Lecture1-BasicSecurityReview

Lecture1-BasicSecurityReview - 802.11 Basic Security Review...

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802.11 Basic Security Review CIT 456 Spring 2009
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Scanning Passive Listening on each channel for a specific time Station listens until it hears a beacon listing SSID of one it wants to join If multiple AP’s, joins AP with Strongest signal Lowest Bit Error Rate Continues after association Saves time if disconnected (disassociated) » Keeps list of available AP’s » Can quickly locate the best
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Passive Scanning (Cont.) Also used to Roam Locate next best AP Therefore, overlap cells 20-30% Creates “seamless” roaming NOTE!! Roaming is NOT specified in 802.11
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Active Scanning Station sends a Probe Request Frame Actively seeking to join Contains SSID of desired network OR Contains Broadcast SSID Only AP’s servicing that SSID will respond Send back Probe RESPONSE Frame Similar to Beacon Frames EXCEPT » No time stamp » No TIM
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Other Scanning Notes Active and Passive can happen on the same network at the same time “Closed System” Removes SSID from Beacons Hide SSID from Scanning Utilities Can still snag SSID from Probe Response Frames
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Authentication Methods Open System Authentication Simple 2 step process described previously Only requires correct SSID
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This note was uploaded on 02/29/2012 for the course CNIT 456 taught by Professor A.h.smith during the Spring '12 term at Purdue.

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Lecture1-BasicSecurityReview - 802.11 Basic Security Review...

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