How to configure your Network Card

Network Interfaces 

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So you have Backtrack running installed on a HDD, you can now configure your cards to use the network. You can also do this exactly the same if you are running the distro from the CD, but your settings will not be saved as the CD is a read only medium. There are plenty of different ways to configure these wired cards and plenty of tools to do it. What I am showing here is the generic Linux commands which should be the same for other distro's.
To turn on your ethernet network card (LAN):
ifconfig eth0 up
The eth0 is the name of the card, this could change depending on what hardware you have installed. To get a list of all adapters: ifconfig -a
This will list all (-a) interfaces.
To get DHCP to assign a network address automatically from the DHCP server:
dhcpcd eth0
This will run it only on eth0, if you omitted the interface you would run the DHCP discovery process on all compatible cards.

Then check if you have an address:
ifconfig eth0
You should see an IP address in there somewhere.

If you want a static IP address instead of a dynamic one:
ifconfig eth0 192.168.1.2
Or whatever IP you want! If you want a variable subnet mask (beyond the scope of this thread!):
ifconfig eth0 192.168.1.2 netmask 255.255.255.224

To manually add a default gateway:
route add default gw 192.168.1.1 eth0
Of course you would replace the IP address with your default gateways, also the eth0 interface is not always needed!

To manually assign your DNS servers:
echo nameserver 192.168.1.1 > /etc/resolv.conf echo nameserver 212.135.1.36 >> /etc/resolv.conf
Note that the first line will OVERWRITE (>) the resolv.conf file, the second command will APPEND (>>) 'nameserver 212.135.1.36' onto the end of it!

All of this may have been done for you automatically with DHCP anyway, so to check:
cat /etc/resolv.conf
This will display to you the contents of the /etc/resolv.conf file.

To change your DHCP address if it has already been assigned you need to delete the DHCP file assigned to the card:
rm /etc/dhcpc/dhcpcd-eth0.pid
Although that may change based on the interfaces you have!
Then run the dhcpcd command again.


WIRELESS CARDS 

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Wireless cards.
Wireless cards are very different based upon what chipset you have. I personally use Atheros chipset cards which has screwed me up a bit with BackTrack as it has problems with using them for certain attacks.
What I will again show is generic commands for setting up and configuring your wireless interfaces.
The interface name (ath0 below) is entirely dependant on what chipset you are using, you may have any of the following:
ath0 wlan0 wifi0 eth0
You need to find out what you have. To do this you should execute the following bash command:
iwconfig -a
This will show all wireless extension on your machine. You should see all of your network interfaces, but only the wireless ones will have detailed information next to it. Now you know what your wireless cards name is...
Switch on your wireless card:
ifconfig ath0 up
To connect to an 'open' wireless access point (AP):
iwconfig ath0 essid 'nameofnetwork'
The 'nameofnetwork' is your Service Set IDentifer (SSID). That is the name of your network.

To configure a WEP key:
iwconfig ath0 key 3B5D3C7D207E37DCEEEDD301E3

To connect to a specific AP:
iwconfig ath0 ap 03:27:A8:BC:0F:F1
Where '03:27:A8:BC:0F:F1' is the MAC address of your AP, also known as the Basic Service Set IDentifier (BSSID).

Once you have setup your connection, you can get a DHCP address:
dhcpcd ath0

Then check that you have an IP from the wireless network.


To Configure a WPA key:
But what if the network uses WPA? Again you need to assign the essid and maybe an AP MAC, then:
Create a text based file called wpa_supplicant.conf
Enter the following:
""network={ ssid="nameofnetwork" key_mgmt=WPA-PSK proto=WPA pairwise=TKIP group=TKIP psk="WPApassphrase" }
Where nameofnetwork is your ssid and psk is your WPA pre-shared key!

Then run the wpa_supplicant tool.
wpa_supplicant -D madwifi -i ath0 -c wpa_supplicant.conf
This will need altering depending on what chipset and drivers you are using. The above should work for an Atheros card.
Saying all of the above about WPA configurations, I have had many problems with it on BackTrack. If someone else has other suggestions, please post here. Also, please post setup commands for other types of wireless cards.
Alternate Method for WPA key use:
As a pre-thought I have a Dell wireless adapter that uses a Broadcom chipset. I'm using BT2 Final on a USB key.
Create the text based file called wpa_supplicant.conf
Enter the Following: network={

    ssid="nameofnetwork"
    key_mgmt=WPA-PSK
    psk="passkey"

}
where nameofnetwork is the ssid of your network, and passkey is your password.
Make sure your wireless adapter is enabled, and assign your IP, etc addresses if needed. Then run wpa_supplicant. You don't need to assign an essid or MAC AP to your wireless adaptor.
I used wpa_supplicant -ieth0 -cwpa_supplicant.conf -B
Again, replace eth0 with your wireless adapter. If you run iwconfig you should see a key associated with your adapter card.
If you didn't assign any static addresses run your dhcpcd.
dhcpcd eth0
This should have you on the internet in no time. :)
All in all, it turned out with the previous method I was providing too much information at specific points, and that just dumbing down the commands I used made it work consistently. Hopefully, if you've been having problems, this helps.

To put your wireless card into monitor mode:
iwconfig ath0 mode monitor

To restrict it to one specific channel:
iwconfig ath0 channel XX
Make sure you use a two figure number, channel 1 tends to put you on channel 11 for some reason!
Again, they are for Atheros cards, other cards have other commands.


I hope this has helped people in understanding a little more about the configuration settings for their wireless cards. Don't forget the wlassisstant tool on BackTrack too.
Originally posted by Xatar @
http://forums.remote-exploit.org/showthread.php?t=1489

Source: http://backtrack.offensive-security.com/index.php?title=Howto:_How_to_configure_your_Network_Card

Thanks!