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#ATM15 |
Packets never lie: An in-depth overview of 802.11 frames
George M. Stefanick Jr
@ArubaNetworks
2 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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BIO
George M. Stefanick Jr.
Wireless Architect @ Houston Methodist Hospital – 6 years (7 WiFi Distros, 3,900 aps, 30,000 clients)
Previously worked for a Cisco Partner focused on Mobility for 8 years
Vendor and vendor neutral certifications
www.my80211.com and www.nostringsattachedshow.com (Desperate for friends)
Cisco VIP 2012,2013 and 2014 - Aruba MVP 2014 and 2015 (I have no life)
Consulting (training, site survey, deployment and troubleshooting) (Always indebt to the IRS)
Tech Editor:
Sybex: CCNA Wireless Study Guide; Todd Lammle
Cisco Press: Designing and Deploying 802.11 Wireless Networks: A Practical Guide to Implementing 802.11n and802.11ac; Jim Geier
@ArubaNetworks
3 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Devices that are in my wheelhouse
• Cardiac Imaging
• Electronic Medical Record (EMR)
• Mobile Ultrasound
• Mobile Picture Archiving and Communications systems (PACS)
• RTLS
• Mobile Robots
• Infusion Pumps
• Cows (Computer on Wheels)
• Cisco 7925 Handsets
• Vocera Badges
• Mobile Cisco TelePresence VX Clinical Assistant
• Roche Diagnostics ACCU-CHECK
• Mobile EKG Carts
• Mobile Med Dispensing Carts
• WorkGroup Bridges (WGB)
• Mobile Deaf Response Devices
• DaVinci Simulators
• Laptops
• Tablets
• Smartphones
• Crestron
• Point to Point Links
• Wireless Door Locks
@ArubaNetworks
4 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Quick Poll
1. Who has a WiFi Analyzer in their tool bag ?
2. How confident are you with reading and interpreting your captures ?
3. Who has solved a problem with packet analysis ?
4. Any CWNP Certified folks ?
@ArubaNetworks
5 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Agenda
• This session covers different 802.11 frame types as well as MSDU, MPDU, PSDU, PPDU and other terminology.
• We will explain and showcase some of the common problems you can solve with a packet analyzer.
@ArubaNetworks
6 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Management, Control, and Data frames
Management– Beacon, Association Request, Association
Response, Reassociation Request, ReassociationResponse, Probe Request, Probe Response, Disassociation, Authentication, Deauthentication, Action and Announcement Traffic Indication Message
– Management frames provide the foundation in how WiFi radios are able to detect, join and operate on a WiFi network.
Control– Power Save Poll (PS-Poll), Request to Send (RTS),
Clear to Send (CTS), Acknowledgement (ACK), CF-End +CF +ACK, Block ACK Request (BlockAckReq), and Block ACK (BlockAck).
– Control frames facilitate Data frame delivery. They
are the traffic cops of 802.11 data frames.
Data – Data, NULL, Data+CF-Ack, Data+CF-Poll,
Data+CF-ACK+CF-Poll, CF-ACK, CF-Poll, CF-ACK, Qos Data, QoD Null, QoS Data+CF-ACK, QoSData+CF-Poll, QoS Data +CF-ACK+CF-Poll and more ..
– Data frames are simple. They carry data payload from and to the upper layers.
@ArubaNetworks
7 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Frame Headers, Information Fields, and Information Elements Are Not Encrypted
Layer 2 is not encrypted
Visible to anyone within range of the transmission, on channel and with a protocol analyzer
With the right tools someone can easily ease drop on your network transmissions
WiFi DOS Attacks are easily achieved on Layer 1 and Layer 2
– Layer 2 MFP (Management Frame Protection)
Encryption secures Layer 3 and up (Data Frames)
– NULL Data frames aren’t encrypted because they don’t carry a data payload
@ArubaNetworks
8 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Management Frames
Management
– Beacon, Association Request, Association Response, Reassociation Request, Reassociation Response, Probe Request, Probe Response, Disassociation, Authentication, Deauthentication, Action and Announcement Traffic Indication Message
– Management frames provide the foundation in how WiFi radios are able to detect, join and operate on a WiFi network.
@ArubaNetworks
9 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: What’s inside a Beacon?
@ArubaNetworks
10 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: Broadcast vs NonBroadcast
@ArubaNetworks
11 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: Supported Rates
@ArubaNetworks
12 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: Interval
@ArubaNetworks
13 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: Cipher and AKM (CCMP/802.1X)
@ArubaNetworks
AKM
00-0F-AC-01: 802.1X
00-0F-AC-02: PSK
Cipher Suite
00-0F-AC-01: WEP 40
00-0F-AC-05: WEP 104
00-0F-AC-03: TKIP
00-0F-AC-04: CCMP
Pairwise Cipher
Encryption: Unicast
Group Cipher
Encryption: Multicast / Broadcast
14 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: Cipher and AKM (CCMP/TKIP/802.1X)
@ArubaNetworks
AKM
00-0F-AC-01: 802.1X
00-0F-AC-02: PSK
Cipher Suite
00-0F-AC-01: WEP 40
00-0F-AC-05: WEP 104
00-0F-AC-02: TKIP
00-0F-AC-04: CCMP
Group Cipher
Encryption: Multicast / Broadcast
Pairwise Cipher
Encryption: Unicast
15 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: Cisco Proprietary / Vendor Specific
@ArubaNetworks
AP Name
Station Count
16 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: TIM / DTIM / COUNTRY
@ArubaNetworks
17 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: QBSS Load Station Count / Channel Util.
@ArubaNetworks
Station Count
Channel Utilization
18 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: 802.11n (HT) High Throughput
@ArubaNetworks
19 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: 802.11n (HT) High Throughput
@ArubaNetworks
20 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Beacon: 802.11ac (VHT) Very High Throughput
@ArubaNetworks
21 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Probe: NULL Request
@ArubaNetworks
22 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Probe: Direct Request
@ArubaNetworks
23 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Probe: Request – Remembered Networks
@ArubaNetworks
24 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Probe / Auth / Assoc Flow
@ArubaNetworks
25 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Probe: Request
@ArubaNetworks
26 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Probe: Response
@ArubaNetworks
27 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11: Authentication
@ArubaNetworks
28 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11: Authentication
@ArubaNetworks
29 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11: Association Request
@ArubaNetworks
30 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11: Association Response
@ArubaNetworks
31 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 EAP Flow
@ArubaNetworks
32 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 EAP: ID
@ArubaNetworks
33 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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AirHeads
@ArubaNetworks
How secure is your EAP-PEAPv0 deployment ?
http://community.arubanetworks.com/t5/Technology-Blog/How-secure-is-
your-EAP-PEAPv0-deployment/ba-p/216683
34 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 EAP 4 Way Hand Shake
@ArubaNetworks
35 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Control Frames
@ArubaNetworks
Control
Power Save Poll (PS-Poll), Request to Send (RTS), Clear to Send (CTS), Acknowledgement (ACK), CF-End +CF
+ACK, Block ACK Request (BlockAckReq), and Block ACK (BlockAck).
Control frames facilitate Data frame delivery. Control frames are the traffic cops of 802.11 data frames.
36 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Frame Control Header Retry/To/From/NAV
@ArubaNetworks
37 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 RTS
@ArubaNetworks
38 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 CTS
@ArubaNetworks
39 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 ACK
@ArubaNetworks
40 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Block Acknowledgement Request
@ArubaNetworks
41 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Block Acknowledgement
@ArubaNetworks
42 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Data Frames
@ArubaNetworks
Data
Data, NULL, Data+CF-Ack, Data+CF-Poll, Data+CF-ACK+CF-Poll, CF-ACK, CF-Poll, CF-ACK, Qos Data, QoD Null,
QoS Data+CF-ACK, QoS Data+CF-Poll, QoS Data +CF-ACK+CF-Poll and more ..
Data frames are simple. They carry data payload from and to the upper layers.
43 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Data Encrypted
@ArubaNetworks
44 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Data Not Encrypted
@ArubaNetworks
45 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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802.11 Data NULL Frame
@ArubaNetworks
46 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Sniffing Challenges
@ArubaNetworks
802.11ac
Get close to the radio
Use Aps as sniffers
Build filter and use triggers
Know that you may miss frames
47 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Real World Example – Wireless is slow
@ArubaNetworks
48 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Real World Example – Wireless is slow
@ArubaNetworks
Retry (Frame
Retransmission)
49 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Real World Example – Clients dropping connection
@ArubaNetworks
50 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Real World Example – Clients dropping connection
@ArubaNetworks
NAV 18,800 us
51 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Real World Example – Slow connection lots of application drops
@ArubaNetworks
52 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Real World Example – Slow connection lots of application drops
@ArubaNetworks
NULL
FRAMES
PROBES
Channel
Scanning
53 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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LLC, MAC, PLCP, PMD
@ArubaNetworks
LLC, MAC, PLCP, PMD: Know the layers and what each layer does
54 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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LLC, MAC, PLCP, PMD
@ArubaNetworks
LAYER 2 LLC – Logical Link Control
LAYER 2 MAC – Media Access Control
LAYER 1 PLCP – Physical Layer Convergence Procedure
LAYER 1 PMD – Physical Medium Dependent
55 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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LLC, MAC, PLCP, PMD
@ArubaNetworks
LAYER 2 LLC – Logical Link Control (MSDU) *Packet
LAYER 2 MAC – Media Access Control (MPDU) * Frame
LAYER 1 PLCP – Physical Layer Convergence Procedure(PSDU/PPDU)
LAYER 1 PMD – Physical Medium Dependent (Bits)
56 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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LLC, MAC, PLCP, PMD – Encapsulated Headers
@ArubaNetworks
57 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Spectrum Masks – DSSS / OFDM
@ArubaNetworks
58 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Modulation – 802.11 PRIME and 802.11b
@ArubaNetworks
1 PHY DBPSK
2 PHY DQPSK
5.5 PHY CCK
11 PHY CCK
59 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Modulation – ERP-OFDM 802.11g
@ArubaNetworks
6 PHY BPSK
9 PHY BPSK
12 PHY QPSK
18 PHY QPSK
24 PHY QAM16
36 PHY QAM16
48 PHY QAM64
54 PHY QAM64
60 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Modulation – OFDM 802.11a
@ArubaNetworks
6 PHY BPSK
9 PHY BPSK
12 PHY QPSK
18 PHY QPSK
24 PHY QAM16
36 PHY QAM16
48 PHY QAM64
54 PHY QAM64
61 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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Modulation MIMO-OFDM 802.11n/ac
@ArubaNetworks
62 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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How Bits Get Modulated
@ArubaNetworks
BPSK – 1 bit per modulation symbol at 180 degrees phase
2 wave forms (phases)
63 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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How Bits Get Modulated
@ArubaNetworks
QPSK – 2 bits per modulation symbol at 90 degrees phase
4 wave forms (phases)
64 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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How Bits Get Modulated
@ArubaNetworks
QAM64 – 6 bits per symbol / amplitude modulation
65 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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How Bits Get Modulated
@ArubaNetworks
QAM256 – 8 bits per symbol / amplitude modulation
66 CONFIDENTIAL © Copyright 2015. Aruba Networks, Inc. All rights reserved#ATM15 |
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How Bits Get Modulated
@ArubaNetworks