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Redes Inalámbricas – Tema 2.C Wireless LANs: the IEEE standards

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1 Redes Inalámbricas – Tema 2.C Wireless LANs: the IEEE 802.11 standards
The 802 wireless family IEEE The physical layer The MAC layer Quality of service: e MIMO: n Management tools

2 Redes Inalámbricas – Tema 2.C Wireless LANs: the IEEE 802.11 standards
The 802 wireless family IEEE The physical layer The MAC layer Quality of service: e MIMO: n Management tools

3 IEEE 802 Active Working Groups and Study Groups
802.1 Higher Layer LAN Protocols Working Group Link Security Executive Committee Study Group is now part of 802.1 802.3 Ethernet Working Group Wireless LAN Working Group Wireless Personal Area Network (WPAN) Working Group Broadband Wireless Access Working Group Resilient Packet Ring Working Group Radio Regulatory TAG Coexistence TAG Mobile Broadband Wireless Access (MBWA) Working Group Media Independent Handoff Working Group Wireless Regional Area Networks

4 Historical notes The IEEE Working Group for WLAN Standards was created in 1997: Defines the MAC and 3 different physical layers that work at 1Mbps and 2Mbps: Infrared (IR) in base band Frequency hopping spread spectrum (FHSS), band de 2,4 GHz Direct sequence spread spectrum (DSSS), band de 2,4 GHz IEEE Std b (September 1999): Extension of DSSS; Up to 11 Mbps IEEE Std a (December 1999): A different physical layer (OFDM): Orthogonal frequency domain multiplexing Up to 54 Mbps IEEE Std g (June 2003) ...

5 Evolution of the IEEE 802.11 standard
OFFICIAL IEEE WORKING GROUP PROJECT TIMELINES IN PROCESS  - Standards, Amendments, and Recommended Practices 802.11p: Inter car communications Communication between cars/road side and cars/cars Planned for relative speeds of min. 200km/h and ranges over 1000m Usage of GHz band in North America 802.11s: Mesh Networking Design of a self-configuring Wireless Distribution System (WDS) based on Support of point-to-point and broadcast communication across several hops 802.11r: Faster Handover between BSS Secure, fast handover of a station from one AP to another within an ESS Current mechanisms (even newer standards like i) plus incompatible devices from different vendors are massive problems for the use of, e.g., VoIP in WLANs Handover should be feasible within 50ms in order to support multimedia applications efficiently

6 Evolution of the IEEE 802.11 standard
Other interesting groups 802.11t: Performance evaluation of networks Standardization of performance measurement schemes 802.11v: Network management Extensions of current management functions, channel measurements Definition of a unified interface 802.11w: Securing of network control Classical standards like , but also i protect only data frames, not the control frames. Thus, this standard should extend i in a way that, e.g., no control frames can be forged. Note: Not all “standards” will end in products, many ideas get stuck at working group Standards are available here:

7 IEEE and WiFi Wi-Fi is a set of standards for wireless networks based on IEEE specifications. Wi-Fi is a trademark of the Wi-Fi Alliance (formerly the Wireless Ethernet Compatibility Alliance), the trade organization that tests and certifies that equipments meet the IEEE x standards. The main problem which is intended to solve through normalization is compatibility. This means that the user is assured that all devices having the seal Wi-Fi can work together regardless of the manufacturer of each. A complete list of devices that have the certification Wi-Fi:

8 Redes Inalámbricas – Tema 2.C Wireless LANs: the IEEE 802.11 standards
The 802 wireless family IEEE The physical layer The MAC layer Quality of service: e MIMO: n Management tools

9 Spread Spectrum Transmission

10 Comparison of Wireless Modulation Schemes
FHSS transmissions less prone to interference from outside signals than DSSS WLAN systems that use FHSS have potential for higher number of co-location units than DSSS DSSS has potential for greater transmission speeds over FHSS Throughput much greater for DSSS than FHSS Amount of data a channel can send and receive

11 Orthogonal Frequency Division Multiplexing (OFDM)
With multipath distortion, receiving device must wait until all reflections received before transmitting Puts ceiling limit on overall speed of WLAN OFDM: Send multiple signals at same time High number of low BW ‘modems’ are used, each on a different sub channel The ‘slow’ sub channels are multiplexed into a ‘fast’ combined channel Error correction is done with FEC and bit stripping Avoids problems caused by multipath distortion Used in a networks

12 Notion of a channel Signal Power
It is common knowledge that wireless communication happens over a fixed set of frequencies, called a channel. Such a system makes efficient use of such spectrum while allowing for multiple parties to communicate on orthogonal or independent channels. This figure shows the power spectral density of a transmission, or which frequency is being utilized with how much aggregate output power. Wireless communication is carried over a set of frequencies called a channel Thanks to: Mishra, Shrivastava, Banerjee, and Arbaugh, The University of Wisconsin, Madison

13 Available spectrum is typically divided into disjoint channels
Channels in Wireless Channel A Channel B Channel C Channel D Fixed Block of Radio Frequency Spectrum Given a fixed amount of RF spectrum, communication engineers divide it up into disjoint channels. Each channel carries some communication traffic independent of the rest. The capacity of the wireless Available spectrum is typically divided into disjoint channels Thanks to: Mishra, Shrivastava, Banerjee, and Arbaugh, The University of Wisconsin, Madison

14 Ideal Spectrum Usage Channel A Channel B Power Frequency Use entire range of frequencies spanning a channel Usage drops down to zero right outside a channel Thanks to: Mishra, Shrivastava, Banerjee, and Arbaugh, The University of Wisconsin, Madison

15 Realistic Spectrum Usage
Channel A Channel B Real Usage Wastage of spectrum In reality, this is what communication circuits can achieve Results in inefficient usage of spectrum Thanks to: Mishra, Shrivastava, Banerjee, and Arbaugh, The University of Wisconsin, Madison

16 Realistic Spectrum Usage
Channel A Channel B Real Usage Wastage of spectrum Is it possible to eliminate such inefficiencies ? Thanks to: Mishra, Shrivastava, Banerjee, and Arbaugh, The University of Wisconsin, Madison

17 Define a new channel Define a new channel as shown
Channel B Channel A’ Define a new channel as shown Overlaps with neighboring two channels Called a `partially overlapped’ channel Thanks to: Mishra, Shrivastava, Banerjee, and Arbaugh, The University of Wisconsin, Madison

18 Define a new channel Channel A’ would interfere with both A and B
Channel B Channel A’ Channel A’ would interfere with both A and B Is it possible to get any gains from using A, A’ and B ? Thanks to: Mishra, Shrivastava, Banerjee, and Arbaugh, The University of Wisconsin, Madison

19 802.11b Channels In the UK and most of EU: 13 channels, 5MHz apart, – GHz Each channel is 22MHz Significant overlap Best channels are 1, 6 and 11

20 An 802.11 Experiment Amount of Interference
Can we use channels 1, 3 and 6 without interference ? Link A Ch 1 Link C Ch 6 Link B Ch 3 Ch 1 Ch 3 Ch 6 Amount of Interference Thanks to: Mishra, Shrivastava, Banerjee, and Arbaugh, The University of Wisconsin, Madison

21 An 802.11 Experiment 35 meters 60 meters Link A Ch 1 Link B Ch X
Thanks to: Mishra, Shrivastava, Banerjee, and Arbaugh, The University of Wisconsin, Madison

22 IEEE 802.11b Data rate Transmission range Frequency Security
1, 2, 5.5, 11 Mbit/s, depending on SNR User data rate max. approx. 6 Mbit/s Transmission range 300m outdoor, 30m indoor Max. data rate ~10m indoor Frequency Free 2.4 GHz ISM-band Security Limited, WEP insecure, SSID Availability Many products and vendors Connection set-up time Connectionless/always on Quality of Service Best effort, no guarantees (unless polling is used, limited support in products) Manageability Limited (no automated key distribution, sym. Encryption) Pros Many installed systems and vendors Available worldwide Free ISM-band Cons Heavy interference on ISM-band No service guarantees Relatively low data rate

23 IEEE 802.11a Data rate Transmission range Frequency Security
6, 9, 12, 18, 24, 36, 48, 54 Mbit/s, depending on SNR User throughput (1500 byte packets): 5.3 (6), 18 (24), 24 (36), 32 (54) 6, 12, 24 Mbit/s mandatory Transmission range 100m outdoor, 10m indoor E.g., 54 Mbit/s up to 5 m, 48 up to 12 m, 36 up to 25 m, 24 up to 30m, 18 up to 40 m, 12 up to 60 m Frequency Free , , GHz ISM-band Security Limited, WEP insecure, SSID Availability Some products, some vendors Connection set-up time Connectionless/always on Quality of Service Best effort, no guarantees (same as all products) Manageability Limited (no automated key distribution, sym. Encryption) Pros Fits into 802.x standards Free ISM-band Available, simple system Uses less crowded 5 GHz band Higher data rates Cons Shorter range

24 IEEE 802.11g Ratified in June 2003 by the IEEE Standards Board
standard preliminary draft submitted in December 2001; Uses the 2.4 GHz band OFDM and codification PBCC Backward compatibility IEEE b They can co-exist in the same WLAN New transmission speeds: 6, 9, 12, 18, 24, 36, 48 & 54 Mbps

25 Examples of the physical parameters of a real deviceal
DATA SHEET of a Cisco Aironet a/b/g CardBus Wireless LAN Client Adapter

26 WiFi and health RFR's biological effects are measured in terms of specific absorption rate (SAR) -- how much energy is absorbed into human tissue -- which is expressed in Watts per kilogram (W/kg). A dangerous level (by U.S. standards) is considered to be anything above 0.08 W/kg. Thus far, RFR measurements for Wi-Fi, both at home and abroad, are a minute fraction of emissions that could amount to this level. Wi-Fi, in fact, emits less than other common sources of RFR like microwaves and mobile phones. Since mobile phones were recently cleared as a potential carcinogen by a comprehensive, long-term study conducted by the Danish Institute of Cancer Epidemiology in Copenhagen, it seems very unlikely that devices emitting a lower (and less frequent) level could be more dangerous. By Naomi Graychase, January 12, 2007 More information:

27 Redes Inalámbricas – Tema 2.C Wireless LANs: the IEEE 802.11 standards
The 802 wireless family IEEE The physical layer The MAC layer Quality of service: e MIMO: n Management tools

28 Available architectures
Independent Basic Service Set (IBSS) is the simplest of all IEEE networks in that no network infrastructure is required. As such, an IBSS is simply comprised of one or more Stations which communicate directly with each other. Do not confuse it with ad hoc!! infrastructure Basic Service Set (BSS) Components: Station (STA) Access Point (AP) or Point Coordinator (PC) Basic Service Set (BSS) Extended Service Set (ESS)

29 The MAC basics CSMA/CA with binary exponential backoff
The protocol, at its minimum, consists of two frames: data and ack Point Coordination Function (PCF) Distributed Coordination Function (DCF) MAC Services without contention Services with The 5 timing values: Slot time SIFS: short interframe space (< slot time) PIFS: PCF interframe space (=SIFS+1slot) DIFS: DCF interframe space (=SIFS+2slots) EIFS: extended interframe space DIFS PIFS SIFS Contention window defer access busy medium slot

30 DCF example The backoff intervals are chosen within the contention window. That is in the interval [0, CW] The CW can vary between 31 slots (CWmin) and 1023 slots (CWmax) CW increases after a failed transmission and re-initialized after a successful transmission B1 = 25 B2 = 20 B1 = 5 B2 = 15 data wait data wait B2 = 10 B1 and B2 are the backoff intervals in STA 1 and 2 CW = 31

31 A couple of problematic configurations
Exposed node Hidden node A A B C B C D

32 Hidden nodes situations
MU3 cannot hear MU1 or MU2 because of the distance The obstacle prevents MU1 and MU2 from hearing one another

33 RTS/CTS mechanism Based on the network allocation vector (NAV) source
DIFS+contention source RTS data SIFS SIFS SIFS destination CTS ACK DIFS Other STA NAV (RTS) Contention window NAV (CTS) defer access

34 PCF: Point Coordination Function
Data+Poll DATA+ACK Beacon ACK Station 2 sets NAV(Network Allocation Vector) CF-End PIFS SIFS (no response) CP PC STA1 Contention Free Period STA2 NAV Reset Time STA3 Station 3 is hidden to the PC, it does not set the NAV. It continues to operate in DCF. The beacons are used to maintain synchronization of the timers in the stations and to send control information The AP generates the beacons at regular intervals The stations know when the next beacon will arrive the target beacon transmission time (TBTT) are announced in the previous beacon

35 Frames structure management (00) control (01), data (10),
Types of addresses: Source address (SA) Destination Address (DA) Transmitter Address (TA) Receiver Address (RA) BSS identifier (BSSID) management (00) control (01), data (10), reserved (11) SA DA TA RA 1 Wireless DS - RA = BSSID To the AP BSSID RA = DA From the AP IBSS Addr. 4 Addr. 3 Addr. 2 Addr. 1 From DS To DS Función

36 Addressing and DS bits AP Client Client Server Server DS RA (BSSID) TA
SA/TA AP AP SA RA Client AP DA Client DA Server Server SA DA TA RA 1 Wireless DS - RA = BSSID To the AP BSSID RA = DA From the AP IBSS Addr. 4 Addr. 3 Addr. 2 Addr. 1 From DS To DS Función

37 Services The IEEE 802.11 architecture defines 9 services
Station services: Authentication Deauthentication Privacy  WEP Data delivery Distribution services: Association  generate a connection between a STA and a PC Disassociation Reassociation  like association but informing the previous PC Distribution integration Similar to plugging in and out in a regular network

38 State variables and services
In a IBSS there is no auth. nor ass. Data service is allowed State 1: unauthenticated, unassociated Class 1 frames Successful authentication Deauthentication notification State 2: authenticated, unassociated Class 1 & 2 frames Deauthentication notification Successful authentication or reassociation Disassociation notification State 3: authenticated, associated A STA can be authenticated by several AP but associated only with one AP Class 1, 2 & 3 frames

39 BSSID y SSID BSSID (Basic Service Set Identity) SSID (Service Set ID)
BSS: MAC address of the AP Ad-Hoc: 46 bits random number SSID (Service Set ID) Known as the Network Name because it is basically the name that identifies the WLAN Lenght: 0~32 octets 0: it is the broadcast SSID Used to distinguish WLAN among them The access points and stations who want to connect to a single WLAN must use the same SSID

40 The Extended Service Set (ESS)
BSS AP WLAN LAN Distribution System (DS) Inter-acces point protocol (IAPP)

41 IAPP and the Task Group f
Scope of Project: to develop recommended practices for an Inter-Access Point Protocol (IAPP) which provides the necessary capabilities to achieve multi-vendor Access Point interoperability across a Distribution System supporting IEEE P Wireless LAN Links. Purpose of  Project: ... including the concepts of Access Points and Distribution Systems. Implementation of these concepts where purposely not defined by P As based systems have grown in popularity, this limitation has become an impediment to WLAN market growth. This project proposes to specify the necessary information that needs to be exchanged between Access Points to support the P DS functions. The information exchanges required will be specified for, one or more Distribution Systems; in a manner sufficient to enable the implementation of Distribution Systems containing Access Points from different vendors which adhere to the recommended practices Status The F Recommendation has been ratified and published in 2003. IEEE F was a Trial Use Recommended Practice. The IEEE 802 Executive Committee approved its withdrawal on February 03, 2006

42 Wireless Distribution System
IEEE , WDS means Multiple wireless “ports” inside the access-point, to wirelessly interconnect cells (access-points connecting to other access-points) pre-IEEE , did not support WDS: Three ports exist in one access-point (one Ethernet, and two wireless cells) One wireless backbone extension can be made (using two radio modules in the access-point) WDS allows: Extending the existing infrastructure with wireless backbone links Totally wireless system without any wired backbones, needed in locations where large areas are to be covered and wiring is not possible

43 WDS examples Bridging two wired networks
As a repeater to extend a network

44 Operational processes Traffic flow - WDS operation
AP-1000 or AP-500 Bridge learn table STA-2 AP-1000 or AP-500 2 Bridge learn table Avaya Wireless PC-Card STA-1 2 STA-2 Association table 2 Avaya Wireless PC-Card STA-2 STA-1 2 Association table Wireless Backbone STA-1 WDS Relay Packet for STA-2 ACK WDS Relay Packet for STA-2 ACK Packet for STA-2 ACK BSS-B STA-2 STA-1 BSS-A

45 Linksys Wireless-G Access Point

46 Linksys Wireless-G Access Point

47 Linksys Wireless-G Access Point

48 Linksys Wireless-G Access Point

49 Linksys Wireless-G Access Point

50 Linksys Wireless-G Access Point

51 Linksys Wireless-G Access Point

52 Linksys Wireless-G Access Point

53 Linksys Wireless-G Access Point

54 Linksys Wireless-G Access Point

55 Linksys Wireless-G Access Point

56 Redes Inalámbricas – Tema 2.C Wireless LANs: the IEEE 802.11 standards
The 802 wireless family IEEE The physical layer The MAC layer Quality of service: e MIMO: n Management tools

57 Limitations of the MAC standard for QoS
DCF (Distributed Coordination Function) Only support best-effort services No guarantee in bandwidth, packet delay and jitter Throughput degradation in the heavy load PCF (Point Coordination Function) Inefficient and complex central polling scheme Unpredictable beacon frame delay due to incompatible cooperation between CP and CFP modes Transmission time of the polled stations is unknown

58 Overview of e Task group e formed in Sep and Approved in July 2005 Current version: IEEE P802.11e/D13.0 Backwardly compatible with the DCF and PCF New QoS mechanism: HCF (Hybrid Coordination Function) Contention-based channel access EDCA (Enhanced Distributed Channel Access) was Enhanced Distributed Coordination Function (EDCF) Controlled channel access (includes polling) HCCA (HCF controlled channel access) The station that operates as the central coordinator for all other stations within the same QoS supporting BSS (QBSS) is called the hybrid coordinator (HC). The HC reside inside an AP A BSS that includes an e-compliant HC is referred to as a QBSS.

59 EDCA parameters for AC 4 access categories (AC),
AIFS[AC] = SIFS + AIFSN[AC] * aSlotTime, AIFSN[AC]  2.

60 EDCA and AC Mapping

61 HCF: Hybrid Coordination Function
During CFP Poll STAs and give a station the permission to access channel Starting time and maximum duration of each TXOP are specified by the HC During CP Can use the EDCA rules HC can issue polled TXOPs in the CP by sending CF-Poll after a PIFS idle period Controlled Contention Allows STAs to request the allocation of polled TXOPs STAs send resource request frames with the requested TC and TXOP duration HC sends an ACK for resource request to the STA

62 HCF superframes

63 Performance

64 QoS: 802.11e and WMM™ WMM (Wi-Fi Multimedia)
Prioritized QoS subset of e draft Widely accepted by e members Added to Wi-Fi certification in September 2004

65 WMM™ for Video Source: Wi-Fi Alliance

66 Redes Inalámbricas – Tema 2.C Wireless LANs: the IEEE 802.11 standards
The 802 wireless family IEEE The physical layer The MAC layer Quality of service: e MIMO: n Management tools Thanks to: Paul Young / Bernie Rasenberger

67 What is “Wireless N”? 802.11n is the long anticipated update to Wi-Fi standards. Ratified by IEEE in September 2009. “Pre-N” wireless devices were available prior to ratification (Draft N) with speeds of up to 300Mb/s and range of up to 300 metres (300x300). Increases channel utilisation through MAC aggregation (40MHz) and increased range & throughput through the use of MIMO (Multiple Input/Multiple Output) technology of 2+ antennas. Will co-exist with b/g networks, but can degrade them because of channel overlap caused by MAC aggregation. Same performance hit if you mix n clients with b clients, as you get with mixing g & b clients (OFDM).

68 What is “Wireless N”? 802.11n Release Date November 2009 Speed
300 Mbps Throughput 74 Mbps Frequency 2.4GHz &/or 5.0GHz Range (outdoor) 250 meters 802.11n’s improved technology 802.11n’s version of OFDM: a/g already uses OFDM (Orthogonal Frequency-Division Multiplexing) to achieve data rates of 54 Mbps n OFDM technology builds on a/g OFDM modulation by creating support for multiple channels (MIMO), allowing more bandwidth per channel, and higher code rates. This brings the maximum data rate of a single n OFDM channel to 65 Mbps. MIMO antenna systems: The n standard allows up to 4 MIMO transmit/receive antenna pairings n OFDM has a maximum data rate of 65 Mbps, multiplying that by the 4 MIMO antenna channels raises the data rate to 260 Mbps, which is a significant improvement when compared to 54 Mbps. 40 MHz channels: To further improve data rates, n allows the use of 40 MHz channels-twice the existing 20MHz channels used by a/b/g-which effectively doubles the data rate to over 500 Mbps. 40 MHz channel size is also the most controversial tenet of the new standard, having the potential to disrupt existing a/b/g networks due to co-channel interference. Aggregation: Aggregation is an important feature developed to overcome shortcomings of having to be backward compatible with a/b/g networks. It improves mixed-mode performance and efficiency by bundling several frames together that are destined for n devices, while still being able to transmit single data frames to legacy devices. RIFS (Reduced Inter-Frame Spacing): RIFS is a required n feature that also improves performance by reducing the amount of dead time required between OFDM transmissions. It should be noted that this feature is restricted to greenfield deployments.

69 Why is it so fast? Spatial multiplexing
With spatial multiplexing, the stream of data is split between 2 antennae and reassembled at the receiver. More data goes through in the same amount of time than when using a single antenna.

70 Why is it so fast? Support for 40Mhz Channels
So far each b/g channel only used 20MHz of the spectrum. With more spectrum available, more data can go through.

71 Wireless N is also more reliable
Through the use of Multipath we can achieve a more robust signal Antennas cleverly combine the same signal which has travelled through different paths. Even if the environment changes and some of the signal is obstructed, enough can still go through. This is how Wireless N achieves A ROBUST SIGNAL, less prone to interference and environmental changes. Resulting signal Transmitter Receiver Multiple copies of signal received Adjusted and combined signals

72 Deployment Considerations
802.11n can operate on 2.4 GHz or/and 5 GHz and is backward compatible with a/b/g. Access Points can be set to support 11n only. AP’s can be: single radio (2.4GHz only or 5GHz only) switchable dual radio (switchable between 2.4GHz and 5GHz) concurrent dual radio (operates 2.4GHz and 5GHz at the same time)

73 Deployment Considerations
When introducing n into existing a/b/g WLANs both bands (2.4GHZ and 5GHz) can have n enabled. In case of dense AP architecture channel bonding for 2.4GHz should be disabled (set to 20MHz). Or if there are other 2.4GHz networks in the area – disable channel bonding for 2.4GHz. 802.11n can be offered to throughput-critical clients only which support 11n: 5GHz band can be set as “11n only”. Leaving 2.4GHz for the rest of the clients which will not interfere with the critical data (802.11b/g/n). dual-radio n AP 2.4GHz 802.11b/g/n 5GHz 802.11n only High Speed Wi-Fi Legacy mixed Wi-Fi 802.11n client

74 The ‘Sting’ Increased channel spectrum from 22Mhz to 40Mhz, using MAC aggregation techniques; Consumes 2 of 3 non overlapping 2.4Ghz channels; Not an issue in “pure N” networks, but will cause issues in hybrid networks; Uses OFDM, so if b clients on network performance degrades for all users.

75 Redes Inalámbricas – Tema 2.C Wireless LANs: the IEEE 802.11 standards
The 802 wireless family IEEE The physical layer The MAC layer Quality of service: e MIMO: n Management tools

76 Wireshark / Ethereal Wireshark is the world's foremost network protocol analyzer, and is the de facto (and often de jure) standard across many industries and educational institutions. Wireshark development thrives thanks to the contributions of networking experts across the globe. It is the continuation of a project that started in 1998.

77 Wireshark Features Deep inspection of hundreds of protocols, with more being added all the time Live capture and offline analysis Standard three-pane packet browser Multi-platform: Runs on Windows, Linux, OS X, Solaris, FreeBSD, NetBSD, and many others Captured network data can be browsed via a GUI, or via the TTY-mode TShark utility Rich VoIP analysis Read/write many different capture file formats: Capture files compressed with gzip can be decompressed on the fly Live data can be read from Ethernet, IEEE , PPP/HDLC, ATM, Bluetooth, USB, Token Ring, Frame Relay, FDDI, and others Decryption support for many protocols, including IPsec, ISAKMP, Kerberos, SNMPv3, SSL/TLS, WEP, and WPA/WPA2 Output can be exported to XML, PostScript®, CSV, or plain text

78 Wireshark / Ethereal

79 Kismet Kismet is an layer2 wireless network detector, sniffer, and intrusion detection system. Kismet will work with any wireless card which supports raw monitoring (rfmon) mode, and can sniff b, a, and g traffic. Kismet identifies networks by passively collecting packets and detecting standard named networks, detecting (and given time, decloaking) hidden networks, and infering the presence of nonbeaconing networks via data traffic. Some of the features Ethereal/Tcpdump compatible data logging Built-in channel hopping and multicard split channel hopping Hidden network SSID decloaking Graphical mapping of networks Manufacturer and model identification of access points and clients Detection of known default access point configurations Runtime decoding of WEP packets for known networks Over 20 supported card types

80 gKismet

81 Network Stumbler Allows to save and export data in several different formats Supports GPS and the ability to store GPS information in conjunction with other data

82 Network Stumbler The graphical interface used is very intuitive and allows various types of analysis in a simple and direct form

83 Network Stumbler


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