AUTHOR: Dr. Edgar Alwers <edgaralwers@gmx.de>
DATE: 2006-12-10
LICENSE: GNU Free Documentation License Version 1.2
SYNOPSIS: Wireless Communication from the sources
PREREQUISITES:
BLFS 6.x with kernel 2.6.18
DESCRIPTION:
This is a Hint explaining how to prepare a PC for wireless communication with
the Internet and how to put it into operation. I solved this problem with the
help of hints and advices given by many persons, and working through lots of
papers, many of them not beeing actual anymore at this time.
The object I had to deal with is an 'Acer' TravelMate 291LCi with Intel Centrino
Mobile Technology, equiped with an Intel PRO/Wireless 2200BG(IEEE 802.11b/g)
chip. The Laptop communicates with an 54 Mbps Wireless Netgear ADSL Firewall
Router DG834G as access point However, there are good chances, that this hint
may also be applied to other PC's with other drivers. If you cannot obtain a
native Linux driver for your wireless NIC, you may want to try 'ndiswrapper', a
package that will allow to load a Windows driver under Linux.
The kernel compiled is version 2.6.18. This kernel includes already an 'old'
driver ipw2200 and a iee802 subsystem, which should not be enabled, as they are
beeing provided separate.
Additional instructions are given, how to operate a PC in a wireless field under
a DHCP Server ( Dynamic Host Configuration Protocol ) providing IP's to the
clients. This is the probably situation which will be found in most public
locations, like airports, hotels etc.
HINT:
KERNEL
Download:
Kernel v. 2.6.18
http://www.kernel.org
Configuring the kernel:
enable Networking->
Networking support->
Networking options->
Packet socket
TCP/IP networking
device drivers->
Network device support->
Wireless LAN (non-harmradio)->
Wireless LAN drivers & Wireless Extensions
cryptographic optionsI->
ARC4 cipher algorithm (Modul)
Make sure, that the following capabilities are not enabled:
networking->
Generic IEE 802.11 Networking Stack
device drivers->
Network device support->
Wireless LAN ( non-hamradio ) ->
Intel PRO/Wireless 2200BG and
2915ABG network
compile and install the kernel according to the instructions of the book 'Linux
From Scratch'
HOTPLUG-2004_09_23
Scripts that react upon hotplug events generated by the kernel
Download:
hotplug-2004_09_23.tar.bz2
http://www.kernel.org/pub/linux/utils/kernel/hotplug
Install hotplug issuing a 'make install' in the untared directory.
IEE80211-1.2.15
Kernel subsystem dealing with communications security
Download
ieee80211-1.1.15.tgz
http://ieee80211.sourceforge.net
Untar the file, change to the ieee80211-1.1.15 directory and enter make, make
install.
Includes headerfiles in /lib/modules/2.6.18/net
INTEL'S PRO/WIRELESS DRIVER AND FIRMWARE
Download the file
ipw2200_linux_1_2_0.tgz
http://ipw2200.sourceforge.net
Unter the file. Two new tar files will be included in the new created
'intel_ipw2200_120' directory: ipw2200-1.2.0.tgz, the PRO/Wireless driver, and
ipw2200-fw-3.0.tgz, the firmware.
Untar the firmware file in the directory /lib/firmware. Four files
ipw-2200-xxx.fw will be found there after untaring
Untar the PRO/Wireless driver file, change to the ipw2200-1.2.0 directory and
enter make, make install. ( as su )
The driver requires the firmware image as well as the ieee80211 module
installed. sysfs should be already mounted
See also the INSTALL file for more instructions
THE WIRELESS TOOLS
Set of tools that allows to manipulate Wireless Extensions
Download the wireless tools:
wireless_tools.28.tar.gz
http://pcmcia-cs.sourceforge.net/ftp/contrib/
Untar the file, change to the wireless_tools.28 directory and enter make, make
install
Seven tools will be installed in /usr/local/sbin: iwconfig, iwlist,
ifrename,iwevent,iwgetid, iwpriv and iwspy
Make a link from KDE_Prefix/bin to /usr/local/sbin:
ln -s /usr/local/sbin/iwconfig KDE_Prefix/bin/iwconfig
THE DHCPCD CLIENT SOFTWARE
Software to connect a computer to a network which uses DHCP to assign network
addresses.There are two alternatives: dhcp, which includes also the server
software, and dhcpcd, an implementation of the DHCP client specified in RFC2131.
I prefered dhcpcd, wich seems to be more simple.
Download
dhcpcd-2.0.8.tar.bz2
http://prdownload.berlios.de/dhcpcd/
Untar, change to the dhcpcd-2.0.8 directory and enter
./configure --prefix="" --mandir=/usr/share/man
make
and, as superuser, make install, and
chmod -v 754 /etc/dhcpc/dhcpcd.exe.
The reason for the prefix "" in the configuration command is explained in the
blfs-book, version svn-20061028, chapter 14.
Install the network service script
/etc/sysconfig/network-devices/services/dhcpcd and create
/etc/sysconfig/network-devices/ifconfig.eth1/dhcpcd configuration file as
indicated in the same place
BOOTING THE PC
If everything went right, the PC boots and loads firmware and wireless-driver.
The corresponding booting messages will look like
........
ieee80211_crypt: registered algorithm 'NULL'
ieee80211: 802.11 data/management/control stack, 1.1.6
ieee80211: Copyright (C) 2004-2005 Intel Corporation
<jketreno@linux.intel.com>
ipw2200: Intel(R) PRO/Wireless 2200/2915 Network Driver, 1.0.8
ipw2200: Copyright(c) 2003-2005 Intel Corporation
ACPI: PCI Interrupt Link [LNKG] enabled at IRQ 10
ACPI: PCI Interrupt 0000:01:02.0[A] -> Link [LNKG] -> GSI 10 (level,
low) -> IRQ 10
ipw2200: Detected Intel PRO/Wireless 2200BG Network Connection
Detected geography ZZM (11 802.11bg channels, 0 802.11a channels)
.........
MONITORING PROGRAMS
There are many prrograms that allows the monitoring of wireless communications.
I installed two of them: 'Wireshark' ( former ethereal ) and 'KWiFiManager'.
'wireshark' is a powerfull network protocol analyser ( packet sniffer ).
Download 'wireshark-0.99.4.tar.gz' from http://www.wireshark.org/download/src
Untar the file and run ./configure, make and make install.
'kwifimanager' is a KDE frontend program used to configure and monitor wireless
LAN cards. 'kwifimanager' is part of 'kdenetwork'. Download
kdenetwork_3.4.1.tar.bz2 and follow the instructions given e.g. In BLFS -
Version 6.1, chapter 29. Wireless tools should be installed before building this
packet.
CONFIGURING THE ROUTER - SAFETY CONSIDERATIONS
during the installation of the wireless system, the safety options of the router
are deactivated. Now, it is time to activate them. Access the settings menu of
the router through a browser, entering something like http://192.168.0.1. I
activated WEP ( Wired Equivalent Privacy ) with 64 bit encryption. You may
consider a 125 bit encryption
Enter a password in the encryption field, and the router will generate four
keys, each one consisting of 10 characters, combining numbers 1 to 9 and letters
A-F, like:EC670531BE. The first of this four keys is the one beeing normally
used.
Furthermore, the MAC-addresses ( Media Access Control ) of the laptop's and PC's
wich are allowed to access the router shoud be entered in the access list
'trusted wireless stations'. You may get the MAC addresses from the list of
connected devices in the settings menu of the router or with the help of a
network exploration tool like 'nmap' ( Network Mapper ), in the last case e.g.
entering 'nmap -sP 192.168.0.1/22'
However, even a 125 bit encryption does not give a real security today.
According to a note contributed by Bryan Kadzban, real security can only be
obtained with WPA or WPA2 encryption. You may want to consider this, if you have
confidential data to transmit.
CONFIGURING THE PC FOR WIRELESS COMMUNICATIONS
immediately after the safety options of the router are activated, the PC will
not more be able to see the access point: the PC also needs to be configured.
Entering the command 'iwconfig eth1 key xxxxxxxxxx' enables the communication,
but not permanently. For a permanent configuration, write a shell-script
e.g.'connect' in /etc/rc.d/init.d:
$!/bin/sh
/usr/local/sbin/iwconfig eth1 key xxxxxxxxxx
and make this script executable: chmod ug+x connect. Make a symbolic link in
/etc/rc.d/rc3.d that points to this script: ln -s /etc/rc.d/init.d/connect
S19connect. The link should start with something like S19, as the script should
be run before the S20network script is executed. For an unencrypted system,
likely to be found on public places, the command in the script should not
contain a key:
/usr/local/sbin/iwconfig eth1
Create a directory 'ifconfig.eth1' in '/etc/sysconfig/network-devices', and cd
to this directory.
For operation withouth DHCP create a ipv4 file:
ONBOOT=yes
SERVICE=ipv4-static
IP=192.168.1.3 // the address of your box
GATEWAY=192.168.1.9 // the address of your router
PREFIX=24
BROADCAST=192.168.1.255
NETMASK=255.255.255.0
and change GATEWAY_IF in /etc/sysconfig/network to eth1.
For operation with DHCP create instead ipv4 a file dhcpcd:
ONBOOT="no"
SERVICE="dhcpcd"
DHCP_START="eth1 -t 20"
DHCP_STOP="-k "
# Set PRINTIP="yes" to have the script print
# the DHCP assigned IP address
PRINTIP="yes"
# Set PRINTALL="yes" to print the DHCP assigned values for
# IP, SM, DG, and 1st NS. This requires PRINTIP="yes".
PRINTALL="no"
USING THE WIRELESS CONNECTION
After booting, lsmod shows
Module Size Used by
ipw2200 170244 0
ieee80211 45356 1 ipw2200
ieee80211_crypt 4512 1 ieee80211_crypt_wep,
ieee80211
The command 'iwconfig eth1' entered in a console delivers
eth1 IEEE 802.11g ESSID:"Mannheim"
Mode:Managed Frequency:2.462 GHz Access Point:
00:0A:B5:CF:64:28
Bit Rate=48 Mb/s Tx-Power=20 dBm Sensitivity=8/0
Retry limit:7 RTS thr:off Fragment thr:off
Encryption key:57E4-DB3A-B1 Security mode:open
Power Management:off
Link Quality=95/100 Signal level=-29 dBm Noise level=-86 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
As the ONBOOT parameter was set to 'yes', the connection to the access point is
already activ.
The internet browser should be configured with direct access to the internet.
Opening the browser should establish immediately a connection.
USING THE WIRELESS CONNECTION UNDER A DHCP SERVER
I experienced some problems starting the dhcpcd daemon during the boot process.
So I decided to set the ONBOOT parameter in the file
/etc/sysconfig/network-devices/ifconfig.eth1/dhcpcd to 'no', as indicated above,
and to start as 'su' a little script 'eth1_connect' :
#!/bin/bash
/sbin/dhcpcd eth1
# end
After starting the daemon dhcpcd, the connection to the access point is activ.
AKNOWLEDGEMENTS:
I have tryed to compile articles, informations, hints and answers to questions I
put in the BLFS-mailing list to this hint. Many thanks to all those who
contributed: Gabe Yoder, Andrew Benton, Alexander E. Patrakov, Jim Gifford,
David Fix, Rainer Peter Feller, Chris Staub, Randy McMurchy,
Jeremy Monnet, Stefan Krah, Bryan Kadzban.
LINKS AND LITERATURE:
Intel PRO/Wireless driver
http://ipw2200.sourceforge.net
Linux Wireless Networking
http://www.linuxhomenetworking.com/linux-hn/wmp11-linux.html
Wireless LAN Resources for Linux
http://www.hpl.hp.com/personal/jean_Tourrilhes/Linux/Tools.html
Wiresharkt
http://www.wireshark.org/
The devices, the drivers... Jean Tourrilhes
http://www.hpl.hp.com/personal/jean_Tourrilhes/Linux/Linux.Wireless.drivers.802.
1.11ag.html#CentrinoAG
Sane network interface management with Hotplug. Jean Tourrilhes
http://www.hpl.hp.com/personal/jean_Tourrilhes/Linux/HOTPLUG.txt
ndiswraper
http://ndiswrapper.sourceforge.net/mediawiki/index.php/Installation
CHANGELOG:
[2006-03-26]
Remarks concerning safety considerations
Additional notes concerning DHCP-Server operation
Chapter "The DHCPCD Client Software"
Configuring the PC for operation under DHCP
Subsystem IEE80211-1.1.6 changed to IEE80211-1.1.12
Intel PRO/WIRELESS driver ipw2200-1.0.8 changed to ipw2200-1.0.10
Using the wireless connection under a DHCP server
[2006-12-10]
Kernel version 2.6.18
Kernel configuration changed
Hotplug instructions changed
UDEV is now part of the system
ieee80211 version changed to 1.2.15
New versions of Intel's PRO/Wireless driver and firmware
Wireless tools version 28
dhcpcd version 2.0.8
new message booting the PC
'Kismet' skipped, 'wireshark' introduced
Links and literature changed