 
security on the AP and see if your system connects.  If the two systems 
connect then there is a problem syncing with WPA security.  A possible 
alternative is to use ndiswrapper and the Windows driver instead of the 
native Linux driver.  I've been really happy with ndiswrapper even if it
means I'm "impure" for using a Windows driver.

2) The actual key exchange is handled by a daemon called wpa_supplicant.  
It can be finicky.  The config files are /etc/sysconfig/wpa_supplicant 
and /etc/wpa_supplicant/wpa_supplicant.cnf  You may have better luck 
fiddling with some of the settings in the configuration files.  As an 
example, ndiswrapper works better for me with -D wext instead of -D 

I've also seen restating wpa_supplicant (as root, "service wpa_supplicant
restart) fix things.  Also, I've had better luck just getting the 
wpa_supplicant configuration right and not using NetworkManager (service 
NetworkManager stop).  I just do a "ifup wlan0" from the command line.