Ahad, 12 Januari 2014
Sport Science: Rehabilitation program for muscle strain and torn ...
Sport Science: Rehabilitation program for muscle strain and torn ...: Bios Patients name Sasi Age 21 Years gender Male Professional athletes Profession Sports Soccer The diagnosis of muscle strain and tor...
Rehabilitation program for muscle strain and torn adductor longus muscle (lower body)
Bios Patients
name Sasi
Age 21 Years
gender Male
Professional athletes Profession
Sports Soccer
The diagnosis of muscle strain and torn adductor longus muscle
No disease history
Physiotherapy treatment 3 times a week (3 weeks ago)
No other activity
Musculoskeletal Report
1. Pain in the anterior hip, especially when walking, sitting and muscle strengthening exercises.
2. ROM decrease in hip flexion, internal rotation, extension and Abduction. Iliopsoas muscle strain, adductors, hamstring and gluteus iliotibial band.
3. Cardiovascular fitness is weak
limit
Pain in the anterior part of the event continued activity, walking or standing (20 minutes)
goals
Sasi want to play again as before without having another injury that befell him. He also wants to lead a normal life without having pain in his entire life to obtain a more comfortable and more confident in life
name Sasi
Age 21 Years
gender Male
Professional athletes Profession
Sports Soccer
The diagnosis of muscle strain and torn adductor longus muscle
No disease history
Physiotherapy treatment 3 times a week (3 weeks ago)
No other activity
Musculoskeletal Report
1. Pain in the anterior hip, especially when walking, sitting and muscle strengthening exercises.
2. ROM decrease in hip flexion, internal rotation, extension and Abduction. Iliopsoas muscle strain, adductors, hamstring and gluteus iliotibial band.
3. Cardiovascular fitness is weak
limit
Pain in the anterior part of the event continued activity, walking or standing (20 minutes)
goals
Sasi want to play again as before without having another injury that befell him. He also wants to lead a normal life without having pain in his entire life to obtain a more comfortable and more confident in life
Jumaat, 1 Jun 2012
Internet Infrastructure
- Infrastructure is the physical hardware used to interconnect users and computer.
- Infrastructure includes the transmission media, software used to receive, send, and manage the signals that are transmitted.
- Infrastructure refers to interconnecting software and hardware and not to computers and other devices that are interconnected.
- For some information technology users, infrastructure is viewed as everything that supports the flow and processing of information.
Internet Protocol (IP):
Defintion: The primary network protocol used on the Internet layer of the Internet Protocol Suite, developed (1970s). On the internet and many other networks. IP is often used together with the Transport Control Protocol (TCP) and referred to interchangeably as TCP/IP.
IP used to supports unique addressing for computers on a network. Almost all networks use the Internet Protocol version 4 (IPv4) standard that features IP addresses four bytes (32 bits) shown as 4octets of number from 1-225 represented in decima form instead of binary in length. Internet Protocol version 6 (IPv6) standard features addresses 16 bytes (128 bits) in length.
- IP specifies the format of packets called datagrams, and the addressing scheme.
- Transmission Control Protocol (TCP), most networks combine IP with higher-level protocol, which establishes a virtual connection between a destination and a source.
- IP consist of two part: network and host/node of network.
- Class of address determines which part belongs to network add and which part belongs node address.
Class A Network
Binary add will start with 0 therefore decimal can be anywhere begin from 1-126.
First octet (8 bits) identify network. For other 3 identify the host.
Class B Network
Binary add will start with 10, so, decimal can be anywhere begin from 128-191.
For decimal 127 reserved for LOPBACK and used for internal testing on local machine.
For the first 2 octet (16bits) identfy network, other 2 octet should be indicate the host.
Class C Network
Binary add will start with 110, so, decimal can be anywhere begin from 192-223.
For the first 3 octet (24 bits) identify network, other 1 should indicate the host.
Class D Network
Binary add will start with 1110 therefore decimal can be anywhere begin from 224-239.
Its used to support multiasking ( multi layers).
Class E Network
Binary add will starts with 1111 therefore decimal can be anywhere from 240-255.
Its used for experimentation.
DOMAIN NAME SYSTEM (DNS)
· DNS, Internet service
that able to translates domain names into
IP addresses. Domain names are alphabetic, its will easier to remember. However, Internet is really based on IP addresses.
·Each time use a domain name, so, a DNS service must translate the name
into the corresponding IP address. For example, the domain name www.example.com should be translate to 198.105.232.4.
·The
DNS system has own network. If one DNS server not able to
translate a particular domain name, its will asks another one, and so on, until the
correct IP address is returned.
· The
Domain Name System makes it possible to assign domain names to
groups of Internet resources and users in a meaningful way, independent of each
entity's physical location.
·Because
of this, World Wide Web (WWW) hyperlinks and
Internet contact information can remain consistent and constant even if the
current Internet routing arrangements change or the participant uses a mobile
device.
·Internet domain names are easier to remember than IP
addresses. Users take advantage of this when they recite meaningful Uniform Resource Locators (URLs) and e-mail
addresses without having to know how the computer actually
locates them.
·DNS
also stores other types of information, such as the list of mail serversthat
accept email for
a given Internet domain. By providing a worldwide, distributed keyword-based
redirection service, the Domain Name System is an essential component of the
functionality of the Internet.
INTERNET ACCESS PROVIDER (ISP)
· An
Internet service provider (ISP) is an organization that provides access to the Internet. Internet service providers can be
either community-ownedand non-profit, or privately owned and for-profit.
·Access
ISPs directly connect clients to the Internet using copper wires,wireless or fiber-optic connections.
·ISP, it
refers to a company that provides Internet services, including personal and
business access to the Internet. For a monthly fee, the service
provider usually provides a software package, username, password and
access phone number.
·Equipped
with a modem, you can then log on to
the Internet and browsethe World Wide Web and USENET,
and send and receive e-mail. For broadband access you typically
receive the broadband modem hardware or pay a monthly fee for this equipment
that is added to your ISP account billing.
·In
addition to serving individuals, ISPs also serve large companies, providing a
direct connection from the company's networks to the Internet. ISPs themselves
are connected to one another through Network
Access Points (NAPs). ISPs may also be called IAPs
(Internet Access Providers).
HTTP
·HTTP stands
for HyperText Transfer Protocol. Hypertext is
a multi-linear set of objects, building a network by using logical links (the
so calledhyperlinks) between the nodes (e.g.
text or words).
·HTTP
is the protocol to exchange or transfer hypertext.
·It’s
what browsers and web servers rely on for exchanging data so that you can surf
the web, browse web pages, search Google, download pictures, and viewing
YouTube.
·Developed
by W3C and IETF in
the last few years of the last century, it’s part of a bigger protocol family
created to support the whole Internet, called TCP/IP. As a subset, HTTP’s
responsibility is the World Wide Web or WWW.
·By
HTTP definition and usage, it’s fundamentally an information exchanging
procedure standard between 2 communicating parties or computers, such as the
client and the server.
·While
you type a URL address in the web browser, the browser will have to know the
protocol to use when fetching the remote resource such as a web page or a
picture at that address. Failing to do so, as we most of the time would do
without the http:// part, the browser will assume HTTP by default and
prepend it to the URL address.
A
web address representing an access point on the web almost always start with
http://, immediately followed by the web page address such as in this one
‘http://www.google.com/’.
·This
is the root web site address of Google. And browsing to it, the server located
at the address would serve up the home page of Google. This is all beyond the
meaning of HTTP however, what this basically means is that, a web address
consists of 2 basic parts: Protocol (HTTP) & Address (WWW.GOOGLE.COM).
Isnin, 14 Mei 2012
Wireless Networking
Wireless networking overview
- NETGEAR products conform to the Institute of Electronics Engineers (IEEE).
- 802.11g standard for wireless LANs.
- 802.11 wireless link, data is encoded using direct-sequence spread-spectrum (DSSS) technology, transmitted in the unlicensed radio spectrum at 2.5 GHz.
- 54Mbps is maximum data rate for the 802.11g wireless link, also will automatically back down from 54Mbps when the radio is weak and interference is occur.
- 802.11 standard ( Wireless Ethernet or Wi-Fi ) by the Wireless Ethernet Compatibility Alliance (WECA, see http://www.wi-fi.net), an industry standard group promoting interoperability among 802.11 standard offers two methods for configuring a wireless network- ad hoc infrastructure.
Infrastructure mode
- Wireless access point, the wireless LAN can operate in the infrastructure mode.
- This mode lets you connect wirelessly to wireless network devices within a area of coverage.
- The access point has one or more antennas that allow you to interact with wireless nodes.
- The wireless access point converts airwave data into wired Ethernet data, acting as a bridge between the wireless LAN and wireless clients.
- Connecting multiple access points via a wired Ethernet backbone can further extend the wireless network coverage.
- As a mobile computing device moves out of the range of one access point, it moves into the range of another.
- As a result, wireless clients can freely roam from one access point domain to another and still
maintain seamless network connection.
Ad Hoc mode ( Peer-to-peer Workgroup)
- Computers are brought together as needed.
- The network has no structure or fixed points- each node can be set up to communicate with any other node.
- No access point is involved in this configuration.
- This mode enables you to quickly set up a small wireless workgroup and allows workgroup members to exchange data or share printers as supported by Microsoft® networking in the various Windows® operating systems.
- Some vendors also refer to ad hoc networking as peer-to-peer group networking.
- Network packets are directly sent and received by the intended transmitting
and receiving stations.
- As long as the stations are within range of one another, this is the easiest
and least expensive way to set up a wireless network.
Network name - Extended Service Set Identification (ESSI)
- One of two types of Service Set Identification (SSID).
- In an ad hoc wireless network with no access points, the Basic Service Set Identification
(BSSID) is used.
- In an infrastructure wireless network that includes an access point, the ESSID is used, but may still be referred to as SSID.
- An SSID is a 32-character (maximum) alphanumeric key identifying the name of the wireless local
area network.
- Some vendors refer to the SSID as the network name. For the wireless devices in a
network to communicate with each other, all devices must be configured with the same SSID.
Wireless Channel
- IEEE 802.11g/b wireless nodes communicate with each other using radio frequency signals in the
ISM (Industrial, Scientific, and Medical) band between 2.4 GHz and 2.5 GHz.
- Neighboring channels are 5 MHz apart.
- Due to the spread spectrum effect of the signals, a node sending signals using a particular channel will utilize frequency spectrum 12.5 MHz above and below the center channel frequency.
- Two separate wireless networks using neighboring channels (for example, channel 1 and channel 2) in the same general vicinity will interfere with each other.
- Applying two channels that allow the maximum channel separation will decrease the
amount of channel cross-talk and provide a noticeable performance increase over networks with
minimal channel separation.
- The available channels supported by wireless products in various countries are
different.
• Regulations in the United States prohibit using channels greater than channel 11.
• For NETGEAR products sold outside the United States, the wireless region
selection determines which channels are available for use in the product.
- The preferred channel separation between the channels in neighboring wireless networks is
25 MHz (five channels).
- This means that you can apply up to three different channels within your
wireless network. In the United States, only 11 usable wireless channels are available, so we
recommended that you start using channel 1, grow to use channel 6, and add channel 11 when
necessary, because these three channels do not overlap.
Key Size and Configuration
The IEEE 802.11 standard supports two types of WEP encryption: 40-bit and 128-bit.
- The 64-bit WEP data encryption method allows for a five-character (40-bit) input.
- 24 factory-set bits are added to the forty-bit input to generate a 64-bit encryption key. (The 24 factory set
bits are not user-configurable).
- This encryption key will be used to encrypt/decrypt all data transmitted via the wireless interface.
- Some vendors refer to the 64-bit WEP data encryption as 40-bit WEP data encryption because the user-configurable portion of the encryption key is 40 bits wide.
- The 128-bit WEP data encryption method consists of 104 user-configurable bits.
-Similar to the 40- bit WEP data encryption method, the remaining 24 bits are factory-set and not user-configurable.
- Some vendors allow pass phrases to be entered instead of the cryptic hexadecimal characters to
ease encryption key entry.
- The 128-bit encryption is stronger than 40-bit encryption, but 128-bit encryption may not be
available outside the United States due to U.S. export regulations.
- When configured for 40-bit encryption, 802.11 products typically support up to four WEP keys.
- Each 40-bit WEP key is expressed as five sets of two hexadecimal digits (0–9 and A–F). For
example, “12 34 56 78 90” is a 40-bit WEP key.
- When configured for 128-bit encryption, 802.11g products typically support four WEP keys, but
some manufacturers support only one 128-bit key.
- The 128-bit WEP Key is expressed as 13 sets of two hexadecimal digits (0–9 and A–F). For example, “12 34 56 78 90 AB CD EF 12 34 56 78 90” is a 128-bit WEP key.
- Typically, 802.11 access points can store up to four 128-bit WEP keys, but some 802.11 client
adapters can only store one.
- Make sure that your 802.11 access and client adapters configurations match.
-Whatever keys you enter for an access point, you must also enter the same keys for the client
adapter in the same order.
How to Use WEP Parameters
- WEP data encryption is used when the wireless devices are configured to operate in Shared Key authentication mode.
- Before enabling WEP on an 802.11 network, you must first consider what type of encryption you require and the key size you want to use.
-There are three WEP Encryption options available for 802.11 products:
• Do Not Use WEP: The 802.11 network does not encrypt data. For authentication purposes, the network uses Open System Authentication.
• Use WEP for Encryption: A transmitting 802.11 device encrypts the data portion of every packet it sends using a configured WEP key. The receiving 802.11g device decrypts the data using the same WEP key. For authentication purposes, the 802.11g network uses Open System Authentication.
• Use WEP for Authentication and Encryption: A transmitting 802.11 device encrypts the data portion of every packet it sends using a configured WEP key. The receiving 802.11 device
decrypts the data using the same WEP key. For authentication purposes, the 802.11 network uses Shared Key Authentication.
-Wi-Fi Protected Access (WPA) is a specification of standards-based, interoperable security enhancements that increase the level of data protection and access control for existing and future wireless LAN systems.
- WPA offers the following benefits:
• Enhanced data privacy
• Robust key management
• Data origin authentication
• Data integrity protection
How Does WPA Compare to WEP?
- WEP is a data encryption method and is not intended as a user authentication mechanism.
- WPA user authentication is implemented using 802.1x and the Extensible Authentication Protocol (EAP).
- Support for 802.1x authentication is required in WPA.
- In the 802.11 standard, 802.1x authentication was optional. Refer to IETF RFC 2284.
- With 802.11 WEP, all access points and client wireless adapters on a particular wireless LAN must use the same encryption key.
- A major problem with the 802.11 standard is that the keys are
cumbersome to change.
- If you do not update the WEP keys often, an unauthorized person with a sniffing tool can monitor your network for less than a day and decode the encrypted messages.
- Products based on the 802.11 standard alone offer system administrators no effective method to update the keys.
- For 802.11, WEP encryption is optional. For WPA, encryption using Temporal Key Integrity
- Protocol (TKIP) is required. TKIP replaces WEP with a new encryption algorithm that is stronger than the WEP algorithm, but that uses the calculation facilities present on existing wireless devices to perform encryption operations.
- TKIP provides important data encryption enhancements
including a per-packet key mixing function, a message integrity check (MIC) named Michael, an extended initialization vector (IV) with sequencing rules, and a re-keying mechanism.
- Through these enhancements, TKIP addresses all known WEP vulnerabilities.
How Does WPA Compare to IEEE 802.11i?
- WPA is forward-compatible with the IEEE 802.11i security specification currently under development.
- WPA is a subset of the current 802.11i draft and uses certain pieces of the 802.11i draft that were ready to bring to market in 2003, such as 802.1x and TKIP.
- The main pieces of the 802.11i draft that are not included in WPA are secure IBSS (Ad-Hoc mode), secure fast handoff
(for specialized 802.11 VoIP phones), as well as enhanced encryption protocols such as AESCCMP.
- These features are either not yet ready for market or will require hardware upgrades to implement.
What are the Key Features of WPA Security?
The following security features are included in the WPA standard:
• WPA Authentication.
• WPA Encryption Key Management.
– Temporal Key Integrity Protocol (TKIP).
– Michael message integrity code (MIC).
– AES Support.
• Support for a Mixture of WPA and WEP Wireless Clients.
Definition: 802.11a wireless network communication standard. One of the IEEE standards in the 802.11 series.
802.11a and wireless Interference
- 802.11g standard for wireless LANs.
- 802.11 wireless link, data is encoded using direct-sequence spread-spectrum (DSSS) technology, transmitted in the unlicensed radio spectrum at 2.5 GHz.
- 54Mbps is maximum data rate for the 802.11g wireless link, also will automatically back down from 54Mbps when the radio is weak and interference is occur.
- 802.11 standard ( Wireless Ethernet or Wi-Fi ) by the Wireless Ethernet Compatibility Alliance (WECA, see http://www.wi-fi.net), an industry standard group promoting interoperability among 802.11 standard offers two methods for configuring a wireless network- ad hoc infrastructure.
Infrastructure mode
- Wireless access point, the wireless LAN can operate in the infrastructure mode.
- This mode lets you connect wirelessly to wireless network devices within a area of coverage.
- The access point has one or more antennas that allow you to interact with wireless nodes.
- The wireless access point converts airwave data into wired Ethernet data, acting as a bridge between the wireless LAN and wireless clients.
- Connecting multiple access points via a wired Ethernet backbone can further extend the wireless network coverage.
- As a mobile computing device moves out of the range of one access point, it moves into the range of another.
- As a result, wireless clients can freely roam from one access point domain to another and still
maintain seamless network connection.
Ad Hoc mode ( Peer-to-peer Workgroup)
- Computers are brought together as needed.
- The network has no structure or fixed points- each node can be set up to communicate with any other node.
- No access point is involved in this configuration.
- This mode enables you to quickly set up a small wireless workgroup and allows workgroup members to exchange data or share printers as supported by Microsoft® networking in the various Windows® operating systems.
- Some vendors also refer to ad hoc networking as peer-to-peer group networking.
- Network packets are directly sent and received by the intended transmitting
and receiving stations.
- As long as the stations are within range of one another, this is the easiest
and least expensive way to set up a wireless network.
Network name - Extended Service Set Identification (ESSI)
- One of two types of Service Set Identification (SSID).
- In an ad hoc wireless network with no access points, the Basic Service Set Identification
(BSSID) is used.
- In an infrastructure wireless network that includes an access point, the ESSID is used, but may still be referred to as SSID.
- An SSID is a 32-character (maximum) alphanumeric key identifying the name of the wireless local
area network.
- Some vendors refer to the SSID as the network name. For the wireless devices in a
network to communicate with each other, all devices must be configured with the same SSID.
Wireless Channel
- IEEE 802.11g/b wireless nodes communicate with each other using radio frequency signals in the
ISM (Industrial, Scientific, and Medical) band between 2.4 GHz and 2.5 GHz.
- Neighboring channels are 5 MHz apart.
- Due to the spread spectrum effect of the signals, a node sending signals using a particular channel will utilize frequency spectrum 12.5 MHz above and below the center channel frequency.
- Two separate wireless networks using neighboring channels (for example, channel 1 and channel 2) in the same general vicinity will interfere with each other.
- Applying two channels that allow the maximum channel separation will decrease the
amount of channel cross-talk and provide a noticeable performance increase over networks with
minimal channel separation.
- The available channels supported by wireless products in various countries are
different.
• Regulations in the United States prohibit using channels greater than channel 11.
• For NETGEAR products sold outside the United States, the wireless region
selection determines which channels are available for use in the product.
- The preferred channel separation between the channels in neighboring wireless networks is
25 MHz (five channels).
- This means that you can apply up to three different channels within your
wireless network. In the United States, only 11 usable wireless channels are available, so we
recommended that you start using channel 1, grow to use channel 6, and add channel 11 when
necessary, because these three channels do not overlap.
WEP
Wireless Security
-
The absence of a physical connection between nodes
makes the wireless links vulnerable to eavesdropping and information theft.
-
To provide a certain level of security, the IEEE
802.11 standard has defined two types of authentication.:
-
Open
System authentication, a wireless computer can join any network and receive
any messages that are not encrypted.
The following steps occur when two devices
use Open System Authentication:
1. The station sends an authentication
request to the access point.
2.
The access point authenticates the station.
3.
The station associates with the access point and joins the network.
-
Shared Key authentication, only those computers that
possess the correct authentication key can join the network.
The following steps occur when two devices
use Shared Key Authentication:
1. The station sends an authentication
request to the access point.
2. The access point sends challenge text to
the station.
3. The station uses its configured 64-bit
or 128-bit default key to encrypt the challenge text, and it sends the
encrypted text to the access point.
4. The access point decrypts the encrypted
text using its configured WEP key that corresponds to the station’s default
key. The access point compares the decrypted text with the original challenge
text. If the decrypted text matches the original challenge text, then the
access point and the station share the same WEP key, and the access point
authenticates the station.
5. The station connects to the network.
Key Size and Configuration
The IEEE 802.11 standard supports two types of WEP encryption: 40-bit and 128-bit.
- The 64-bit WEP data encryption method allows for a five-character (40-bit) input.
- 24 factory-set bits are added to the forty-bit input to generate a 64-bit encryption key. (The 24 factory set
bits are not user-configurable).
- This encryption key will be used to encrypt/decrypt all data transmitted via the wireless interface.
- Some vendors refer to the 64-bit WEP data encryption as 40-bit WEP data encryption because the user-configurable portion of the encryption key is 40 bits wide.
- The 128-bit WEP data encryption method consists of 104 user-configurable bits.
-Similar to the 40- bit WEP data encryption method, the remaining 24 bits are factory-set and not user-configurable.
- Some vendors allow pass phrases to be entered instead of the cryptic hexadecimal characters to
ease encryption key entry.
- The 128-bit encryption is stronger than 40-bit encryption, but 128-bit encryption may not be
available outside the United States due to U.S. export regulations.
- When configured for 40-bit encryption, 802.11 products typically support up to four WEP keys.
- Each 40-bit WEP key is expressed as five sets of two hexadecimal digits (0–9 and A–F). For
example, “12 34 56 78 90” is a 40-bit WEP key.
- When configured for 128-bit encryption, 802.11g products typically support four WEP keys, but
some manufacturers support only one 128-bit key.
- The 128-bit WEP Key is expressed as 13 sets of two hexadecimal digits (0–9 and A–F). For example, “12 34 56 78 90 AB CD EF 12 34 56 78 90” is a 128-bit WEP key.
- Typically, 802.11 access points can store up to four 128-bit WEP keys, but some 802.11 client
adapters can only store one.
- Make sure that your 802.11 access and client adapters configurations match.
-Whatever keys you enter for an access point, you must also enter the same keys for the client
adapter in the same order.
How to Use WEP Parameters
- WEP data encryption is used when the wireless devices are configured to operate in Shared Key authentication mode.
- Before enabling WEP on an 802.11 network, you must first consider what type of encryption you require and the key size you want to use.
-There are three WEP Encryption options available for 802.11 products:
• Do Not Use WEP: The 802.11 network does not encrypt data. For authentication purposes, the network uses Open System Authentication.
• Use WEP for Encryption: A transmitting 802.11 device encrypts the data portion of every packet it sends using a configured WEP key. The receiving 802.11g device decrypts the data using the same WEP key. For authentication purposes, the 802.11g network uses Open System Authentication.
• Use WEP for Authentication and Encryption: A transmitting 802.11 device encrypts the data portion of every packet it sends using a configured WEP key. The receiving 802.11 device
decrypts the data using the same WEP key. For authentication purposes, the 802.11 network uses Shared Key Authentication.
WPA Wireless Security
- WPA offers the following benefits:
• Enhanced data privacy
• Robust key management
• Data origin authentication
• Data integrity protection
How Does WPA Compare to WEP?
- WEP is a data encryption method and is not intended as a user authentication mechanism.
- WPA user authentication is implemented using 802.1x and the Extensible Authentication Protocol (EAP).
- Support for 802.1x authentication is required in WPA.
- In the 802.11 standard, 802.1x authentication was optional. Refer to IETF RFC 2284.
- With 802.11 WEP, all access points and client wireless adapters on a particular wireless LAN must use the same encryption key.
- A major problem with the 802.11 standard is that the keys are
cumbersome to change.
- If you do not update the WEP keys often, an unauthorized person with a sniffing tool can monitor your network for less than a day and decode the encrypted messages.
- Products based on the 802.11 standard alone offer system administrators no effective method to update the keys.
- For 802.11, WEP encryption is optional. For WPA, encryption using Temporal Key Integrity
- Protocol (TKIP) is required. TKIP replaces WEP with a new encryption algorithm that is stronger than the WEP algorithm, but that uses the calculation facilities present on existing wireless devices to perform encryption operations.
- TKIP provides important data encryption enhancements
including a per-packet key mixing function, a message integrity check (MIC) named Michael, an extended initialization vector (IV) with sequencing rules, and a re-keying mechanism.
- Through these enhancements, TKIP addresses all known WEP vulnerabilities.
How Does WPA Compare to IEEE 802.11i?
- WPA is forward-compatible with the IEEE 802.11i security specification currently under development.
- WPA is a subset of the current 802.11i draft and uses certain pieces of the 802.11i draft that were ready to bring to market in 2003, such as 802.1x and TKIP.
- The main pieces of the 802.11i draft that are not included in WPA are secure IBSS (Ad-Hoc mode), secure fast handoff
(for specialized 802.11 VoIP phones), as well as enhanced encryption protocols such as AESCCMP.
- These features are either not yet ready for market or will require hardware upgrades to implement.
What are the Key Features of WPA Security?
The following security features are included in the WPA standard:
• WPA Authentication.
• WPA Encryption Key Management.
– Temporal Key Integrity Protocol (TKIP).
– Michael message integrity code (MIC).
– AES Support.
• Support for a Mixture of WPA and WEP Wireless Clients.
Definition: 802.11a wireless network communication standard. One of the IEEE standards in the 802.11 series.
802.11a and wireless Interference
- 802.11a transmit radio signals in the frequency range above 5 GHz, a part of wireless spectrum regulated in many countries.
- Regulation means 802.11a gear generally avoids signal interference from other consumer wireless products like cordless phones.
- In contrast, 802.11b/g utilizes frequencies inthe unregulated 2.4 GHz range and is more susceptible to radio interference from other devices
Range of 802.11a networks
- Helps improve network performance and reduce interference the range of an 802.11a signal is limited by use of the high 5 GHz frequency.
- An 802.11a access point transmitter may cover less than one-fourth the area of a comparable 802.11 b/g unit.
- Brick walls and other obstructions affect 802.11a wireless networks to a greater degree than they do comparable 802.11b/g networks.
Selasa, 24 April 2012
Network cabling
Type of cable:
Unshielded twisted pair
Coaxial cable
Fiber Optic
Unshielded twisted pair characteristics:
Coaxial Cable Connecter:
single mode :
Unshielded twisted pair
Coaxial cable
Fiber Optic
Unshielded twisted pair characteristics:
-Unshielded .
-least expensive cable.
-Twisted pairs of .insulated conductors.
-Covered by insulating sheath.
-Radio and electrical frequency interference (should not be too close to electric motors, fluorescent lights.
Each pair is twisted with a different number of twist per inch to help eliminate interference from adjacent pairs and other electrical devices.
The tighter the twisting, the higher the supported transmission rate and the greater the cost per foot.
Cat5e cable:
-1000Mbps data capacity.
-For runs of up to 90 meters.
-Solid core cable ideal for structural
installations (PVC or Plenum).
-Stranded cable ideal for patch cables.
RJ-45 connectors:
-Terminated with RJ-45 connectors (plastic connector).
-RJ - Registered Jack, implying that the connector follows a standard borrowed from the telephone industry.
-This standard designates which wire goes with each pin inside the connector.
-Best option for school networks.
RJ-45 connectors
Shielded Twisted Pair (STP) Cable:
-Shielded twisted pair may be the solution for the interference of UTP connectors.
- Help to extend the maximum distance of the cables
- Available in three different configurations:
Each pair of wires is individually shielded with foil.
There is a foil or braid shield inside the jacket covering all wires (as a group).
There is a shielded around each individual pair, as well as around the entire group of wires (referred to as double twisted pair).
Coaxial Cable:
-Single copper conductor at its center.
-A plastic layer provides insulation between the center conductor and a
braided metal shield
-The metal shield helps to block any
outside interference from fluorescent lights, motors, and others computer.
-Difficult to install.
-Highly resistant to signal interference.
-Support greater cable lengths between network devices than twisted pair
cable.
-Thick coaxial and thin coaxial.
Thin coaxial:
-Also called thinnet.
-10Base2 refers to the specifications for thin coaxial cable carrying
Ethernet signals.
-2 refers to the approximate maximum segment length being 200 meters.
-Maximum segment length is 185 meters.
-popular in school networks, especially
linear bus networks.
Thick coaxial :
-Also called thicknet.
-The 5 refers to the maximum segment length being 500 meters.
-has an extra protective plastic cover that helps keep moisture away from
the center conductor.
-Great choice when running longer lengths in a linear bus network.
-One disadvantage does not bend easily and is difficult to
install.
- Common type of connector used is the Bayone-Neill-Concelman (BNC) connector.
Fiber Optic Cable:
-Center glass core surrounded by several layers of protective .
-Transmits light rather than electronic signals eliminating the problem
of electrical interference.
-Environments a large amount of electrical interference.
-Made it the standard for connecting
networks between buildings, due to its immunity to the effects of moisture and
lighting.
-To transmit signals over much longer distances than coaxial and twisted
pair.
-Carry information at vastly greater speeds.
-Capacity broadens communication possibilities to include services such
as video conferencing and interactive services.
-The cost ofvis comparable to copper cabling;
however, it is more difficult to install and modify.
-10BaseF refers to the specifications for
fiber optic cable carrying Ethernet signals.
-center core of is made from glass or plastic fibers.
-A plastic coating then cushions the fiber center, and kevlar fibers help
to strengthen the cables and prevent breakage.
-Can provide more distance, but it is more
expensive.
Multimode :
-larger diameter; however, both cables provide high bandwidth at high
speeds.
Specification
|
Cable Type
|
10BaseT
|
Unshielded Twisted Pair
|
10Base2
|
Thin Coaxial
|
10Base5
|
Thick Coaxial
|
100BaseT
|
Unshielded Twisted Pair
|
100BaseFX
|
Fiber Optic
|
100BaseBX
|
Single mode Fiber
|
100BaseSX
|
Multimode Fiber
|
1000BaseT
|
Unshielded Twisted Pair
|
1000BaseFX
|
Fiber Optic
|
1000BaseBX
|
Single mode Fiber
|
1000BaseSX
|
Multimode Fiber
|
Making connection:
-RJ45 connectors
-Cable stripper
-Scissors
-Crimping tool
Making connection steps:
Installing Cable - some guidelines
-Test every part of a network as you install it. Even if it is brand new, it may have problems that will be difficult to isolate later.
-Stay at least 3 feet away from fluorescent light boxes and other sources of electrical interference.
-If it is necessary to run cable across the floor, cover the cable with cable protectors.
-Label both ends of each cable.
-Use cable ties (not tape) to keep cables in the same location together.
1.Strip cable end
- Strip 1 – 1½” of insulating sheath.
-Avoid cutting into conductor insulation.
2.Untwisted wire ends.
-Sort wires by insulation colors.
4.Trim wires to size.
lTrim all wires evenly
lLeave about ½” of wires exposed
lTrim all wires evenly
lLeave about ½” of wires exposed
Installing Cable - some guidelines
When running cable, it is best to follow a few simple
rules:
-Always
use more cable than you need. Leave plenty of slack.-Test every part of a network as you install it. Even if it is brand new, it may have problems that will be difficult to isolate later.
-Stay at least 3 feet away from fluorescent light boxes and other sources of electrical interference.
-If it is necessary to run cable across the floor, cover the cable with cable protectors.
-Label both ends of each cable.
-Use cable ties (not tape) to keep cables in the same location together.
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