Issue: iwlist scanning sees the network; dhclient can't connect

Issue: iwlist scanning sees the network; dhclient can't connect

[Thiago F. Tavares]

 
Hello,
 
I have a problem with the broadcom wireless card (BCM4306 using b43).
I'm can list the wireless ESSIDs with "iwlist scanning" command, but I'm
can't connect in the LAN. My dhclient or dhcpcd can't receive an IP.
When I set a static IP, I can't ping the gateway.
 
Follows the output of the interesting commands:
 


#ifconfig
 
eth0      Link encap:Ethernet  HWaddr #######################  
          inet addr:192.168.0.200  Bcast:192.168.0.255
Mask:255.255.255.0
          inet6 addr: ##################### Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:953 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1055 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:750261 (732.6 KiB)  TX bytes:178857 (174.6 KiB)
          Interrupt:220 Base address:0xe000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:24 errors:0 dropped:0 overruns:0 frame:0
          TX packets:24 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1648 (1.6 KiB)  TX bytes:1648 (1.6 KiB)

wlan0     Link encap:Ethernet  HWaddr ###################
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:11 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:3941 (3.8 KiB)  TX bytes:2004 (1.9 KiB)

wmaster0  Link encap:UNSPEC  HWaddr ################
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
 

-------------------------------------------------------------------
#iwlist scanning


lo        Interface doesn't support scanning.

eth0      Interface doesn't support scanning.

wmaster0  Interface doesn't support scanning.

wlan0     Scan completed :
          Cell 01 - Address: ##:##:##:##:##:##
                    ESSID:"fastermangrate-on-song"
                    Mode:Master
                    Channel:11
                    Frequency:2.462 GHz (Channel 11)
                    Quality=76/100  Signal level=-58 dBm  Noise
level=-127 dBm
                    Encryption key:off
                    Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 18 Mb/s
                              24 Mb/s; 36 Mb/s; 54 Mb/s; 6 Mb/s; 9 Mb/s
                              12 Mb/s; 48 Mb/s
                    Extra:tsf=00000051a4c1557d
 
------------------------------------------------------------------- 
#dhclient wlan0


There is already a pid file /var/run/dhclient.pid with pid 3239
killed old client process, removed PID file
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

wmaster0: unknown hardware address type 801
wmaster0: unknown hardware address type 801
Listening on LPF/wlan0/##:##:##:##:##:##
Sending on   LPF/wlan0/##:##:##:##:##:##
Sending on   Socket/fallback
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 5
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 7
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 12
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 12
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 16
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 9
No DHCPOFFERS received.
No working leases in persistent database - sleeping.
 

--------------------------------------------------------------------


Please, help me with this problem.
 
Thank you.
 
 
Best Regards,
 
 

    Thiago Tavares

(CCNA - CISS - LPIC1)

Re: Issue: iwlist scanning sees the network; dhclient can't connect

[Pavel Roskin]

On Wed, 2008-07-30 at 16:13 -0300, Thiago F. Tavares wrote:
> Hello,
>  
> I have a problem with the broadcom wireless card (BCM4306 using b43).
> I'm can list the wireless ESSIDs with "iwlist scanning" command, but I'm
> can't connect in the LAN. My dhclient or dhcpcd can't receive an IP.
> When I set a static IP, I can't ping the gateway.

dhclient is not suitable for wireless networking because it brings the
interface down briefly and breaks the connection.  So I suggest that you
use static addresses or a DHCP client that doesn't bring the interface
down.

Please check iwconfig output.  In particular, please see "access point"
and "link quality".  If the later is 0, there is no association.  If
there is no association, no IP packets can go through.  Try
reestablishing the association by setting ESSID with iwconfig while the
interface is up.

Also please see the kernel log for possible signs of trouble.  It's
shown by the "dmesg" command.

-- 
Regards,
Pavel Roskin

Re: Issue: iwlist scanning sees the network; dhclient can't connect

[Michael Buesch]

On Wednesday 30 July 2008 21:36:42 Pavel Roskin wrote:
> On Wed, 2008-07-30 at 16:13 -0300, Thiago F. Tavares wrote:
> > Hello,
> >  
> > I have a problem with the broadcom wireless card (BCM4306 using b43).
> > I'm can list the wireless ESSIDs with "iwlist scanning" command, but I'm
> > can't connect in the LAN. My dhclient or dhcpcd can't receive an IP.
> > When I set a static IP, I can't ping the gateway.
> 
> dhclient is not suitable for wireless networking because it brings the
> interface down briefly and breaks the connection.  So I suggest that you
> use static addresses or a DHCP client that doesn't bring the interface
> down.

dhclient works fine for me. Although it's true that it sometimes
messes with up/down state. But you _can_ use it, if you take some care.

I suggest that you first associate with the wireless network before trying
to get an IP. That might result in slightly better connection qualities
to your AP.

Read the manpage for iwconfig and friends.

-- 
Greetings Michael.

Re: Issue: iwlist scanning sees the network; dhclient can't connect

[Pavel Roskin]

On Wed, 2008-07-30 at 21:41 +0200, Michael Buesch wrote:

> dhclient works fine for me. Although it's true that it sometimes
> messes with up/down state. But you _can_ use it, if you take some care.

True.  But b43 has the lowest dhclient survival rate of all drivers I
know.  That's an empirical observation, of course.

-- 
Regards,
Pavel Roskin

Re: Issue: iwlist scanning sees the network; dhclient can't connect

[Johannes Berg]

On Wed, 2008-07-30 at 15:51 -0400, Pavel Roskin wrote:
> On Wed, 2008-07-30 at 21:41 +0200, Michael Buesch wrote:
> 
> > dhclient works fine for me. Although it's true that it sometimes
> > messes with up/down state. But you _can_ use it, if you take some care.
> 
> True.  But b43 has the lowest dhclient survival rate of all drivers I
> know.  That's an empirical observation, of course.

I think debian patches out the down/up behaviour. We may be seeing that.

johannes

Re: Issue: iwlist scanning sees the network; dhclient can't connect

[Michael Buesch]

On Thursday 31 July 2008 10:41:05 Johannes Berg wrote:
> On Wed, 2008-07-30 at 15:51 -0400, Pavel Roskin wrote:
> > On Wed, 2008-07-30 at 21:41 +0200, Michael Buesch wrote:
> > 
> > > dhclient works fine for me. Although it's true that it sometimes
> > > messes with up/down state. But you _can_ use it, if you take some care.
> > 
> > True.  But b43 has the lowest dhclient survival rate of all drivers I
> > know.  That's an empirical observation, of course.
> 
> I think debian patches out the down/up behaviour. We may be seeing that.

Oh, that might explain why I don't see this behaviour.


-- 
Greetings Michael.

Re: Issue: iwlist scanning sees the network; dhclient can't connect

[Dan Williams]

On Thu, 2008-07-31 at 15:31 +0200, Michael Buesch wrote:
> On Thursday 31 July 2008 10:41:05 Johannes Berg wrote:
> > On Wed, 2008-07-30 at 15:51 -0400, Pavel Roskin wrote:
> > > On Wed, 2008-07-30 at 21:41 +0200, Michael Buesch wrote:
> > > 
> > > > dhclient works fine for me. Although it's true that it sometimes
> > > > messes with up/down state. But you _can_ use it, if you take some care.
> > > 
> > > True.  But b43 has the lowest dhclient survival rate of all drivers I
> > > know.  That's an empirical observation, of course.
> > 
> > I think debian patches out the down/up behaviour. We may be seeing that.
> 
> Oh, that might explain why I don't see this behaviour.

We all agreed at the OLS Wireless Summit that the up/down behavior of
dhclient was just f**king stupid and should be patched out.  Upstream
doesn't seem to be very responsive.

It just kills mac80211-based drivers, and drivers that do firmware
upload on dev->open() because all settings get lost and the driver would
have to re-load everything, which is ton of code in the driver that
shouldn't have to be there.  It's bad for Intel WiMAX devices too
because they do firmware upload in dev->open().

Dan

Re: Issue: iwlist scanning sees the network; dhclient can't connect

[Pavel Roskin]

On Thu, 2008-07-31 at 09:49 -0400, Dan Williams wrote:
> We all agreed at the OLS Wireless Summit that the up/down behavior of
> dhclient was just f**king stupid and should be patched out.  Upstream
> doesn't seem to be very responsive.

Sorry for going offtopic, but somebody picked up dhcpcd, and it's in a
pretty good shape now, preparing for 4.0 release.  It supports dhclient
scripts, works with NetworkManager, and doesn't bring the interface
down.  It even have a git repository, with the latest commit 79 made
minutes ago.

-- 
Regards,
Pavel Roskin

Re: Issue: iwlist scanning sees the network; dhclient can't connect

[Dan Williams]

On Thu, 2008-07-31 at 11:01 -0400, Pavel Roskin wrote:
> On Thu, 2008-07-31 at 09:49 -0400, Dan Williams wrote:
> > We all agreed at the OLS Wireless Summit that the up/down behavior of
> > dhclient was just f**king stupid and should be patched out.  Upstream
> > doesn't seem to be very responsive.
> 
> Sorry for going offtopic, but somebody picked up dhcpcd, and it's in a
> pretty good shape now, preparing for 4.0 release.  It supports dhclient
> scripts, works with NetworkManager, and doesn't bring the interface
> down.  It even have a git repository, with the latest commit 79 made
> minutes ago.

Yeah, I'm aware of that.  But at the same time, there's a lot of
procedure, knowledge, integration, and custom scripts built up around
dhclient that isn't going to change overnight.

Dan