Wlan Setup Guide

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WLAN SETUP HOWTO

Naveen.M.K,Protocol Engineering & Technology Unit,

Electrical Engineering Department,Indian Institute of Science,

Bangalore - 12.


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Outline

Introduction Types of WLANs

A Typical WLAN Installation WLAN Hardware 802.11b WLAN Installation in Linux

Ad hoc network

With Access Point


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Introduction WLAN is a wireless local area network that uses

radio waves as its carrier: the last link with the users

is wireless, to give a network connection to all users

in the surrounding area.

Areas may range from a single room to an entirecampus.

The backbone network usually uses cables, with one

or more wireless access points connecting thewireless users to the wired network.


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Types of WLANs

Infrastructure Networks WLAN, Cellular Networks etc.


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Types of WLANs

Infrastructureless Networks MANET


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Types of WLANs Implementation Wise

Ad hoc Mode No Access Point, only mobile nodes

All in one AP

AP with DHCP, mobile nodes Bridge with a DHCP Host

A bridge assisted by a DHCP Server host, mobile nodes

HostAP (All in one Host) Not AP, a host acting as an AP, mobile nodes


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Typical WLAN Installation

WAN/

Internet WLAN Link

WLAN


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Typical WLAN

1 central Access Point Members of the network (mobile or static) All nodes should have a WNIC, (with relevant

drivers installed). AP:

Enable and configure DHCP

Members:

Identify an active AP Register to its LAN using DHCP


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Wireless Hardware

Hardware requirements

Access points

WLAN Cards + Appropriate drivers

Nodes


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Access Points An access point acts as a central hub, router, bridge to Ethernet,

and server for dynamic host configuration protocol (DHCP) andnetwork address translation (NAT), as well as other functions.

The standard home gateways often have a wide area network

(WAN) Ethernet port (to connect to a DSL or cable modem) and

one or more local area network (LAN) ports for the local

network.

Cisco Aironet 1200 series

Linksys 802.11 b/g Wireless router with access points

We have linksys 802.11b BEFW11S4, Etherfast Wireless

AP + Cable/DSL Router with 4 Port Switch


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Linksys BEFW11S4


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Linksys BEFW11S4 Linksys 2.4GHz. EtherFast Wireless Access Point and

Cable/DSL Router with 4 Port Switch Supports up to 32 users

Typical range of up to 100 150 ft. indoors

Connects to a broadband modem, 10/100 Ethernet

backbone or wireless network Eliminates need for an additional hub or switch

Provides roaming, best access point selection, load

balancing and network traffic filtering

Configurable through networked PC's Web browser

Capable of up to 128 bit WEP encryption

Ability to act as DHCP


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Linksys BEFW11S4 Details

Product Type Router Speed 11 Mbps Autodetecting Yes Auto sensing Yes LAN Connection Wireless Wireless Standard 2.4 Ghz System Requirements Linux, Windows 95+.


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Linksys 802.11G AP WAP54G


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Linksys WAP54G

802.11G 54Mbps (interoperable with 802.11b) Advanced wireless security with WPA, 128 bit

WEP encryption, and MAC filtering

All other functionalities are similar to BEFW11S4


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WLAN Cards This card uses a antenna to communicate through microwaves. A

WNIC in a desktop computer is mostly located in theUSB/PCMIA/PCI (can be integrated) slot.

A WNIC can operate in two modes known as infrastructure mode

and ad hoc mode.

Common WLAN Cards Intersil Prism II based cards (available with HostAP mode) (the

most common)

Lucent Orinoco, Samsung (what we have)

Orinoco USB cards and HP/Compaq multiport Cisco Aironet WLAN cards

Realtek RTL8180L cards


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WLAN Cards

802.11gba PCI Card

WLAN PCMCIA Card

Wireless USB Adapter


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Linux Wired & Wireless Extensions

Linux Wired Extensions

ifconfig

dhcp

network Linux Wireless Extensions

/proc/net/wireless

iwconfig

iwlist


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Ifconfig

Ifconfig is used to configure the kernel residentnetwork interfaces. It is used at boot time to set

up interfaces as necessary. After that, it is

usually only needed when debugging or whensystem tuning is needed.

Options:

interface up

down

netmask


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Ifconfig


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Ifconfig


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Ifconfig


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dhcpd and dhclient

dhcpd Dynamic Host Configuration ProtocolServer

Implements the Dynamic Host Configuration

Protocol (DHCP) and the Internet BootstrapProtocol (BOOTP). DHCP allows hosts on a

TCP/IP network to request and be assigned IP

addresses, and also to discover information aboutthe network to which they are attached.

#[PATH TO DHCPD]dhcpd {start|stop|restart|status}


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dhcpd and dhclient

DHCP Client,dhclient, provides a means for

configuring one or more network interfaces using

the Dynamic Host Configuration Protocol,

BOOTP protocol, or if these protocols fail, by

statically assigning an address.

#[PATH TO dhclient]dhclient


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dhclient output


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dhcpd.conf and dhclient.conf

dhcpd.conffile contains configuration information

for dhcpd

Keywords: default lease time, max lease time

subnet, netmask, range, routers

domain name, domain name servers

dh d f dh li f


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dhclient.conffile can be used to configure the behaviour of

the client in a wide variety of ways: protocol timing, information requested from the server information required of the server defaults to use if the server does not provide certain

information values with which to override information provided by the

server,

values to prepend or append to information provided by theserver. The configuration file can also be preinitialized with

addresses to use on networks that don't have DHCP servers.


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Linux Wireless Extensions

/proc/net/wireless is designed to give some

wireless specific statistics on each wireless

interface in the system. This entry is in fact a clone

of /proc/net/dev which gives the standard driver

statistics

/proc/net/wireless


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/proc/net/wireless

For each device, the following information is given :

Status : Its current state. This is a device dependentinformation.

Quality link: general quality of the reception.

Quality level : signal strength at the receiver.

Quality noise : silence level (no packet) at the receiver.

Discarded nwid: number of discarded packets due to

invalid network id.

Discarded crypt: number of packet unable to decrypt

i fi


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iwconfig

This tool is designed to configure all the wireless specific

parameters of the driver and the hardware. This is a clone of

ifconfig used for standard device configuration. Parameters available:

freq or channel: the frequency or the channel sequence nwid: network id or domain, to distinguish different logical

networks

the name of the protocol used on the air

sens: this is the signal level threshold to trigger packet reception

(sensitivity).

enc: the encryption or scrambling key used.

i fi


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iwconfig

iwlist


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iwlist

Get more detailed wireless information from a

wireless interface Used to list currently active access points Options:

scan: Give the list of Access Points and Ad Hoc cells inrange, and optionally a whole bunch of information about

them (ESSID, Quality, Frequency, Mode...).

freq/channel: Give the list of available frequencies in

the device and the number of defined channels.

iwlist example


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iwlist example


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Wireless Network Types

Ad hoc Mode All in one AP AP with a DHCP Host HostAP (All in one Host)

Adhoc Network Setup


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Ad hoc Network Setup A self configuring network of mobile routers (and

associated hosts) connected by wireless linkstheunion of which form an arbitrary topology.

No need of AP

Certain technical knowhow on the part of the useris required to connect to the ad hoc network

The essid has to be distributed (manually or

otherwise) to everyone who wishes to connect tothe adhoc network

Ad hoc Network Setup Steps


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d oc et o Setup Steps iwconfig result



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p p Create a essid

in ad hoc

mode on one

of the mobile

nodes



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p p Associate to

the same essid

in ad hoc

mode on

another

mobile node



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p p Assign an IP address using ifconfig.



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p p Ping to

another

node

13.12.11.1



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Ping to

the other

node

13.12.11.2

Allinone AP


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All in one AP

Using Linksys 802.11b BEFW11S4 as an example. Connect the AP to the computer directly using one of

the 4 switch ports. Access the AP through a browser using a predefined IP

address (the IP address can be found in the manual.) The web interface allows configuration of the AP's

DHCP server, NAT, Security keys, IP forwarding etc as

shown in the following slides.

Main Options & Advanced Options


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Main Options & Advanced Options

Setup Page


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Setup Page

Setup Page


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Setup Page

Password Page


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g

Status Option Page


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p g

DHCP Option Page


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p g

Log Page


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g g

Security Options Page


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y p g

Advanced Options Filters


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Advanced Options Filters


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Forwarding Options Page


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Dynamic Routing


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Static Routing Options Page


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DMZ Host Options Page


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MAC Address Clone


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Wireless Options Page


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Wireless Options Page


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AP + DHCP Host


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AP + DHCP Host

In this network mode the access point acts as a bridge All packets received on one interface are forwarded

to another interface DHCP Host Configuration

dhcpd.conf



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HostAP (All in one Host) Certain WLAN card drivers have been programmed such that when


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Certain WLAN card drivers have been programmed such that when

installed on a computer, the computer can behave as an Access Point.

Such a computer is known as Host AP.

Linux drivers written for wireless LAN cards based on Intersil's

Prism2/2.5/3 chipset currently support host AP facility.

These cards support an inherent HostAP mode.

Three main components of the HostAP project (http://hostap.epitest.fi/)

Host AP Linux driver for Prism2/2.5/3

hostapduser space daemon for access points, including, e.g., IEEE

802.1X/WPA/EAP Authenticator for number of Linux and BSD

drivers, RADIUS client, integrated EAP server, and RADIUS

authentication server

wpa_supplicant user space IEEE 802.1X/WPA supplicant (wireless

client) for number of Linux, BSD, and Windows drivers

HostAP (All in one Host)


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Host AP is a Linux driver for wireless LAN cards based on Intersil's

Prism2/2.5/3 chipset.

Driver supports a Host AP mode it takes care of IEEE 802.11

management functions in the host computer and acts as an access point.

Does not require any special firmware for the wireless LAN card.

In addition to this, it has support for normal station operations in BSSand possible also in IBSS.

WPA and RSN (WPA2) is supported when used with accompanied

tools, wpa_supplicant (WPA/RSN Supplicant) andhostapd(WPA/RSN

Authenticator). All these programs have been designed for both desktop/laptop

computers and embedded systems.

HostAP (All in one Host)


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Intersil's station firmware for Prism2 chipset supports a so called

HostAP mode the firmware takes care of beacon sending and frame acknowledging

leaves other management tasks to host computer driver

This driver implements initialization and configuration of Prism2

based cards, to send and receive frames, and to gather statistics. In addition, it includes an implementation of: authentication (and

deauthentication), association (reassociation, and disassociation),

data transmission between two wireless stations, power saving (PS)

mode signaling and frame buffering for PS stations.

Th k


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Thank you

Questions.

Documents

Wlan Setup Guide