Wireless network setup

Bryce wrote:
> Neil Jones wrote:
>
>> I have downloaded the latest Knoppix and Fedora Live CDs. The only
>> network device that is active is eth0 with no IP address. Now, is this
>> wired Ethernet port or the Wireless port? When I was reading up on
>> configuring the Wireless card on Knoppix, there is a very liberal
>> interchange between the device names eth0 and wlan0, in the network
>> commands. On Knoppix, I have tried the commands that were listed for
>> the "net" prefix, starting with the obvious ones first. I have also
>> tried the iwconfig command to assign the IP address for wlan0. None of
>> these commands worked for me.
>>
>> Are there any kernel options that will start up the wlan0 interface? My
>> DSL router uses the SSID and WPA keys, therefore it needs to
>> authenticate with the router before it can get a DHCP address.
>
> Bad timing: all of the mind-readers are away at the annual Karnak
> Conference. Only us chickens are here to guess at what's up.
>
> Disable encryption on your router. Connect an ethernet cable between your
> computer and router. eth0 is probably your wired nic. Does /sbin/ifconfig
> show an IP address for eth0 now?

Agreed. eth0 is probably the wired NIC.

> To get that unnamed wireless card recognised, you may need to load its
> driver with modprobe.

You probably need to start with the wireless firmware (microcode),
assuming it's publicly available. The output of

lspci | grep -i net

will probably provide more info for people to be able to help you.

On Sat, 22 Aug 2009 16:59:24 +0200, Neil Jones wrote:

> I have downloaded the latest Knoppix and Fedora Live CDs. The only
> network device that is active is eth0 with no IP address. Now, is this
> wired Ethernet port or the Wireless port? When I was reading up on
> configuring the Wireless card on Knoppix, there is a very liberal
> interchange between the device names eth0 and wlan0, in the network
> commands. On Knoppix, I have tried the commands that were listed for
> the "net" prefix, starting with the obvious ones first. I have also
> tried the iwconfig command to assign the IP address for wlan0. None of
> these commands worked for me.
>
> Are there any kernel options that will start up the wlan0 interface? My
> DSL router uses the SSID and WPA keys, therefore it needs to
> authenticate with the router before it can get a DHCP address.
>
> Thank you in advance for any help.
>
> NJ


ifconfig

Neil Jones wrote:

> On Knoppix, I have tried the commands that were listed for
> the "net" prefix, starting with the obvious ones first. I have
> also tried the iwconfig command to assign the IP address for
> wlan0. None of these commands worked for me.

iwconfig is for setting wireless parameters of the link level,
not the IP address.

> Are there any kernel options that will start up the wlan0
> interface?

No. It's all configured in userspace.

> My DSL router uses the SSID and WPA keys, therefore
> it needs to authenticate with the router before it can get a
> DHCP address.

To use WPA you need wpa_supplicant. It comes with all major Linux
distributions.

Here's a quick guide, for how to do it completely manually:

Linux doesn't mandate a specific naming convention for network
interfaces, driver writers can choose anything they want. So
first find out which your wireless interfaces are, by simply
typing iwconfig on a root shell.

On my laptop (narfi) this gives:

iwconfig
lo no wireless extensions.

sit0 no wireless extensions.

eth0 no wireless extensions.

wmaster0 no wireless extensions.

wlan0 IEEE 802.11abgn ESSID:""
Mode:Managed Frequency:2.437 GHz Access Point: Not-Associated
Tx-Power=15 dBm
Retry min limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management: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

pan0 no wireless extensions.

Not surprising the interface "wlan0" is a wireless interface.

If there's no interface showing up with wireless extensions, then you
* don't have the driver loaded
or
* your installtion misses the firmware files
or
* your wireless hardware is not (yet) supported by Linux

If you were about to connect to a public, unprotected access point,
you would use iwconfig to setup the interface e.g.:

iwconfig wlan0 ssid "HotSpot" enc off

To use WPA you must configure your wpa_supplicant. You can either do
this by using its GUI "wpa_gui" - this is quite self explanatory, I
don't think I've to explain that one, wpa_supplicant must be started
before starting wpa_gui though.

Or you're creating the file /etc/wpa_supplicant/wpa_supplicant.conf
by hand. Use this template:

--- BEGIN /etc/wpa_supplicant/wpa_supplicant.conf ---

ctrl_interface=/var/run/wpa_supplicant
ctrl_interface_group=0

network={
ssid="..." # your SSID
proto=WPA2 WPA
key_mgmt=WPA-PSK
pairwise=CCMP TKIP
group=CCMP TKIP
psk="..." # put your WPA password here
}

--- END ---

You can then start wpa_supplicant on the wireless interface:

/sbin/wpa_supplicant -Dwext -c/etc/wpa_supplicant/wpa_supplicant.conf -B -iwlan0 -P/var/run/wpa_supplicant-wlan0.pid

wpa_supplicant will background. To see what's going on start wpa_cli.

Once the connection is made you can configure the address of your interface.
In case of DHCP it's easy as, depending on which of dhcpcd or dhclient are
installed.

dhcpcd wlan0

or

dhclient wlan0

For static IP configuration use

ip addr add $ADDRESS/$NETBITS dev wlan0
ip route add default via $ROUTER dev wlan0
rm /etc/resolv.conf.new
for NS in $NAMESERVERS ; do echo "nameserver $NS" >> /etc/resolv.conf.new ; done
mv /etc/resolv.conf.new /etc/resolv.conf

e.g.

ip addr add 192.168.1.123/24 dev wlan0
ip route add default via 192.168.1.254 dev wlan0
rm /etc/resolv.conf.new
for NS in 192.168.1.253 192.168.1.252 ; do echo "nameserver $NS" >> /etc/resolv.conf.new ; done
mv /etc/resolv.conf.new /etc/resolv.conf

Of course all major distributions provide you with a convenient
configuration interface abstracting away all those gory details,
however this is specific to each distribution.
Just RTFM of the distribution you use.


Wolfgang

Wolfgang Draxinger wrote:
> Neil Jones wrote:
>
>> On Knoppix, I have tried the commands that were listed for
>> the "net" prefix, starting with the obvious ones first. I have
>> also tried the iwconfig command to assign the IP address for
>> wlan0. None of these commands worked for me.
>
> iwconfig is for setting wireless parameters of the link level,
> not the IP address.
>
>> Are there any kernel options that will start up the wlan0
>> interface?
>
> No. It's all configured in userspace.

Odd. Mine is configured at boot.

Cant remember how I did it tho.

The Natural Philosopher wrote:

>> No. It's all configured in userspace.
>
> Odd. Mine is configured at boot.

.... by the init system, which runs in userspace.

The term "booting" has nothing to do with the distinction "kernelspace"
vs. "userspace". Booting is a special state a system can be in, namely when
a system is newly started and initializes all its subsystems.


Wolfgang