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Transcript of 1 Architecture and Techniques for Diagnosing Faults in IEEE 802.11 Infrastructure Networks Atul...
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Architecture and Techniques for Diagnosing Faults in IEEE 802.11 Infrastructure NetworksAtul Adya, Victor Bahl, Ranveer Chandra, Lili Qiu
Microsoft Research
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Wireless Network WoesHow many times have you heard users say:My machine says: wireless connection unavailableWhy cant my machine authenticate?My performance on wireless really sucksIT Dept: Several hundred complaints per monthYou may have heard network admins say:I wonder if some one has sneakily installed an unauthorized access pointDo we have complete coverage in all the buildings?
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Enterprise Wireless Problems
Main problems observed by IT department:Connectivity: RF HolesAuthentication: 802.1x protocol issuesPerformance: Unexplained delaysSecurity: Rogue APs
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Existing ProductsProvide management/diagnostic functionsE.g., AirWave, CAs NSM, Air Defense, Air Magnet
Insufficient functionality:No support for disconnected clientsWeak root-cause analysis (raw data, mostly)Diagnosis only from the AP perspectiveSometimes need expensive sensor deployment
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Our ContributionsFlexible client-based framework for detection and diagnosis of wireless faults
Client Conduit: communication for disconnected clients via nearby connected clients
Diagnostic mechanismsApproximate location of disconnected clientsRogue AP detectionPerformance problem analysis
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Talk OutlineDiagnostics architecture and implementationClient Conduit: diagnosing disconnected clientsDiagnostic mechanismsLocating disconnected clientsDetecting unauthorized APsAnalyzing performance problemsSummary and Future Work
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AssumptionsCan install diagnostic software on clientsAPs are typically closed platformsCan provide improved diagnosis with modified APsNearby clients available for fault diagnosisAt least 13 active clients on our floor (approx. 2500 sq. feet)Network admins maintain AP Location Database
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Client-Centric ArchitectureDiagnostic AP Module (DAP)RADIUSKerberosLegacy APDisconnected ClientClientConduitAuthentication/User InfoDiagnostic Client Module (DC)DiagnosticServer (DS)
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Diagnostic Architecture Properties
Exploits client-view of network (not just APs)
Supports proactive and reactive mechanisms
Scalable
Secure
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Client ImplementationPrototype system on Windows
Native WiFi: Extensibility framework for 802.11 [Microsoft Networking 2003]
Daemon: most of functionality and main control flow
IM driver: limited changesPacket capture & monitoring
Native WiFi NIC
NDIS
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Talk OutlineDiagnostics architecture and implementationClient Conduit: diagnosing disconnected clientsDiagnostic mechanismsLocating disconnected clientsDetecting unauthorized APsAnalyzing performance problemsSummary and Future Work
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Cause of Disconnection
Lack of coverageIn an RF HoleJust outside AP rangeAuthentication issues, e.g., stale certificatesProtocol problems, e.g., no DHCP address
Can we communicate via nearby connected clients?
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Communication via Nearby ClientsPossible (unsatisfactory) solutions:Multiple radios: extra radio for diagnosticsMultiNet [InfoCom04]: Multiplex Happy between Infrastructure/Adhoc modesPenalizing normal case behavior for rare scenarioConnected Client Happy (Infrastructure)Disconnected ClientGrumpyAccess PointCannot be on 2 networks. Packet dropped!SOSAdhoc Mode
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Our Solution: Client Conduit Stops beaconingConnected Client HappyDisconnectedClient GrumpyAccess PointDisconnected station detected Becomes an Access Point(Starts beaconing)SOS (Beacon)SOS Ack(Probe Req)Ad hoc network via MultiNetHelp disconnected wireless clients with:Online diagnosisCertificate bootstrapping DisconnectedClient Not-so-Grumpy
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Client Conduit Features
Incurs no extra overhead for connected clientsUse existing 802.11 messages: beacons & probes
Works with legacy APs
Includes security mechanisms to avoid abuses
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Client Conduit PerformanceTime for Grumpy to get connected < 7 secondsReduced time can enable transparent recoveryBandwidth available for diagnosis > 400 Kbps (when Happy donates only 20% of time)
Chart1
0.174894462.183125140.13889390.118577080.3901191.836074881.86099
0.17500.1250.10.39011901.86099
6.7 seconds
2.7 seconds
Set channel
Become AP
Set SSID
Set Beacon Period
Get Ack
Become Station
Adhoc-mode association
Time (seconds)
Conduit
ORIGINAL VALUES
User time
Actionwhen finished (ms)User time (ms)Kernel time (ms)With PollUser time with polling (ms)Time (seconds)Actionwhen finished (ms)User time (ms)Kernel time (ms)With PollUser time with polling (ms)
Set channel174.89446174.89446175176.6462666667176.64626666670.174894460.175Set channel174.89446174.89446175176.6462666667176.6462666667
Become AP1358.01962183.12514998.4381106.1061929.45983333332.183125140Detect nearby client190.5097615.61530192.23315.5867333333
Sleep 1 second2358.0196100010002106.1061100010Become AP1358.01961167.50984998.4381106.1061913.8731
Set SSID2496.9135138.89391252291.3894833333185.28338333330.13889390.125Sleep 1 second2358.0196100010002106.10611000
Set Beacon Period2615.49058118.577081002397.72515106.33566666670.118577080.1Set SSID2496.9135138.89391252291.3894833333185.2833833333
Get Ack3005.60958390.119390.1198816.31566418.590450.3901190.390119Set Beacon Period2615.49058118.577081002397.72515106.3356666667
Become Station3841.684461836.07488998.4389918.381102.06441.836074880Get Ack3005.60958390.119390.1198816.31566418.59045
Sleep 1 second10001000100010Become STA3841.68446836.07488998.4389918.381102.0644
Adhoc-mode association1860.991860.991860.991.860991.86099Sleep 1 second100010001000
Adhoc-mode association1860.991860.991860.99
8702.674468.702674462.651109
No mode changes
ASSOCIATION_INFO0ms,Total=
RCHECK_ADAPTER0ms,Total=0-5
RGET_CAPTURED_PACKETS0ms,Total=0-319
RGET_GENERIC_INFOS0ms,Total=0-233
RQUERY_ADAPTER_LIST0ms,Total=0-6
RRECEIVE_UPCALL0ms,Total=0-314
R8021X_STATE31.25ms,Total=0-10
WBEACON_PERIOD100ms,Total=125-20
WCAPTURE_FILTER0ms,Total=100-5
WCURRENT_CHANNEL175ms,Total=0-15
WCURRENT_OPERATION_MODE998.438ms,Total=350-10
WDESIRED_SSID125ms,Total=1996.875-10
WDIAGNOSTIC_MSG0ms,Total=125-5
WPROMISCUOUS_MODE0ms,Total=0-5
WSET_SPECIAL_EVENT0ms,Total=0-5
W0-5
Conduit
174.894461183.125141000138.8939118.57708390.119836.0748810001860.99
175998.4381000125100390.119998.43810001860.99
176.6462666667929.45983333331000185.2833833333106.33566666676418.590451102.064410001860.99
Set channel
Become AP
Sleep 1 second
Set SSID
Set Beacon Period
Get Ack
Become STA
Sleep 1 second
Adhoc-mode association
Time (msec)
Channels
AP ChannelFor 5 scans
1123
21234
3123456
4123456
51234567
6345678
7345678910
84567891011
9567891011
10678910
117891011
AP channel (for 1 scan)
113
2123
3123456
412346
52345
645678
74678
8458911
967891011
107810
1181011
Channels
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
00000000000000
Detected in 1 and 5 sec runsDetected only in 5 sec run
Channel on which AP beacons
Channel on which beacons are decoded correctly
Motivation
000000
000000
000000
000000
000000
000000
000000
000000
000000
000000
000000
Channel on which AP beacons
Channel on which beacons are decoded correctly
Promiscuous-CPU
MonthNo. of Wireless-related problems
1675
2525
3600
4515
5515
6675
Promiscuous-CPU
0
0
0
0
0
0
Month
No. of wireless-related problems
Arch
Promiscuous modeNon-promiscuous mode
Time (secs)CPUTime (secs)CPU
0-6.1800-6.20
0.53-5.655.780.53-5.670
1.05-5.138.991.05-5.150
1.56-4.6201.56-4.640
2.08-4.18.992.08-4.120
2.59-3.595.952.59-3.610
3.11-3.072.923.11-3.090
3.62-2.5603.62-2.580
4.14-2.042.924.14-2.060
4.65-1.532.924.65-1.550
5.17-1.012.925.17-1.030
5.68-0.52.925.68-0.520
6.18006.200
6.680.506.710.510
7.21.025.957.211.010
7.711.532.927.731.530
8.212.036.148.222.020
8.712.536.148.742.540
9.223.042.929.263.060
9.743.562.929.773.570
10.254.078.9910.294.095.95
10.754.573.0210.84.60
11.275.09011.325.120
11.775.593.0211.825.620
12.276.093.0212.316.110
12.776.593.0212.816.610
13.277.096.1413.317.110
13.787.65.9513.837.630
14.38.125.9514.348.140
14.818.635.9514.868.660
15.339.15015.379.170
15.839.653.0215.899.692.92
16.3410.16016.3910.190
16.8410.666.1416.8910.693.02
17.3411.163.0217.411.28.99
17.8611.685.9517.911.70
18.3712.195.9518.412.20
18.8712.696.1418.912.79.27
19.3813.25.9519.4113.210
19.913.725.9519.9113.710
20.4114.235.9520.4314.230
20.9314.75020.9514.750
21.4515.272.9221.4615.260
21.9415.7615.5321.9615.760
22.4416.26022.4616.260
22.9416.76022.9616.760
23.4617.282.9223.4717.270
23.9717.792.9223.9717.770
24.4918.312.9224.4918.290
2518.828.992518.80
25.5219.342.9225.5219.320
26.0519.872.8326.0219.820
26.5520.373.0226.5220.320
27.0620.88027.0220.823.02
27.5821.45.9527.5221.323.02
28.0921.915.9528.0221.820
28.5922.416.1428.5322.330
29.0922.913.0229.0522.850
29.6223.44029.5623.362.92
30.1223.943.0230.0723.870
30.6224.443.0230.5924.392.92
31.1424.962.9231.0924.893.02
31.6525.47031.5925.390
32.1725.99032.0925.890
32.6826.5032.5926.390
33.227.028.9933.126.92.92
33.7127.53033.6227.420
34.2328.052.9234.1327.930
34.7428.568.9934.6328.430
35.2629.08035.1328.930
35.7729.592.9235.6329.430
36.2930.112.9236.1329.930
36.7930.619.2736.6330.430
37.2931.113.0237.1530.950
37.7831.6037.6631.460
38.332.122.9238.1831.980
38.8232.642.9238.6932.490
39.3333.152.9239.2133.010
39.8533.672.9239.7233.525.95
40.3634.185.9540.2434.040
40.8834.72.9240.7534.550
41.3935.2112.0241.2735.070
41.9135.735.9541.7735.570
42.4236.242.9242.2736.070
42.9436.768.9942.7636.563.02
43.4437.266.1443.2837.082.92
43.9537.772.9243.7937.590
44.4538.27044.3138.112.92
44.9738.798.9944.8238.620
45.4839.35.9545.3239.120
45.9839.89.2745.8439.640
46.5140.332.8346.3540.150
47.0240.842.9246.8740.670
47.5441.368.9947.3841.180
48.0641.882.9247.8841.680
48.5742.392.9248.3842.180
49.0942.912.9248.8842.680
49.643.425.9549.443.20
50.143.92049.9143.710
50.6244.4412.0250.4344.230
51.1344.952.9250.9444.740
51.6545.472.9251.4645.260
52.1445.963.0251.9745.770
52.6646.48052.4946.290
53.1646.986.145346.80
53.6647.483.0253.5247.320
54.1747.99054.0347.830
54.6948.512.9254.5348.330
55.1949.016.1455.0348.830
55.749.528.9955.5349.330
56.2250.045.9556.0349.830
56.7350.552.9256.5550.350
57.2551.075.9557.0650.860
57.7551.57057.5851.380
58.2552.07058.0951.890
58.7552.57058.6152.410
59.2553.076.1459.1252.920
59.7653.585.9559.6453.440
60.2654.086.1460.1553.950
60.7754.595.9560.6554.453.02
61.2955.11061.1554.950
61.7955.613.0261.6655.460
62.2956.113.0262.1855.980
62.7956.61062.6856.480
63.2957.11063.1856.980
63.7957.613.0263.6857.480
64.358.122.9264.1957.990
64.858.62064.7158.510
65.359.123.0265.2159.010
65.859.623.0265.7159.510
66.360.12066.2260.020
66.8160.638.9966.7260.520
67.3361.155.9567.2261.020
67.8461.668.9967.7261.523.02
68.3662.18068.2362.030
68.8862.72.9268.7562.550
69.3963.215.9569.2763.070
69.9163.73069.7863.585.95
70.4264.242.9270.2864.083.02
70.9464.76070.864.60
71.4565.27071.2965.090
71.9765.79071.7965.590
72.4866.32.9272.2966.090
72.9866.83.0272.8166.610
73.567.322.9273.3167.110
74.0167.832.9273.8267.620
74.5368.35074.3468.140
Arch
00
00
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Promiscuous mode
Normal mode
Time (secs)
CPU Usage
Location-1
Real dataNo filtered data
040733.9775390625040733.9775390625
119304.88574218751144708.3427734375
227295.5976562522457312.80859375
335226.10742187533456617.267578125
445206.61523437544456721.7275390625
556357.235351562555467926.296875
668308.045898437566467230.859375
779398.96289062577467235.421875
887279.672851562588467439.986328125
9963310.29101562599467444.55078125
11082011.091796875110467649.1171875
12172511.7998046875121467753.6845703125
13241312.203125132467758.251953125
14363012.818359375143467762.8193359375
18751013.31640625154467767.38671875
19851713.8212890625165467771.9541015625
22041314.224609375176467776.521484375
23140414.619140625187467681.087890625
24240415.013671875198467785.6552734375
25351915.5205078125209467590.220703125
26441415.9248046875220467594.7861328125
27552016.4326171875231467699.3525390625
29752616.94628906252424676103.9189453125
30851917.4531252534675108.484375
31951117.95214843752644676113.05078125
33040418.34667968752754677117.6181640625
34141418.75097656252864676122.1845703125
37341119.152343752974790126.8623046875
38452019.660156253084783131.533203125
41741420.0644531253194783136.2041015625
43962820.6777343753304782140.8740234375
45052921.19433593753414783145.544921875
48340421.58886718753514783150.2158203125
51652022.09667968753624783154.88671875
52740422.49121093753734783159.5576171875
53862823.10449218753844783164.228515625
54941323.50781253954784168.900390625
56041323.91113281254064782173.5703125
57152324.4218754174782178.240234375
58251824.9277343754284782182.91015625
60341325.33105468754394784187.58203125
61441325.7343754504887192.3544921875
62541426.1386718754614982197.2197265625
63641326.54199218754724975202.078125
64763327.160156254834975206.9365234375
65852327.67089843754944974211.7939453125
66974428.39746093755054975216.65234375
68052328.9082031255164974221.509765625
69152329.41894531255274974226.3671875
71361730.0214843755384975231.2255859375
72440330.41503906255494975236.083984375
73561431.01464843755604975240.9423828125
74651331.5156255714974245.7998046875
75752332.02636718755824975250.658203125
76852332.5371093755934975255.5166015625
77941332.94042968756034975260.375
79051333.441406256144975265.2333984375
80151433.9433593756254976270.0927734375
81263134.55957031256364975274.951171875
82341334.9628906256474975279.8095703125
84541335.36621093756584975284.66796875
86751935.8730468756695086289.634765625
87852136.38183593756805080294.595703125
88941336.785156256915080299.556640625
90062837.39843757025080304.517578125
91173338.11425781257135081309.4794921875
92241338.5175781257245080314.4404296875
93341638.9238281257355182319.5009765625
95552039.4316406257465176324.5556640625
96773440.14843757575177329.611328125
97841640.55468757685177334.6669921875
98952441.066406257795177339.72265625
100041341.46972656257905178344.779296875
102252041.97753906258015177349.8349609375
103362742.589843758125178354.8916015625
104452543.10253906258235178359.9482421875
105652343.613281258345177365.00390625
106741744.02050781258455177370.0595703125
107841444.42480468758565177375.115234375
108951944.9316406258675176380.169921875
110162945.54589843758785177385.2255859375
111241345.949218758895177390.28125
113541646.355468759005175395.3349609375
114652446.86718759115176400.3896484375
116841647.27343759225176405.4443359375
117952347.78417968759335176410.4990234375
119052148.292968759445176415.5537109375
120152348.80371093759555176420.6083984375
121241349.207031259675177425.6640625
122352249.7167968759785175430.7177734375
125652450.2285156259895176435.7724609375
126741350.631835937510005175440.826171875
127841351.0351562510115176445.880859375
128962951.649414062510225176450.935546875
130083252.461914062510335177455.9912109375
131163053.077148437510445288461.1552734375
132241353.4804687510565283466.314453125
134341453.88476562510675284471.474609375
136552254.3945312510785283476.6337890625
137641454.79882812510895281481.791015625
139841655.20507812511015284486.951171875
140941455.60937511125282492.109375
146452356.120117187511235283497.2685546875
148641656.526367187511355282502.4267578125
151962957.14062511465284507.5869140625
153041657.54687511575284512.7470703125
157352458.0585937511685283517.90625
158484458.882812511795283523.0654296875
159562659.49414062511905283528.224609375
160652360.004882812512015282533.3828125
162841460.409179687512125283538.5419921875
163952060.916992187512235282543.7001953125
165072961.6289062512345283548.859375
166162962.243164062512455283554.0185546875
167241362.64648437512565285559.1796875
168351963.153320312512675283564.3388671875
169452363.664062512785281569.49609375
170541464.06835937512895283574.6552734375
171641464.4726562513005282579.8134765625
172741364.875976562513115285584.974609375
174941365.27929687513225283590.1337890625
176051965.786132812513325283595.29296875
177141366.18945312513435282600.451171875
179341466.5937513545281605.6083984375
181551967.100585937513655281610.765625
182652067.608398437513765282615.923828125
183741368.0117187513875282621.08203125
184852068.5195312513985283626.2412109375
186941768.926757812514095284631.4013671875
188041369.33007812514205284636.5615234375
190241369.733398437514315284641.7216796875
191341370.1367187514425283646.880859375
192441370.540039062514535283652.0400390625
193541370.94335937514645282657.1982421875
194652171.452148437514755283662.357421875
197941371.8554687514865282667.515625
199041372.258789062514975281672.6728515625
200152072.766601562515085282677.8310546875
201262673.377929687515195283682.990234375
202351973.88476562515305283688.1494140625
203462874.49804687515415284693.3095703125
204562675.10937515525282698.4677734375
205641375.512695312515625281703.625
206741375.91601562515735283708.7841796875
207873576.633789062515845281713.94140625
208941377.03710937515955281719.0986328125
211141477.4414062516065281724.255859375
213252277.95117187516175280729.412109375
214452278.460937516285281734.5693359375
215541378.864257812516395280739.7255859375
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No Filters at DC
Filtered at DC
Time (seconds)
Cummulative no. of KBytes sent
Location-2
MedianMinMaxMedian -minMax - Median
No Error0007.3810028149.748229672710.525641312812.274749197512.28342272519.7482296727012.28342272519.74822967272.5351930523
E(1)103.0488.034210082510.525641312810.798075537312.274749197512.283422725110.5256413128012.283422725110.52564131281.7577814123
E(2)208.03421008259.748229672711.901763311712.274749197512.274749197512.283422725111.9017633117012.283422725111.90176331170.3816594134
E(1,2)303.0489.56899547819.611252204610.798075537311.831827397517.28654806599.6112522046017.28654806599.61125220467.6752958613
E(3)407.461146119.43545614139.74463252839.748229672710.525641312812.27474919759.7446325283012.27474919759.74463252832.5301166693
E(1,3)53.048119387.461146118.28519353669.43545614139.744632528311.938076834512.27474919759.43545614133.0481193812.27474919756.38733676132.8392930562
E(2,3)603.93256355029.748229672711.901763311712.136711647412.274749197512.283422725111.9017633117012.283422725111.90176331170.3816594134
E(1,2,3)72.81939980243.048119383.93256355027.4611461112.136711647416.93270108717.11584957667.461146112.819399802417.11584957664.64174630769.6547034666
Location-2
02.53519305239.7482296727
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00.381659413411.9017633117
07.67529586139.6112522046
02.53011666939.7446325283
02.83929305626.3873367613
00.381659413411.9017633117
09.65470346664.6417463076
Median Location Error (metres)
Idletimes
MedianMinMaxMedian -minMax - Median
No Error0007.3810028149.748229672710.525641312812.274749197512.28342272519.7482296727012.28342272519.74822967272.5351930523
E(1)16.095880628.03421008259.287677220110.525641312810.798075537312.274749197517.286548065910.52564131286.0958806217.28654806594.42976069286.7609067531
E(2)2003.181230629.56899547819.748229672710.798075537317.28654806599.5689954781017.28654806599.56899547817.7175525878
E(1,2)33.181230626.095880628.78269946749.28767722019.568995478110.798075537333.53014225769.28767722013.1812306233.53014225766.106446600124.2424650375
E(3)4009.61125220469.74463252839.748229672710.525641312817.39661083639.7446325283017.39661083639.74463252837.6519783081
E(1,3)53.93256355026.096119387.461146117.800091786912.283422725117.396610836325.28484077897.80009178693.932563550225.28484077893.867528236717.484748992
E(2,3)605.71646294587.4611461111.733814059511.938076834513.423900000215.011933779711.7338140595015.011933779711.73381405953.2781197202
E(1,2,3)73.93256355026.096119387.18859282487.461146117.80009178699.435456141332.9723493457.461146113.932563550232.9723493453.528582559825.511203235
Idletimes
02.53519305239.7482296727
06.76090675314.4297606928
07.71755258789.5689954781
024.24246503756.1064466001
07.65197830819.7446325283
017.4847489923.8675282367
03.278119720211.7338140595
025.5112032353.5285825598
Median Location Error (metres)
TimeReal TimeAvg Idle PeriodAvg Max Idle PeriodTotal Idle PeriodsNum Samples
00.000099.2593223.1111279
10.083376.2286202.0000359
20.166780.8182234.7778339
30.250066.6250198.7778409
40.333347.9592171.7500498
50.4167119.3500238.6250208
60.500083.4688230.6667329
70.583357.4390207.2500418
80.666769.7632205.4444389
90.750078.3529205.3333349
100.833386.3226218.7778319
110.916799.1111237.6667279
121.000092.1724220.1111299
131.083389.1667209.3333309
141.166792.3793224.4444299
151.250064.8537207.2222419
161.333381.0303198.8889339
171.4167134.4500248.1111209
181.5000122.0909239.7778229
191.583378.5294208.5556349
201.666757.2609185.4444469
211.7500127.8571239.6667219
221.833383.6563205.6667329
231.9167103.1154220.3333269
242.0000122.0909240.4444229
252.083355.2708202.0000489
262.166766.3750231.5556409
272.250078.5294213.7778349
282.333343.1967182.4444619
292.416742.4194221.2222629
302.500092.3448222.3333299
312.583381.0909218.2222339
322.666771.5135192.7778379
332.750086.2258207.8889319
342.833379.5667179.4444309
352.916799.1667235.0000248
363.000099.2500215.3750248
373.083379.1724193.6250298
383.1667103.4348238.7500238
393.250099.3333223.3333279
403.333378.5000200.0000349
413.416772.0606183.3333339
423.5000103.6522233.1250238
433.583368.4359202.5556399
443.666771.5135199.8889379
453.750078.4118210.1111349
463.833368.2051211.1111399
473.916792.2069227.1111299
484.000095.5000227.6667289
494.083365.0000205.8889419
504.1667128.0000247.1111219
514.250086.1290214.7778319
524.333389.0667199.5556309
534.4167134.4000249.5556209
544.5000111.8333238.2222249
554.583372.1892203.4444379
564.666783.0000199.0000329
574.750092.2414234.6667299
584.833378.5000213.4444349
594.9167134.4500249.5556209
605.000086.3226228.8889319
615.083370.2105196.0000389
625.166786.2258234.1111319
635.250063.3810195.8889429
645.333355.3333179.4444489
655.4167103.1154240.5556269
665.500089.2333238.1111309
675.583354.1020204.8889499
685.666758.4889174.7778459
695.750072.0000216.2222379
705.833376.2857200.7778359
715.916786.1290246.3333319
726.0000107.2800237.7778259
736.083380.9697212.3333339
746.166789.0667230.4444309
756.250089.0333227.7778309
766.333364.8780182.4444419
776.4167107.2800231.5556259
786.500086.2258216.4444319
796.583374.1389196.4444369
806.666766.2250176.3333409
816.750086.3226221.4444319
826.833381.9310202.0000298
836.916765.5278202.1250368
847.0000104.3000235.0000207
857.083399.3333208.7143217
867.1667122.7059243.2857177
877.250079.8846208.8571267
887.333362.2727172.5714337
897.4167116.0000242.8571187
907.500063.9189208.0000378
917.583362.8485194.2857337
927.666788.8500194.1667206
937.750084.7143219.1667216
947.833381.9655180.0000298
957.9167115.9444237.7143187
968.000059.0000167.1250408
978.0833104.3000214.8571207
988.1667103.4348236.5000238
998.250074.1250202.3750328
1008.333376.6774179.7500318
1018.4167119.3500239.5000208
1028.500083.1600223.4286257
1038.583364.6563172.5714327
1048.666779.6538189.5714267
1058.750099.2857222.8571217
1068.833368.4231178.0000266
1078.916784.9524197.6667216
1089.000089.3000209.3333206
1099.083342.7317149.6667416
1109.166755.1250204.3333326
1119.250061.2069201.8333296
1129.333374.2500146.2000205
1139.416759.1000187.0000306
1149.500048.8889147.6667366
1159.583368.4615169.3333266
1169.666765.3333167.6667276
1179.750094.0000208.3333196
1189.833377.5217154.3333236
1199.916781.0000211.1667226
12010.000094.0000208.6667196
12110.083384.9524182.1667216
12210.166781.0000202.8333226
12310.250089.2500209.1667206
12410.333347.6216157.3333376
12510.416728.0000159.6667616
12610.500077.3913210.0000236
12710.583381.0455181.8333226
12810.666763.0000167.8333286
12910.750057.0645182.5000316
13010.833358.8667172.8333306
13110.916756.9677161.8333316
13211.000063.3214176.8333286
13311.083355.3438164.8333326
13411.166746.1316185.1667386
13511.250085.0000209.8333216
13611.333370.6667144.6000215
13711.416778.1053186.6000195
13811.500089.2500212.3333206
13911.583368.4231175.5000266
14011.666753.2121152.0000336
14111.750056.9032205.6667316
14211.833357.0323172.0000316
14311.916794.0000204.1667196
14412.000059.4828192.1667296
14512.083367.3636159.0000225
14612.166747.3871180.2000315
14712.250036.8205181.2000395
14812.333349.1111156.6667366
14912.416799.2667215.4000155
15012.500043.8000195.0000406
15112.583324.7206141.1667686
15212.666733.8235130.1667516
15312.750036.9787164.8333476
15412.833320.7761149.0000675
15512.916746.2895197.8333386
15613.000071.1200173.6667256
15713.083360.4828161.6667296
15813.166770.6667192.4000215
15913.250078.2105197.2000195
16013.333352.7500153.6000285
16113.416764.2609199.4000235
16213.500067.2727173.4000225
16313.583349.1250141.2500244
16413.666745.5000145.6000325
16513.750074.2500179.4000205
16613.833360.6667150.2000245
16713.916786.8235205.0000175
16814.000073.4500213.2000205
16914.083343.0000156.8000345
17014.166799.3333216.0000155
17114.250067.2273208.8000225
17214.333344.2424159.8000335
17314.416754.2963179.6000275
17414.5000106.5000202.4000145
17514.583350.6207139.0000295
17614.666777.5789162.4000195
17714.750067.2273184.0000225
17814.833393.0625183.8000165
17914.9167124.2500240.8000125
18015.0000124.4167244.2000125
18115.083352.6071143.8000285
18215.166777.9474187.6000195
18315.250074.1500166.4000205
18415.333364.1739134.0000235
18515.416799.1333204.2000155
18615.500070.5238211.4000215
18715.583370.6667181.6000215
18815.666753.0909193.5000224
18915.750099.2500213.7500124
19015.833343.3333140.0000274
19115.916747.1290188.8000315
19216.000087.4118198.6000175
19316.083363.3214165.0000286
19416.166756.9032159.0000316
19516.250040.6279163.1667436
19616.333352.0000147.1667346
19716.416777.3043186.0000236
19816.500051.9118174.5000346
19916.583351.9706135.5000346
20016.666752.9091156.1667336
20116.750065.5926195.1667276
20216.833347.5946151.3333376
20316.916747.7027159.6667376
20417.000059.1333170.1667306
20517.083334.0000143.6667516
20617.166742.7073152.6667416
20717.250052.9697196.0000336
20817.333342.5610123.3333416
20917.416759.0000181.5000306
21017.500051.7941161.0000346
21117.583343.8000164.1667406
21217.666735.0000146.5000486
21317.750052.0714167.2000285
21417.833341.7143152.6667426
21517.916755.2188185.1667326
21618.000056.7097182.8333316
21718.083336.9574143.8333476
21818.166743.0882153.0000345
21918.250042.9118140.4000345
22018.333323.8500137.0000605
22118.416732.0444142.2000455
22218.500035.6122173.5000496
22318.583332.5660146.5000536
22418.666749.6571181.0000356
22518.750035.6458154.3333486
22618.833334.0196166.6667516
22718.916720.0241128.3333836
22819.000020.3205147.6667786
22919.083318.2432118.0000745
23019.166721.7126141.2857877
23119.250029.8276132.8333586
23219.333330.4375134.2857647
23319.416733.5714160.2000425
23419.500049.8621168.8000295
23519.583352.2051156.0000397
23619.666743.5000145.1667406
23719.750057.0968163.1667316
23819.833360.6471175.4286347
23919.916764.7500198.8571327
24020.000042.5833165.0000487
24120.083337.4630159.5714547
24220.166753.6591179.7500448
24320.250062.6061192.1429337
24420.333332.5429160.3750708
24520.416743.8462186.8750528
24620.500033.6029178.3750688
24720.583337.9057122.4286537
24820.666736.4000172.0000557
24920.750041.9091185.2500558
25020.833329.7273136.6250778
25120.916733.2754169.1250698
25221.000038.0820164.7500618
25321.083336.0000169.5000648
25421.166740.7143169.3750568
25521.250035.1719154.3750648
25621.333350.3913174.3750468
25721.416735.2923193.0000658
25821.500023.8556145.6250908
25921.583325.8851135.2500878
26021.666735.9444161.0000547
26121.750036.3617173.6667476
26221.833342.5854188.5000416
26321.916751.7353198.5000346
26422.000047.1081201.3333376
26522.083361.1034186.5000296
26622.166784.7619214.5000216
26722.250047.0811183.8333376
26822.333374.2500190.6667246
26922.416760.8621200.5000296
27022.500030.7857122.5000566
27122.583350.0571216.6667356
27222.666748.4722174.6667366
27322.750052.5000204.0000285
27422.833393.0625204.4000165
27522.916774.1389215.1111369
27623.000092.1034216.8889299
27723.083363.3095182.7778429
27823.166795.6429218.1111289
27923.250071.9189194.8889379
28023.333363.2381150.7778429
28123.4167128.0000226.2222219
28223.500066.5750182.1111409
28323.583364.9512185.2222419
28423.666752.5400165.4444509
28523.750099.1481217.5556279
28623.833374.1111200.1111369
28723.9167111.7917228.5556249
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Avg Max Idle Period
Time of day (hours)
Max idle period (seconds) every 5 minutes
-
Talk OutlineDiagnostics architecture and implementationClient Conduit: diagnosing disconnected clientsDiagnostic mechanismsLocating disconnected clientsDetecting unauthorized APsAnalyzing performance problemsSummary and Future Work
-
Locating Disconnected ClientsGoal: Approximately locate to determine RF HolesSolution: Use nearby connected clients
Grumpy starts beaconingNearby clients report signal strength to serverDiagnostic server uses RADAR [InfoCom00] twiceLocates connected clientsLocates Grumpy with clients as anchor pointsLocation error: 10 15 meters
-
Talk OutlineDiagnostics architecture and implementationClient Conduit: diagnosing disconnected clientsDiagnostic mechanismsLocating disconnected clientsDetecting unauthorized APsAnalyzing performance problemsSummary and Future Work
-
Rogue AP ProblemsWhy problematic?Allow network access to unauthorized usersHurt performance: interfere with existing APs
Detection goals:Common case: mistakes by employeesDetect unauthorized IEEE 802.11 APsNot considering non-compliant APs
Solution: Use clients for monitoring nearby APs
-
Rogue AP DetectionClients monitor nearby APs. Send to server:MAC address, Channel, SSID, RSSI (for location)Server checks 4-tuple in AP Location DatabaseObtaining AP Information at clients:Same/overlapping channel as client: from BeaconsAP on non-overlapping channel:Active Scan periodicallyAP information from Probe Response
-
Rogue AP Detection Overheads
Bandwidth usage < 0.2 Kbps per client
Can active scans be performed without disruption?Sufficient idleness available (2 3 min.)Simple threshold-based prediction: Active scan completed in idle period for 95% cases
-
Talk OutlineDiagnostics architecture and implementationClient Conduit: diagnosing disconnected clientsDiagnostic mechanismsLocating disconnected clientsDetecting unauthorized APsAnalyzing performance problemsSummary and Future Work
-
SummaryDiagnostics critical for 802.11 deploymentsClient-centric architectureClient ConduitDiagnosis using nearby clientsLocate disconnected clientsDetect rogue APsAnalyze performance problemsPrototype in Windows using Native WiFiMechanisms are effective with low overheads
-
Future Work
Detecting Rogue Ad Hoc networks802.1x protocol analyzerDetailed wireless delay analyzerAutomated recovery after fault diagnosis