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Re: dhcp client wifi setup



On Sunday, 25 December 2005 at  1:12:53 +0100, Florian Kulzer wrote:
> Hi Richard,
> 
> Richard Lyons wrote:
> >But ifup eth0 gives
> >
> >    etho: New link status: Connected (0001)
> >    Listening on LPF/eth0/00:02:2d:a6:07:bb
> >    Sending on   LPF/eth0/00:02:2d:a6:07:bb
> >    DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8
> >    ...more similar...
> >    No DHCPOFFERS received.
> >    No working leases in persistent database.
> >
> >    Exiting.
> >
> >    Failed to bring up eth0.
> 
> Maybe you can first try to find out if you have a problem with the
> interface itself or with the dhcp-client. To configure the interface
> directly you can use the iwconfig command (as root)

I did say that it connects perfectly when the router is not requiring
WEP security.  So the hardware is functioning normally.

> 
> iwconfig eth0 essid xxxxxxxx
> iwconfig eth0 key xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xx

Yes, this is how I test it.  If I follow uo with 'ifup eth0', as quoted
above, I get no DHCP offer.  If I turn off the WEP at the router and
comment out the corresponding lines in /etc/network/interfaces (the
lines with wireless-essid and wireless-key), then it immediately
connects and functions normally.
> 
> After you have done this the output of "iwconfig eth0" will tell you if
> the interface works and if it has associated with the correct access
> point. The output of "iwlist eth0 scan" might also be helpful, as it
> shows all detected access points and signal levels.
> 
before giving the two iwconfig commands you list above, iwconfig eth0 gives

eth0      IEEE 802.11b  ESSID:""   Nickname "HERMES I"
          Mode:Managed  Frequency:2.422 GHz  Access Point: Not-Associated
          Bit Rate:11 Mb/s  Sensitivity:1/3
          Retry limit:4   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=0/92  Signal level=134/153  Noise level=134/153
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

and after them:

eth0      IEEE 802.11b  ESSID:"Coixxxxxxxxx"   Nickname "HERMES I"
          Mode:Managed  Frequency:2.422 GHz  Access Point: Not-Associated
          Bit Rate:11 Mb/s  Sensitivity:1/3
          Retry limit:4   RTS thr:off   Fragment thr:off
          Encryption key:xxxx-xxxx-xxxx-xxxx-xxxx-xxxx-xx   Security mode:open
          Power Management:off
          Link Quality=0/92  Signal level=134/153  Noise level=134/153
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

castagna:~# iwlist eth0 scan
eth0      Interface doesn't support scanning : Network is down

I tried adding
castagna:~# iwconfig eth0 mode Ad-Hoc
castagna:~# ifup eth0 

...gives the same unsuccessful connection attempt as in my previous post 
quoted above, but now

castagna:~# iwlist eth0 scan
eth0      Scan completed :
          Cell 01 - Address 00:0F:BF:51:D7:FC
                    ESSID:"Coixxxxxxx"
                    Mode:Master
                    Frequency:2.427 GHz (Channel 4)
                    Signal level:-68 dBm  Noise level:-93dBm
                    Encryption key:on
          Cell 02 - Address...........
                    ...etc. for three cells in all

But I still cannot connect.  I noticed the mode sent by the router is "Master", 
so I tried changing mode back to Managed: same result.

> If the interface fails to associate even though the signal level is
> sufficient you might be missing the relevant modules to handle the
> cryptography which is necessary for WEP. Unfortunately I do not know
> anything about the specifics of the orinoco driver, but I know that for
> example the Intel wireless drivers need an extra module for the
> ieee80211 crypto. Newer kernels have the option CONFIG_IEEE80211 for
> this. Maybe the documentation of your driver can help you further.

Kernel is 2.6.14-2-686 -- surely new enough?
> 
> On the other hand, if the interface does associate with the AP you know
> that the problem is caused by the dhcp-client. Run "dhclient eth0" and

That gives exactly the same result as ifup eth0.

> see if it still fails. I am currently using Sid's dhcp-client package
> version 2.0pl5-19.4 

So am I.

> and it works without problems. Check your
> /etc/dhclient.conf for settings which could cause trouble, for example

Maybe this is the problem: it has only two uncommented lines:

supersede domain-name "co-ho.net"
prepend domain-name-servers 192.168.0.3

both needed for correct functioning of DNS (and the same as all other 
Linux boxes on the network). Windows and Mac boxes manage without: I do 
not understand where they get their internal DNS from, but that is a 
separate issue of no urgency whatsoever.


> an unusually short timeout.

The DHCPDISCOVER seems to select random lengths of time between 5 and 20
seconds, and to repeat five times for each 'ifup' or 'dhclient'.  I suppose 
this is default behaviour.  Since each run includes at least two longer 
examples (>15s), I don't suppose altering this would improve things. And
I still suspect I have something else actually misconfigured.

> 
> I hope this helps.

Thanks for all the input, but regrettably is hasn't yet...

-- 
richard



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