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Fundamentals of Networking. Discovery 1, Chapter 7. Objectives. Describe wireless technology Describe the various components & structure of a wireless LAN Describe wireless security issues and mitigation strategies Configure an integrated wireless access point and wireless client.

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Fundamentals of Networking

Discovery 1, Chapter 7


  • Describe wireless technology

  • Describe the various components & structure of a wireless LAN

  • Describe wireless security issues and mitigation strategies

  • Configure an integrated wireless access point and wireless client

Wireless Technologies

Understanding Wireless

  • Electromagnetic Spectrum

    • Radio, TV, Light, X-Rays, Gamma Rays

    • Each has a specific wavelength

      • Like the distance between waves

  • Wireless uses Electromagnetic Waves

    • Same as carrying radio signals

  • We’ll discuss the most common wavelengths

Infrared (IR)

  • Low energy

  • Can’t go through walls, short range (30’)

    • Line of sight

  • One to one communication

    • Wireless Mice & Keyboards, Remotes, PDA

    • Infrared Direct Access (IrDA) port

IR & Your TV

  • Your TV remote has an infrared LED inside

  • Switches on & off to create 0’s and 1’s when you push a button

    • Push a button to send a 7 digit sequence of 0’s & 1’s

    • Sony TV Channel Up is 0000011, channel down is 0010001

Radio Frequency (RF)

  • Wireless LAN, cordless phone, Bluetooth

  • LAN & Phone

    • Signal travels through walls, longer range, higher power

    • 900 MHz, 2.4 GHz and the 5 GHz frequency

  • Bluetooth

    • Low speed, short range, lower power

    • One to many devices

    • Uses 2.4GHz

    • Starting to use Bluetooth for wireless mice, etc.

Activity- Which is it?


  • Bluetooth or RF. Which has higher power output?

    • RF

  • Two doctors are beaming their business cards to each other through their PDAs. Which signal is being used?

    • IR

Wireless Benefits

Wireless Limitations

  • Many devices use wireless

    • Cordless Phones 2.4GHz Interference

    • Microwave Ovens Interference

    • Range

    • Solid Walls a problem

  • Not as fast as, or reliable as, wired

  • Security

    • Wireless is east to access & can be intercepted

      • Authentication & Encryption now used

Types of Wireless Networks

  • WWAN

  • WLAN

  • WPAN

Wireless Personal Area Network

Used to connect wireless mice, keyboards & PDA’s to computer

IR or Bluetooth

Short Range

Device to device

Peer to peer



  • Wireless Local Area Network

    • RF

    • IEEE 802.11 standards

    • Users connect to a wired network through an Access Point (AP)

    • Medium range

Access Point

  • Between your wired equipment and your wireless devices


  • Wireless Wide Area Network

    • Cell phone network

    • GSM, CDMA

    • Long range

    • Government regulated

Wireless Networks


Wireless LANs

Wireless Standards

  • Specifies data speed, range, RF spectrum

  • IEEE standards, Wi-Fi

  • 802.11a, 802.11b, 802.11g and 802.11n

  • Wi-Fi Alliance tests devices from manufacturer

  • Will work with other devices w/ same logo


  • 1999

  • 2.4GHz

  • 11Mbps

  • 150ft range indoors

  • 300 ft range outdoors


  • 1999

  • 5GHz

    • Unused at that time

    • Less congestion

  • 54Mbps (faster than B)

  • NOT compatible with b/g/n

  • 75ft-150ft range

  • Originally too expensive

  • Now hard to find


  • 2003

  • 2.4GHz

  • 54Mbps

  • 150ft range indoors

  • 300 ft range outdoors

  • Compatible with 802.11b


  • 2.4Ghz

  • Up to 750ft range

  • Backwards compatible b/g

Wireless Components

  • Access Point

    • Connects wireless devices to wired network

  • Client

    • Any host device that connects to wireless

    • Also known as STA (station)

  • Bridge

  • Antenna

Omni-Directional Antenna

  • Equally in all directions

  • Found on APs

Directional Antenna

  • Concentrate signal in one direction

  • Better distance

  • Connects networks 25 miles or more apart

  • Bridge to Bridge- connects 2 networks wirelessly

Want a bridge? Aironet 1400

  • Find it on


WLANs & the SSID

  • Your WLAN has to be identified

SSID-Service Set Identifier

  • Tells wireless devices which WLAN they belong to & which other devices they can communicate with

  • Case-sensitive & up to 32 characters

  • All of your devices MUST have same SSID

    • Broadcast or Not?

WLAN Install 1:Ad-hoc Mode- IBSS

  • Wireless devices can talk to each other without involving Access Point

  • Peer-to-peer or small networks

  • Less $$$, no AP

WLAN Install 2: Infrastructure Mode- BSS

  • Most used

  • AP/Router controls communication

    • Access to Internet

    • Basic Service Set (BSS)

      • Area covered by a single AP

Cover More Areas

  • Connect many BSS’s to get expanded area

    • You get an ESS, Extended Service Set

  • Areas should overlap

    • Think about this school & coverage





Lab Activity


    • Setting the SSID on an AP


  • Click Topology, then the host

  • View browser, follow directions

Used to control multiple conversations

Like how all of your TV channels travel across a cable

Divides up the 2.4GHz for each conversation

Selection of channels is usually automatic

Sometimes they use a single wide channel to get more bandwidth

Wireless Channels

Going to a Concert

  • General Admission compared to tickets for a seat

    • What’s the different experiences?

  • Wireless has a method to avoid collisions

  • A “ticketing” system

Wireless Detecting Collisions


  • Reserves a channel for conversation

    • No one else may use that channel

  • Request to Send (RTS) to the AP

  • If available, a Clear to Send (CTS) is sent

    • OK to send

    • Broadcast is sent to all, notifying channel in use

  • ACK sent to AP to notify done

    • All devices see ACK & know channel is open


Activity- Setting the Channel


    • Most of the time, automatic is fine

Configuring an AP

Configuring the Client

  • What is a wireless host known as?

    • STA (station)

  • It’s a device with wireless NIC & software for it

  • Settings MUST match AP

    • SSID, security settings, and channel

As part of the OS

OR supplied with Wireless NIC

Contains link info, profiles, etc.

Usually the OS one is okay

Configuring the Client- Software

Look at signal strength

Then test data transmission

Use the ping test

Ping another PC 1st

If that doesn’t work, ping the AP

Now Test It…

Lab &

  • Configure the AP and Wireless Client

  • Test

Security on Wireless LANs

Wireless Security

  • Tradeoff:

    • Ease & convenience of availability vs. putting info to the airwaves

  • What can they do?

    • Use your Internet for FREE

    • Access your computers

    • Damage files

    • Steal private info

  • Solution…SET UP SECURITY!

Why is security important?

  • It’s possible that an individual or a business owner can be held responsible for what an unauthorized user does with your network

  • Computer Fraud Law

    • Accessing a computer without authorization

Getting In Easily

Take Security Measures

  • Use all of the following to secure your wireless network:

    • Change the router password from the default

    • Change the SSID & disable the broadcast

    • Use MAC Address Filtering

    • Authentication (PSK)

    • Encryption (WPA)

Wireless Security

Change Router Password!

Change the Password!

Wireless Security

Change SSID & Disable Broadcast!

Change SSID & Disable Broadcast

  • Problem

    • SSID must be known to connect

    • Broadcast by default

  • Solution


    • Change the default settings

      • SSID

      • Passwords

      • IP addresses

    • These solutions help, but you can still be hacked!

The SSID’s- Discovered!!!

Wireless Security

MAC Address Filtering!

Get your MAC Addresses

Set up MAC Address Filtering

MAC Address Filtering

  • Use your device’s MAC address to limit connectivity to you KNOWN devices

  • You pre-configure the MACs in the AP

  • The AP will check its list

  • Only those in list will connect

MAC Address Filtering

  • What could go wrong?

    • Typo on the MAC address

    • New devices can’t enter network without adding Mac to the AP configuration

    • MAC address cloning

      • Sniff network traffic (MAC address in packet)

      • Find MAC addresses on that network

      • Change your MAC address to match one on the target network.

Sniffing to Clone

Wireless Security

Authenticate & Encrypt!

Authentication to the AP

  • Permitting entry to network

    • Like username & password

    • Works with encryption methods

  • Occurs before client connects to WLAN

  • 3 types:

    • Open (Default)

    • PSK (Used at home)

    • EAP (Used at big businesses)

Open Authentication

  • Default

  • Anyone can connect

Pre-Shared Keys (PSK) Authentication

  • AKA “Personal”

  • Same passphrase set on AP & Client

  • Client asks AP to connect

    • One way

Pre-Shared Keys (PSK) Authentication

  • AKA “Personal”

  • Same passphrase (or key) set on AP & Client

  • Client asks AP to connect

    • One way

EAP Authentication (Enterprise)

  • Two-way PLUS username/password

  • Talks to RADIUS server

    • Has database of allowed clients

    • In medium to large businesses

Authentication & MAC Filter

  • Authenticate 1st

  • MAC Filtering 2nd

  • These hacker from gaining access only!


  • Protect data traveling through the air

  • Prevents signal from being intercepted

    • “Sniffing”

  • WEP

  • WPA Personal (WPA-PSK; WPA Personal)

  • WPA2 Personal (WPA2-PSK; WPA2 Personal)


  • Wired Equivalency Protocol

    • All devices use same WEP key

    • 64 or 128 bits long

    • Set up using a passphrase

      • Generates Key 1 to use

    • WEAK!!!! Same static key


  • Wi-Fi Protected Access

    • 64 to 256 bits long

    • New key each time client connects to AP

    • Pick how it encrypts

      • TKIP (Temporal Key Integrity Protocol)

      • AES (Advanced Encryption System)


  • WEP/WPA _______________ the data.

    • Encrypt

  • PSK/EAP are used to _____________ the user to the WLAN.

    • Authenticate

  • WEP or WPA. Which is stronger?

    • WPA

  • What’s the difference between open authentication & PSK?

    • PSK has the secret key

Configure encryption and authentication


You can control the type of data

Entering or leaving the AP

Going to/from a specific MAC or IP

Block by port #


Access Restrictions



  • Configuring Wireless Security

Planning & Installing the WLAN

Planning the WLAN

  • Determining the type of wireless standard to use

  • Determining the most efficient layout of devices

  • An installation and security plan

  • A strategy for backing up and updating the firmware of the wireless devices.

Wireless Standard

  • Bandwidth requirements, coverage areas, existing implementations, and cost.

    • This information is gathered by determining end-user requirements.

  • Ask the following…

    • What throughput is actually required by the applications running on the network?

    • How many users will access the WLAN?

    • What is the necessary coverage area?

    • What is the existing network structure?

    • What is the budget?

Planning the WLAN

  • Which 802.11 standards support a larger BSS?

    • Means less equipment to buy

  • Is there an existing standard in use?

  • Total Cost of Ownership (TCO) which includes the purchase of the equipment as well as installation and support costs

Installation of Devices

  • Site Survey

    • Measurements

    • Consider interference sources & locations

Install & Secure the AP

Back It Up!!! Activity

  • Home & Small Business

    • Select Backup Configuration in Menu

    • To restore, select it

    • Factory Default Setting

Updating the Firmware

  • The OS of the device is in firmware

    • Update for new features, etc

  • Get the current version

  • Research issues & features that may cause you to want the upgrade

  • Download it to a HD (directly connected machine)

  • Select Firmware upgrade


  • Upgrade the firmware


Advanced Review

Fundamentals of Networking

Discovery 1, Chapter 7

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