164195845 Wireless Networking

Published on January 2017 | Categories: Documents | Downloads: 8 | Comments: 0 | Views: 67
of 7
Download PDF   Embed   Report

Comments

Content

Wireless Networking
Wireless networking is the new face of networking. Wireless networking have been around for many years. Cell phones are also a type of wireless communication and are popular today for people talking to each other worldwide. Wireless networking are not only less expensive than more traditional wired networking but also much easier to install. An important goal of this site is to provide you adequate knowledge for installing a wireless network and get certified in wireless networks as well as. Perhaps you already useing wireless networking in your local coffee shop, at the airport, or in hotel lobbies, and you want to set up a small office or home network. ou already know how great wireless networking is, so you want to en!oy the benefits where you live and work. "t is truly transformational to one#s lifestyle to decouple computing from the wires$ "f you are looking to set up a wireless network, you#ve come to the right place. We will show you the best way to set up wirless network easily. %any people are looking to find out how to use wireless networking at home. "n this wireless networking section we provide An Absolute &eginner#s 'uide provides in the perfect format for easily learning what you need to know to get up to speed with wireless network without wasting a lot of time. (he organi)ation of this site, and the special elements that we have described in this section will help you get the information you need quickly, accurately, and with clarity. "n this section you will find inspiration as well as practical information. we believe that Wireless networks is a modest technology that has the power to have a huge and positive impact.. (his is wonderful material, and it#s lots of fun$ *o what are you waiting for+ "t#s time to 'o for wireless networking.

Wireless Basic
Radio Frequency Transmission Factors
Radio frequencies (RF) are generated by antennas that propagate the waves into the air. Antennas fall under two different categories: directional and omni-directional. irectional antennas are commonly used in point-to-point configurations (connecting two distant buildings)! and sometimes point-to-multipoint (connecting two "#A$s). An e%ample of a directional antenna is a &agi antenna: this antenna allows you to ad'ust the direction and focus of the signal to intensify your range(reach. )mni-directional antennas are used in point-to-multipoint configurations! where they distribute the wireless signal to other computers or devices in your "#A$. An access point would use an omni-directional antenna. *hese antennas can also be used for point-to-point connections! but they lac+ the distance that directional antennas supply

Three main factors influence signal distortion:

• •

Absorption Objects that absorb the RF waves! such as walls! ceilings! and floors Scattering Objects that disperse the RF waves! such as rough plaster on a wall! carpet on the floor! or drop-down ceiling tiles Reflection Objects that reflect the RF waves! such as metal and glass



Responsible body
*he ,nternational *elecommunication -nion-Radio .ommunication /ector (,*-R) is responsible for managing the radio frequency (RF) spectrum and satellite orbits for wireless communications: its main purpose is to provide for cooperation and coe%istence of standards and implementations across country boundaries. Two standards bodies are primarily responsible for implementing W A!s: • "### defines the mechanical process of how "#A$s are implemented in the 012.33 standards so that vendors can create compatible products. The Wi$Fi Alliance basically certifies companies by ensuring that their products follow the 012.33 standards! thus allowing customers to buy "#A$ products from different vendors without having to be concerned about any compatibility issues.



Frequencies bands:
W A!s use three unlicensed bands: • • • • • • 411 567 -sed by older cordless phones 2.8 967 -sed by newer cordless phones! "#A$s! :luetooth! microwaves! and other devices ; 967 -sed by the newest models of cordless phones and "#A$ devices 411 567 and 2.8 967 frequencies are referred to as the ,ndustrial! /cientific! and 5edical (,/5) bands. ; 967 frequency the -nlicensed $ational ,nformation ,nfrastructure (-$,,) band. -nlicensed bands are still regulated by governments! which might define restrictions in their usage.

A hert7 (67) is a unit of frequency that measures the change in a state or cycle in a wave (sound or radio) or alternating current (electricity) during 3 second.

Transmission %ethod
&irect Sequence Spread Spectrum '&SSS( uses one channel to send data across all frequencies within that channel.

.omplementary .ode <eying (..<) is a method for encoding transmissions for higher data rates! such as ;.; and 33 5bps! but it still allows bac+ward compatibility with the original 012.33 standard! which supports only 3 and 2 5bps speeds. 012.33b and 012.33g support this transmission method. OF&% 'Orthogonal Frequency &i)ision %ultiple*ing( increases data rates by using a spread spectrum: modulation. 012.33a and 012.33g support this transmission method. %"%O '%ultiple "nput %ultiple Output( transmission! which uses /// and(or )F 5 by spreading its signal across 38 overlapping channels at ; 567 intervals. 012.33n uses it. -se of 012.33n requires multiple antennas. "#A$ /tandards Standards &ata Rate Throughput Frequency 0ompatibility Range 'meters( !umber of 0hannels Transmission +,-.//a ;8 5bps 2> 5bps ; 967 $one >;@321 > )F 5 +,-.//b 33 5bps 8.> 5bps 2.8 967 +,-.//g ;8 5bps 34 5bps 2.8 967 +,-.//n 280 5bps (with 2=2 antennas) ?8 5bps 2.8 and(or ; 967 012.33a! b! and g ?1@2;1 38 ///()F 5 5,5)

"ith 012.33g and the original "ith 012.33b 012.33 >0@381 -p to 2> /// >0@381 >

*wo 012.33 access modes can be used in a "#A$: • • Ad hoc mode ,nfrastructure mode

Ad hoc mode is based on the ,ndependent :asic /ervice /et (,://). ,n ,://! clients can set up connections directly to other clients without an intermediate AA. *his allows you to set up peer-to-peer networ+ connections and is sometimes used in a /)6). *he main problem with ad hoc mode is that it is difficult to secure since each device you need to connect to will require authentication. *his problem! in turn! creates scalability issues. "nfrastructure mode was designed to deal with security and scalability issues. ,n infrastructure mode! wireless clients can communicate with each other! albeit via an AA. *wo infrastructure mode implementations are in use: • • :asic /ervice /et (://) B%tended /ervice /et (B//)

"n 1SS mode2 clients connect to an AA! which allows them to communicate with other clients or #A$based resources. *he "#A$ is identified by a single //, C however! each AA requires a unique , ! called a :asic /ervice /et ,dentifier (://, )! which is the 5A. address of the AADs wireless card. *his mode is commonly used for wireless clients that donDt roam! such as A.s. "n #SS mode2 two or more ://s are interconnected to allow for larger roaming distances. *o ma+e this as transparent as possible to the clients! such as A As! laptops! or mobile phones! a single //, is used among all of the AAs. Bach AA! however! will have a unique ://, .

Coverage Areas
A "#A$ coverage area includes the physical area in which the RF signal can be sent and received *wo types of "#A$ coverageDs are based on the two infrastructure mode implementations: • • :asic /ervice Area (:/A) B%tended /ervice Area (B/A)

*he terms :// and :/A! and B// and B/A! can be confusing. :// and B// refer to the building topology whereas :/A and B/A refer to the actual signal coverage 1SA "ith :/A! a single area called a cell is used to provide coverage for the "#A$ clients and AA #SA "ith B/A! multiple cells are used to provide for additional coverage over larger distances or to overcome areas that have or signal interference or degradation. "hen using B/A! remember that each cell should use a different radio channel.

Wireless Networking Security SSID and MAC Address Filtering
3ow an end user client with a W A! !"0 accesses a A! • *o allow clients to find the AA easily! the AA periodically broadcasts beacons! announcing its (//, ) /ervice /et ,dentifier! data rates! and other "#A$ information. //, is a naming scheme for "#A$s to allow an administrator to group "#A$ devices together. *o discover AAs! clients will scan all channels and listen for the beacons from the AA(s). :y default! the client will associate itself with the AA that has the strongest signal. "hen the client associates itself with the AA! it sends the //, ! its 5A.

• •



address! and any other security information that the AA might require based on the authentication method configured on the two devices. • • )nce connected! the client periodically monitors the signal strength of the AA to which it is connected. ,f the signal strength becomes too low! the client will repeat the scanning process to discover an AA with a stronger signal. *his process is commonly called roaming.

SS"& and %A0 Address Filtering
"hen implementing //, s! the AA and client must use the same //, value to authenticate. :y default! the access point broadcasts the //, value! advertising its presence! basically allowing anyone access to the AA. )riginally! to prevent rogue devices from accessing the AA! the administrator would turn off the //, broadcast function on the AA! commonly called //, cloa+ing. *o allow a client to learn the //, value of the AA! the client would send a null string value in the //, field of the 012.33 frame and the AA would respondC of course! this defeats the security measure since through this query process! a rogue device could repeat the same process and learn the //, value. *herefore! the AAs were commonly configured to filter traffic based on 5A. addresses. *he administrator would configure a list of 5A. addresses in a security table on the AA! listing those devices allowed accessC however! the problem with this solution is that 5A. addresses can be seen in clear-te%t in the airwaves. A rogue device can easily sniff the airwaves! see the valid 5A. addresses! and change its 5A. address to match one of the valid ones. *his is called %A0 address spoofing.

W#4
"BA ("ired Bquivalent Arivacy) was first security solutions for "#A$s that employed encryption. "BA uses a static E8-bit +ey! where the +ey is 81 bits long! and a 28-bit initiali7ation vector (,F) is used. ,F is sent in clear-te%t. :ecause "BA uses R.8 as an encryption algorithm and the ,F is sent in clear-te%t! "BA can be bro+en. *o alleviate this problem! the +ey was e%tended to 318 bits with the ,F value. 6owever! either variation can easily be bro+en in minutes on laptops and computers produced today.

+,-./* #A4
*he B%tensible Authentication Arotocol (BAA) is a layer 2 process that allows a wireless client to authenticate to the networ+. *here are two varieties of BAA: one for wireless and one for #A$ connections! commonly called BAA over #A$ (BAAo#). )ne of the concerns in wireless is allowing a "#A$ client to communicate to devices behind an AA. *hree standards define this process: BAA! 012.3%! and Remote Authentication ial ,n -ser /ervice (RA ,-/). BAA defines a standard way of encapsulating authentication information! such as a username and password or a digital certificate that the AA can use to authenticate the

user.012.3% and RA ,-/ define how to pac+eti7e the BAA information to move it across the networ+.

W4A
"i-Fi Arotected Access ("AA) was designed by the "i-Fi Alliance as a temporary security solution to provide for the use of 012.3% and enhancements in the use of "BA until the 012.33i standard would be ratified. "AA can operate in two modes: personal and enterprise mode. Aersonal mode was designed for home or /)6) usage. A pre-shared +ey is used for authentication! requiring you to configure the same +ey on the clients and the AA. "ith this mode! no authentication server is necessary as it is in the official 012.3 % standards. Bnterprise mode is meant for large companies! where an authentication server will centrali7e the authentication credentials of the clients.

W4A"AA2 is the ,BBB 012.33i implementation from the "i-Fi Alliance. ,nstead of using "BA! which uses the wea+ R.8 encryption algorithm! the much more secure Advanced Bncryption /tandard (AB/)@counter mode .:.-5A. Arotocol (..5A) algorithm is used.

Types of Wireless Networks W ANS W!ANS WMANS WWANS
A wireless networ5 enables people to communicate and access applications and information without wires. *his provides freedom of movement and the ability to e%tend applications to different parts of a building! city! or nearly anywhere in the world. "ireless networ+s allow people to interact with e-mail or browse the ,nternet from a location that they prefer. 5any types of wireless communication systems e%ist! but a distinguishing attribute of a wireless networ+ is that communication ta+es place between computer devices. *hese devices include personal digital assistants (A As)! laptops! personal computers (A.s)! servers! and printers. .omputer devices have processors! memory! and a means of interfacing with a particular type of networ+. *raditional cell phones donGt fall within the definition of a computer deviceC however! newer phones and even audio headsets are beginning to incorporate computing power and networ+ adapters. Bventually! most electronics will offer wireless networ+ connections. As with networ+s based on wire! or optical fiber! wireless networ+s convey information between computer devices. *he information can ta+e the form of email messages! web pages! database records! streaming video or voice. ,n most cases! wireless networ+s transfer data! such as e-mail messages and files! but advancements in the performance of wireless networ+s is enabling support for video and voice communications as well.

Types of Wireless !etwor5s

W A!S: Wireless ocal Area !etwor5s
"#A$/ allow users in a local area! such as a university campus or library! to form a networ+ or gain access to the internet. A temporary networ+ can be formed by a small number of users without the need of an access pointC given that they do not need access to networ+ resources.

W4A!S: Wireless 4ersonal Area !etwor5s
*he two current technologies for wireless personal area networ+s are ,nfra Red (,R) and :luetooth (,BBB 012.3;). *hese will allow the connectivity of personal devices within an area of about >1 feet. 6owever! ,R requires a direct line of site and the range is less.

W%A!S: Wireless %etropolitan Area !etwor5s
*his technology allows the connection of multiple networ+s in a metropolitan area such as different buildings in a city! which can be an alternative or bac+up to laying copper or fiber cabling.

WWA!S: Wireless Wide Area !etwor5s
*hese types of networ+s can be maintained over large areas! such as cities or countries! via multiple satellite systems or antenna sites loo+ed after by an ,/A. *hese types of systems are referred to as 29 (2nd 9eneration) systems.

0omparison of Wireless !etwor5 Types
Type 0o)erage 4erformanc e Standards "ireless AA$ "ithin reach of a person 5oderate :luetooth! ,BBB 012.3;! and ,r a .able replacement for peripherals ,BBB 012.33! "i-Fi! and 6iper#A$ Applications

"ireless AA$

"ithin reach of a person

5oderate

.able replacement for peripherals

"ireless #A$

"ithin a building or campus

6igh

5obile e%tension of wired networ+s Fi%ed wireless between homes and businesses and the ,nternet 5obile access to the ,nternet from outdoor areas

"ireless 5A$

"ithin a city 6igh

Aroprietary! ,BBB 012.3E! and ",5AH

"ireless "A$

"orldwide

#ow

. A and .ellular 29! 2.;9! and >9

Sponsor Documents

Or use your account on DocShare.tips

Hide

Forgot your password?

Or register your new account on DocShare.tips

Hide

Lost your password? Please enter your email address. You will receive a link to create a new password.

Back to log-in

Close