wi5-aggregation

This repository contains different software tools for implementing and testing 802.11 frame aggregation (A-MPDU and perhaps A-MSDU). For further information about frame aggregation, see this Wikipedia article and its References and External links.

We have started our work with Evan Jones' work "Fake Access Points using Atheros wireless cards in Linux," taken from the following website: http://www.evanjones.ca/software/fakeaps.c

And we extended it to implement the 802.11 authentication and association process.

Our final purpose is to implement frame aggregation (A-MPDU) between a "fake AP" and a normal terminal running 802.11n or 802.11ac.

Note: TO USE THIS SOFTWARE YOU NEED A NETWORK DRIVER THAT SUPPORTS RADIOTAP, OTHERWISE IT MAY CONSIDER THE HEADERS AS PRISM, SO IT WON'T WORK AS EXPECTED.

These changes are being made by Cristian Hernandez in University of Zaragoza, as a part of the H2020 Wi-5 project.

What does this software do?

The main purpose of this software is to send a number of Wi-Fi A-MPDUs, with the aim of measuring the savings they provide.

It creates a "fake AP" called ap0 and starts sending beacons.

When the association of the STA to this "fake AP" is completed, the software runs all the mechanisms required for sending a number of A-MPDUs to it, and ends.

Therefore, it runs all this process:

fakeaps.c            STA that connects
|                      |
|------- Beacon ------>|            The announced SSID is "ap0"
|------- Beacon ------>|
|------- Beacon ------>|
|                      |
|<--- Probe request ---| 
|                      |----------- The association process starts now
|--- Probe response -->|
|<------- ACK ---------|
|                      |
|<--- Auth request ----|
|-------- ACK -------->|
|                      |
|--- Auth response --->|
|<------- ACK ---------|
|                      |
|<--- Assoc request ---|
|-------- ACK -------->|
|                      |
|-- Assoc response --->|
|<------- ACK ---------|
|                      | ------------- The association is completed
|                      |
|                      | ------------- Now the process of sending A-MPDUs can start
|                      |
|--- ADDBA Request --->|               AddBaRequest is an Action frame 
|                      |
|<------- ACK ---------|
|                      |
|<-- ADDBA Response ---|            
|                      |
|-------- ACK -------->|  
|                      |
|-------- A-MPDU ----->|            First A-MPDU
|-------- A-MPDU ----->|
|         ...          |
|-------- A-MPDU ----->|            Last A-MPDU
|                      |
|------ BA Request --->|            Block ACK request
|                      |
|<------- BA  ---------|            Block ACK

How to use the software (with an example)

PC running fakeaps (AP): wlan0 IP address 192.168.7.1; MAC address: 60:e3:27:1d:32:b7.

PC acting as the STA: wlan2 IP address 192.168.7.2; MAC address: f4:f2:6d:0c:9d:aa.

Hardware: two TP-Link TL-WN722N interfaces (one in the "fake AP" and other in the STA):

$lsusb
Bus 001 Device 002: ID 0cf3:9271 Atheros Communications, Inc. AR9271 802.11n

The devices are using the ath9k_htc driver:

$lsmod

(...)
ath9k_htc              48538  0
ath9k_common           12728  1 ath9k_htc
ath9k_hw              322112  2 ath9k_common,ath9k_htc
(...)
ath                    21370  3 ath9k_hw,ath9k_common,ath9k_htc
mac80211              192806  1 ath9k_htc
(...)
cfg80211              137243  3 mac80211,ath,ath9k_htc


$/sbin/modinfo ath9k_htc

filename:       /lib/modules/3.2.0-4-amd64/kernel/drivers/net/wireless/ath/ath9k/ath9k_htc.ko
firmware:       htc_9271.fw
firmware:       htc_7010.fw
description:    Atheros driver 802.11n HTC based wireless devices
license:        Dual BSD/GPL
author:         Atheros Communications

Radiotap headers are used.

Download the files

  $ git clone https://github.com/Wi5/wi5-aggregation.git

Compile the software

  $ gcc --std=gnu99 -Wall -o fakeaps fakeaps.c

Prepare the PC acting as the AP

iwconfig wlan0 mode monitor
ifconfig wlan0 up
ifconfig wlan0 192.168.7.1
iwconfig wlan0 channel 5

Run the software

  ./fakeaps wlan0 5 500 2 10 192.168.7.2 f4:f2:6d:0c:9d:aa

This is the meaning of the parameters:

• wlan0: name of the interface where you are creating the "fake AP". It has to be in monitor mode.
• 5: number of the Wi-Fi channel where you are creating the "fake AP".
• 500: packet size at IP level (including IP header).
• 2: number of packets that are going to travel in an A-MPDU.
• 10: number of A-MPDUs that will be sent.
• 192.168.7.2: IP address of the STA that is going to connect. It will be the destination of the A-MPDUs to be sent.
• f4:f2:6d:0c:9d:aa: MAC address of the STA that is going to connect. The MAC is used as a filter. Only this MAC is allowed to connect to the "fake AP".

Therefore, the previous command would do the next things:

• Create a “fake AP” (called by default ap0) and start sending beacons in broadcast mode in channel 5.
• Wait for the STA with MAC f4:f2:6d:0c:9d:aa to connect, and then send 10 A-MPDUs, each of them containing 2 packets of 500 bytes, to the IP address 192.168.7.2.

Note: if the number of frames in each A-MPDU is set to 0, then the number of A-MPDUs to send will be the number of frames. For example, the command:

  ./fakeaps wlan0 5 500 0 10 192.168.7.2 f4:f2:6d:0c:9d:aa

will just send 10 MPDUs, each of them containing a packet of 500 bytes.

Note: if the number of frames in each A-MPDU is set to 1, then it will send an A-MPDU with a single MPDU, but with A-MPDU format.

Prepare the PC acting as the STA

iwconfig wlan2 mode managed
ifconfig wlan2 up
ifconfig wlan2 192.168.7.2
iwconfig wlan2 channel 5

Connect the STA to the AP

  iwconfig wlan2 essid ap0

After the association of the STA, the software runs all the mechanisms required for sending 10 A-MPDUs (each of them containing 2 packets) to it, and ends.

How to capture the traffic

Prepare another interface (in another computer) in monitor mode:

iw phy phy0 interface add mon0 type monitor
ifconfig mon0 up
iwconfig mon0 channel 5

And capture the traffic:

  tcpdump -e -i mon0 -w /home/proyecto/Aggregation/fakeapscap.pcap

You can see it in Wireshark using this filter:

  wlan.sa == f4:f2:6d:0c:9d:aa || wlan.da == f4:f2:6d:0c:9d:aa || wlan.ra == f4:f2:6d:0c:9d:aa || wlan.ta == f4:f2:6d:0c:9d:aa || wlan.da == 60:e3:27:1d:32:b7 || wlan.sa == 60:e3:27:1d:32:b7 || wlan.ra == 60:e3:27:1d:32:b7 || wlan.ta == 60:e3:27:1d:32:b7