Module 6: Frames and Network Interaction

Packets vs. Frames

Just discussing the difference between Protocol Data Units (PDUs).

802.11 MAC Frames

MAC Header

802.11 MAC Header

Frame Types

Management Frames

Management frames subtypes:

Subtype	Field Description
0	Association Request
1	Association Response
2	Re-association Request
3	Re-association Response
4	Probe Request
5	Probe Response
6	Measurement Pilot
7	Reserved
8	Beacon
9	ATIM
10	Disassociation
11	Authentication
12	Deauthentication
13	Action
14	Action No ACK
15	Reserved

Beacon frame structure

Although SSID and ESSID are used interchangeably in Wi-Fi tools and AP configuration, there is a small difference. SSID is for single APs. ESSID is when multiple APs in an Extended Service Set (ESS) share the same SSID. The official name of the field in management frames is SSID.

Management frame IE structure

Authentication frame structure

Association request structure

Association response structure

Control Frames

Control frames subtypes:

Subtype	Field Description
0-6	Reserved
7	Control Wrapper
8	Block ACK Request
9	Block ACK
10	PS-Poll
11	RTS
12	CTS
13	ACK
14	CF End
15	CF End + CF-ACK

ACK Frame diagram

RTS/CTS communication sequence

RTS frame structure

CTS frame structure

Data Frames

Data frames subtypes:

Subtype	Field Description
0	Data
1	Data + CF ACK
2	Data + CF Poll
3	Data + CF ACK + CF Poll
4	Null Function (No Data)
5	CF ACK (No Data)
6	CF Poll (No Data)
7	CF ACK + CF Poll (No Data)
8	QoS Data
9	QoS Data + CF ACK
10	QoS Data + CF Poll
11	QoS Data + CF ACK + CF Poll
12	QoS Null (No Data)
13	Reserved
14	QoS CF Poll (No Data)
15	QoS CF ACK + CF Poll (No Data)

Interacting with Networks

The stages in connecting to a network

Open Network

In IEEE 802.11 Wireless Management > Fixed Parameters > Capabilities Information, we can check the Privacy bit to see if the AP is encrypted.

WEP

Same process as the Open Network however the Privacy bit will show it is encrypted. The lack of WPA/WPA2 tags indicates WEP.

EAPoL

Extensible Authentication Protocol over LAN (EAPoL) frames are commonly used during the handshake when connecting to an AP with WPA, WPA2, WPA3, or OWE.

EAPoL-Key frame structures

KDE structure

RSNE structure

RSNE Pairwise Cipher Suite item

WPA1

Advertises WPA1 PSK TKIP.

WPA2

Advertises WPA1 and WPA2, both with AES/CCMP and TKIP.

WPA3

Advertises with SAE in the RSN IE, and 802.11w which is mandatory for WPA3.

OWE

Advertises an RSN IE with OWE, and 802.11w which is also mandatory for OWE.

WPS

Advertises with a WPS beacon tag.