Chapter 8: Installing Wireless and SOHO Networks Flashcards
The term WiFi refers to wireless networking, in general, but was originally coined for
A term to market 802.11b (Wireless B)
Family of standards that comprise primary wireless networking technology today
IEEE 802.11
WLAN
Wireless LAN
What organization creates and manages wireless standards?
IEEE
Year 802.11 was ratified as a standard
1997
While there are over 20 wireless standards defined in 802.11, what are the most popular?
- 11a
- 11b
- 11g
- 11n
A 802.11 network is similar to a ____ network, only wireless
Ethernet
Just as at the center of an ethernet network there is a central hub, switch, or router, an 802.11 network will have _____
A central, *wireless* hub, switch, or router. Or access point.
SSID
Service-Set Identifier
The public name of a wireless network
Because a wireless network is often one, big collision domain, wireless devices depend on _____ to determine who talks, when, so every device doesn’t send information at the same time.
CSMA / CA
Carrier Sense Multiple Acess / Collission Avoidance
Back-off time
The period of time that a sender waits before attempting to resend a packet of information that experiences a collision with another device’s message.
The original 802.11 standard allows for what speeds and operates at what frequencies?
1Mbps - 2Mbps
Uses the 2.4GHz frequency spectrum
What does the original 802.11 specification used for data encoding?
Either FHSS (Frequency-hopping spread spectrum) or DSSS (Direct-sequence spread spectrum)
802.11a allowed for bandwidth of
54Mbps
What spectrum did 802.11a operate on?
5GHz
What encoding system did the 802.11a standard use?
OFDM (Orthogonal Frequency Division Multiplexing)
When was 802.11a ratified?
1999
Though devices weren’t sold until 2001
Which standard was faster, 802.11a or 802.11b?
- 11a, actually.
- 11b was ratified at the same time as 802.11a but made it to market faster.
What speeds does 802.11b allow for?
11Mbps
What data encoding is used with 802.11b?
DSSS
Why are 802.11b and 802.11a incompatible
These devices cannot be used with each other because they operate at different frequencies.
5GHz and 2.4GHz
When was 802.11g ratified?
2003
What speeds does 802.11g allow for?
54Mbps
What frequency does 802.11g operate on?
2.4GHz
What data encoding is used for 802.11g
OFDM or DSSS
While 802.11g and 802.11b can be used on the same network, what do you give up if you combine the two?
802.11b cannot use OFDM. To compensate, both devices will use DSSS modulation.
All devices connected to either access point will max out at 11Mbps.
Within the 2.4GHz range, there are _____ separate, 22MHz communication channels.
14
Although there are 14 seperate, 22MHz channels on the 2.4GHz range, when using multiple g/b devices, you should select those channels that don’t _____
Overlap
Even though there are 14 defined channels for b/g devices, you can only use ____
The first 11
What are the three non-overlapping channels to use on the 2.4GHz range?
1, 6, 11
When was 802.11n ratified?
2010
What’s the maximum speed for 802.11n?
600Mbps
What frequency range does 802.11n run on?
2.4GHz and 5GHz
What does 802.11n do to achieve its higher throughput/speeds?
40MHz channels instead of 22MHz
MIMO
Channel Bonding
How does 802.11n use 40MHz channels if it uses the same frequency as 802.11g?
The standard reduces the number of channels and doubles the width of each one.
MIMO
Multiple-input multiple-output
Using multiple antennas rather than a single antenna to communicate information
How many antennas can an 802.11n device support?
Up to 8
Channel Bonding
Allows the device to communicate at 2.4GHz and 5GHz simultaneously. A client / network host sends and receives network information at both frequencies.
802.11n is backward compatible with which standards
- 11b
- 11g
- 11a
What is the indoor / outdoor range of
802.11n
Indoor: 70m
Outdorr: 250m
What is the indoor / outdoor range of
802.11g
Indoor: 40m
Outdoor: 140m
What is the indoor / outdoor range of
802.11b
Indoor: 40m
Outdoor 140m
What is the indoor / outdoor range of
802.11a
Indoor: 35m
Outdoor: 120m
What is the indoor / outdoor range of
802.11
Indoor: 20m
Outdoor: 100m
How are distance from an AP and network speeds related?
The closers you are to an AP, the better the connection, the faster the speed.
What are three signal modulation techniques?
FHSS
DSSS
OFDM
FHSS
Frequency-Hopping Spread Spectrum
The sender and receiver “hop” across several predefined frequencies. Both send/receiver switch to a new frequency syncronously.
DSSS
Direct-sequence spread spectrum
Each packet has additional, redundant information (a checksum) to allow the receiver to check that the information was received accurately.
OFDM
Orthogonal frequency division multiplexing
Breaks data into subsinals and transmit them simultaneously on different frequencies / subbands.
Examples of devices that emit signals at the same frequency as wireless APs
Older bluetooth devices
cordless phones
cell phones
other access points
microwaves
WAP
Wireless access point
Look like a wireless router and provide central connectivity like wireless routers, but they don’t have as many features.
….Like, they don’t route packets on a network
Name this device:
Wireless Router
(It says router if you look close enough, which is how you’d tell it apart from a WAP)
Three examples of wireless encryption
WEP
WPA
WPA2
WEP
Wired Equivalency Protocol
Encrypts data using a static key. Clients must know the key.
Keys are usually 10, 26, or 58 hexadecimal characters long.
WEP is insecure because of
The encryption keys are static – never change
the encryption algorithm itself is weak
WPA
WiFi Protected Access
TKIP
Temporal Key Integrity Protocol
Used by WPA
Uses a different 128-bit key for each packet.
WPA2
WiFi Protected Access 2
Uses AES, a much stronger encyption method than WPA’s TKIP
AES
Advanced Encryption Standard
CCMP
Counter Mode CBC-MAC Protocol
Protocol based on AES.
Used by WPA2
SOHO Networks
Small Office / Home Office Networks
Networks based at home or within a small office
ISP
Internet Service Provider
Two categories of Internet Connections
Dial-up
Broadband
POTS
Plain Old Telephone Service
Reasons you might still select dial-up
Only hardware is requires is a modem and a phone connection.
Easy to set up and conifgure
Cheapest solution
Use it whereever there is phone service
DSL
Type of broadband
Digital Subscriber Line
Uses existing phone lines and a DSL modem
List the different forms of DSL
High bit-rate DSL (HDSL)
Symmetric DSL (SDSL)
Very High Bit-rate DSL (VDSL)
Rate-adaptive DSL (RADSL)
Asymmetric DSL (ADSL)
Most popular form of DSL
ADSL
ADSL
Asymmetric DSL
A symmetrical because it supports download speeds that are faster than upload speeds.
Name this device:
The back of a DSL modem
Name this device:
A DSL splitter / filter
Filters out the modem’s noise from the phone line
Why can ADSL and voice operate on the same phone line?
ADSL and voice use different frequencies on the same wire.
Phone communications use frequencies between 0 and 4kHz.
ADSL uses 25kHz - 138kHz
When was the ADSL standard approved?
1998
What was the maximum speed of the first ADSL standard?
8Mbps downloads
1Mbps Upload
What speed doe sthe current ADSL standard offer?
24Mbps download
3.5Mbps upload
Most ADSL communications are ____-duplex
full-duplex
Advantages to DSL
Faster than dial-up
You don’t share your bandwidth with other subscribers
Generally reliable
Naked DSL
DSL via a phone line that doesn’t allow for voice.
Service for people who don’t have land lines
Cable Internet
Internet connection provided via your cable service.
DOCSIS
Data over cable internet specification
Specification that defines how to transfer internet data via a cable connection
Advantages of using cable internet connection
Faster than dial-up. Can be faster than DSL, depending on the service
Not required to have or use a phone line
Generally reliable
Unlike with DSL, when you connect via cable, you ______ with everyone else in your neighborhood
Share a connection
You’re basically connecting to a LAN of your entire neighborhood.
ISDN
Integrated Services Digital Network
A point-to-point network capable of up to 2Mbps
ISDN uses the same 2-pair UTP wiring as ____
POTS
ISDN is still considered _____, even though it’s slower than alternatives
Broadband
Uses a phone line but sends digital (not analog) signals
What does a computer connect to an ISDN line with?
ISDN terminal adapter
Also known as ISDN TA or an ISDN Modem
Even though an ISDN terminal adapter is sometimes refered to as a modem, it isn’t because ____
ISDN is 100% digital. There is no need to convert a digital signal to analog for transmission, or vice versa. Since that’s what a modem does, there isn’t a need for a modem.
Two types of channels of an ISDN line are
Bearer Channel (or B Channel)
Signal Channel (or D Channel)
B Channel
Bearer Channel.
Channel of an ISDN line.
Each bearer channel carries 64Kbps
D Channel
Signal Channel
Type of channel carried by an ISDN line.
Carries 16Kbps
Used for link management, not for carrying data.
BRI ISDN Line
Basic Rate Interface ISDN
Typical type of ISDN line
Speed of a BRI ISDN
144Kbps
Number of B and D channels carried by a BRI ISDN
2 B channels
1 D channels
That’s two 64Kbps channels for data and 1 D channel for link manamagement
A B channel can be used for _____ or data
Voice
When voice is used on a B channel, it cannot be used for data.
2B+D
BRI ISDN
BRI ISDN isn’t popular in the US, but “It’s really big in ____”
Europe
PRI ISDN
Primary Rate Interface ISDN
23 B channels and 1 D channel
Total bandwidth: 1536 Kbps
Carried on a T1
23B + D ISDN
PRI ISDN
FTTH
Fiber to the Home
A type of fiber connection that runs fiber lines from a service provider directly to your home.
FTTN
Fiber to the node
A type of fiber internet conection that runs fiber from the provider to a cable company’s cable box down the street. Then offers copper from the box to your home.
Also known as fiber to the curb
Satellite Internet
Uses a satellite dish to connect you to the Internet.
Often the max speeds are 4Mbps
Comes with latency issues
Problems with satellite internet connections
Installation can be difficult - must be installed and pointed right at the satellite
Line of site between dish and satellite - No trees
Latency - It’s going to space and back
Cables used, max speed, and max distance for
10BaseT Ethernet
UTP CAT3 and up
100Mbps
100Meters (~300 feet)
Cables used, max speed, and max distance for
100BaseTX
UTP CAT5 and up
100Mbps
100 Meters
Cables used, max speed, and max distance for
100BaseFX
Multi-mode fiber
100Mbps
2000 Meters
Cables used, max speed, and max distance for
1000BaseT
UTP CAT5e and higher
1Gbps
100 Meters
Cables used, max speed, and max distance for
10GbaseT
UTP CAT6a and up
10GBps
100 meters
Cables used, max speed, and max distance for
10GBaseSR
Multi-mode fiber
10Gbps
300 meters
Cables used, max speed, and max distance for
10GBaseLR
Single-Mode Fiber
10Gbps
10km (6.2 miles)
Cables used, max speed, and max distance for
10GBaseER
Single-mode fiber
10Gbps
40km (~25 miles)
Between Copper and Fiber, which is not immune to wiretapping
Copper is not immune to wiretapping – It immits a signal and could be listened in on.
Since fiber transmits light, there is no radio signal to pick up.
EMI
Elecromagnetic Interference
Interference caused by radio waves produced by other equipment. Copper cables, which transmit radio waves, can fall victim to EMI
Fiber does not, as it transmits light.
IrDA
Infrared Data Association
Consortium formed in ‘93 to promote / design infrared standards
Infrared data transmission speeds are up to
16Mbps
But IrDA claims faster speeds are coming.
PoE
Power over Ethernet
Providing power to a device by sending it through the CAT-x cable.
Steps to installing a NIC
- Turn of PC, remove case
- Insert NIC expansion card. Screw in
- Put the case on. Power on the PC
- Install the driver
- Plug network cable into NIC
Two ways to give a NIC an IP, subnet mask, default gateway, and DNS server IPs
Use a DHCP server
Assign all that manually
Name this…. thing and it’s use:
Cable Trough
Used to encase cable when running up a wall
Name this item and its use
Floor cable gaurd
So folks don’t trip on cables.
Why should you avoid running cables around fluorescent lights?
These lights create EMI, which will interfere with the signal.
5 steps to securing a wireless router
Change the SSID
Change the administrator username and password
Select AES
Choose a secure passphrase for joining the network
Configure the clients to connect via WPA2
What does disabling the SSID do?
It makes you less vulnerable to casual hackers, but doesn’t increase security in a meaningful way
RADIUS
Remote Authentication Dial-In User Service
Provides centralized authentication services on a network.
How do you configure multiple access points in the same area?
Access point’s coverage should overlap its neighbor by 10% so users don’t lose their signal
Configure the WAPs with the same SSID
Each WAP should broadcast on a channel that does not overlap with it’s neighbor – channels should be 5 channels apart.
WPS
WiFi Protected Setup
A tool for novice users to easily connect to a network by pushing a single button.
In 2011 a security flaw was discovered.
Now that feature is considered insecure.
3 ways to improve security for a wireless router
Disable SSID broadcast
Wireless encryption
MAC filtering
Describe each of the network:
Host-based firewall
Usually a software application.
Firewall that protects a single host
Network-based firewalls
A hardware appliance that protects an entire network or network segment.
Default Deny
A default configuration for most firewalls that disallow all traffic unless explicitely allowed by an admin.
ACL
Access Control List
Set of rules that determines which traffic gets through and which is blocked
Port Triggering
Allowing traffic on a specific port past a firewall, into a network, after a client makes a request on that same port
