'/sbin/dhclient wlan0' does not work in centos 5.3 (kde3)

[saivin]

Hi all,
I'm trying to configure wireless on my laptop (iwl3945 and centos 5.3). I've installed iwl3945-firmware and loaded the module also. But I'm not able to get IP address from DHCP.

When I do /sbin/dhclient wlan0 I get the following error:

[saivin@sv-centos ~]$ sudo /sbin/dhclient wlan0
Password:
Internet Systems Consortium DHCP Client V3.0.5-RedHat
Copyright 2004-2006 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/wlan0/00:1c:bf:c8:f2:1b
Sending on   LPF/wlan0/00:1c:bf:c8:f2:1b
Sending on   Socket/fallback
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 8
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 18
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 16
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 19
No DHCPOFFERS received.
No working leases in persistent database - sleeping.

However, dhclient works fine for eth0. What could be the problem and how to go about it?

[saivin]

Hmm...before somebody asks, the iwconfig states it is associated with my AP and iwlist scans my AP fine.

[root@sv-centos saivin]# /sbin/iwconfig wlan0
Warning: Driver for device wlan0 recommend version 21 of Wireless Extension,
but has been compiled with version 20, therefore some driver features
may not be available...

wlan0     IEEE 802.11  ESSID:"SV"
          Mode:Managed  Frequency:2.412 GHz  Access Point: Not-Associated
          Tx-Power=15 dBm
          Retry min limit:7   RTS thr:off   Fragment thr=2352 B
          Encryption key:off
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

[root@sv-centos saivin]# /sbin/iwlist wlan0 scan
Warning: Driver for device wlan0 recommend version 21 of Wireless Extension,
but has been compiled with version 20, therefore some driver features
may not be available...

wlan0     Scan completed :
          Cell 01 - Address: 00:1B:57:FD:4D:19
                    ESSID:"SV"
                    Mode:Master
                    Channel:11
                    Frequency:2.462 GHz (Channel 11)
                    Quality=93/100  Signal level=-36 dBm  Noise level=-127 dBm
                    Encryption key:on
                    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=00000000190c8185

As you can see it is giving some warning. But I'm not able to makeout what it means. Is my problem related to this warning?

[dehuatan]

There are some issues related with network-script against the WIFI card. We need walk around.
Here is the description about using WEP encryption.

1> It is supposed that related drivers are installed.
run command "lspci | grep 4965" can see the hardware.
run command "lsmod | grep 80211" can see the loaded modules.
or the NetworkManager worked for you.

2> disable NetworkManager service by commands
chkconfig NetworkManager off
service NetworkManager stop

3> cp /etc/sysconfig/network-scripts/ifcfg-wmaster0 into /etc/sysconfig/network-scripts/ifcfg-wlan0

4> change line "TYPE=Ethernet" into "TYPE=Wireless" against file /etc/sysconfig/network-scripts/ifcfg-wlan0 and save it.

5> from the task bar by selection System->Administration->Network orderly,
chosing item wlan0 as Device,
focusing Devices tab, clicking Edit button,

In General tab
mark "Activate device when computer starts",
chosing radio button "Automatically obtain IP address settings with dhcp"
mark "Automatically obtain DNS information from provider"

In Wireless Setings tab
Mode->Managed
Namework name(SSID)=>Specified into YOUR_SSID_FROM_YOUR_AP
Authentication=>Open system (open) [my case]
Key (use 0x for hex)=>0x[your AP SSID key], (NOT passphase)

Click OK, click Save from menu item File.

6> modifile /etc/sysconfig/network-scripts/ifup-eth
6.1> add line
/bin/rm -fr /var/lib/dhclient/dhclient-${DEVICE}.leases
before line
DHCLIENTARGS="${DHCLIENTARGS} ${ONESHOT} -q ${DHCLIENTCONF} -lf /var/lib/dhclient/dhclient-${DEVICE}.leases -pf /var/run/dhclient-${DEVICE}.pid"

6.2> add 2 lines
/bin/rm -fr /var/lib/dhclient/dhclient-${DEVICE}.leases
/bin/rm -fr /var/run/dhclient-${DEVICE}.pid
before line
# end dynamic device configuration
in the "else" section for line
if /sbin/dhclient ${DHCLIENTARGS} ${DEVICE} ; then

there will be like
if /sbin/dhclient ${DHCLIENTARGS} ${DEVICE} ; then
echo -n $" done."
else
/bin/rm -fr /var/lib/dhclient/dhclient-${DEVICE}.leases
/bin/rm -fr /var/run/dhclient-${DEVICE}.pid
echo -n $" failed."
exit 1
fi
# end dynamic device configuration

7> modify file /etc/sysconfig/network-scripts/ifup
go to bottom of the file, change line
exec ${OTHERSCRIPT} ${CONFIG} $2
into following lines

# exec ${OTHERSCRIPT} ${CONFIG} $2
times_tried=0
while (true); do
if ${OTHERSCRIPT} ${CONFIG} $2 ; then
exit 0
else
times_tried=$((times_tried + 1))
if ((times_tried > 1)); then
exit 1
fi
fi
done

Pay attentation: command exec in shell will call execel interface in C language.
No exit after command exec executed.

8> remarks

8.1> comment for 6>
dhclient command will hang up if its the pid file exists.

8.2> comment for 7>
boot Wireless always failed at the first time, need try one time at system booting up.
It may be caused by script ifup-wirelss that I dont the inside.

After those modification, my CentOS 5.4 on HP DV9500T notebook(Intel 4965 Wireless) can start wirelles conection at boot time.

Good luck.