1a6085186SLina Ceballos<!-- 2ea75aaf6SJiao XianjunAuthor: Michael Mehari 3ea75aaf6SJiao XianjunSPDX-FileCopyrightText: 2019 UGent 4a6085186SLina CeballosSPDX-License-Identifier: AGPL-3.0-or-later 5a6085186SLina Ceballos--> 67273ec43Smmehari 77273ec43Smmehari## 802.11 packet injection 87273ec43Smmehari 97273ec43SmmehariThe Linux wireless networking stack (i.e. driver, mac80211, cfg80211, net_dev, user app) is a robust implementation supporting a plethora of wireless devices. As robust as it is, it also has a drawback when it comes to single-layer testing. 107273ec43Smmehari 117273ec43SmmehariPing and Iperf are well established performance measurement tools. However, using such tools to measure 802.11 PHY performance can be misleading, simply because they touch multiple layers in the network stack. 127273ec43Smmehari 137273ec43SmmehariLuckily, the mac80211 Linux subsystem provides packet injection functionality and it allows us to have finer control over physical layer testing. 147273ec43Smmehari 157273ec43SmmehariTo this end, we have adapted a [packetspammer](https://github.com/gnychis/packetspammer) application originally written by Andy Green <[email protected]> and maintained by George Nychis <[email protected]>. 167273ec43Smmehari 17*fdbf6a5aSJiao Xianjun### Build inject_80211 on board 187273ec43SmmehariUserspace program to inject 802.11 packets through mac80211 supported (softmac) wireless devices. 197273ec43Smmehari 20*fdbf6a5aSJiao XianjunLogin/ssh to the board, then 21*fdbf6a5aSJiao Xianjun``` 22*fdbf6a5aSJiao Xianjuncd openwifi/inject_80211 23*fdbf6a5aSJiao Xianjunmake 24*fdbf6a5aSJiao Xianjun``` 25*fdbf6a5aSJiao Xianjun 267273ec43Smmehari### Options 277273ec43Smmehari ``` 287273ec43Smmehari-m/--hw_mode <hardware operation mode> (a,g,n) 297273ec43Smmehari-r/--rate_index <rate/MCS index> (0,1,2,3,4,5,6,7) 307273ec43Smmehari-i/--sgi_flag (0,1) 317273ec43Smmehari-n/--num_packets <number of packets> 327273ec43Smmehari-s/--payload_size <payload size in bytes> 337273ec43Smmehari-d/--delay <delay between packets in usec> 347273ec43Smmehari-h this menu 357273ec43Smmehari ``` 367273ec43Smmehari 377273ec43Smmehari### Example: 387273ec43Smmehari``` 397273ec43Smmehariiw dev wlan0 interface add mon0 type monitor && ifconfig mon0 up 407273ec43Smmehariinject_80211 -m n -r 0 -n 64 -s 100 mon0 # Inject 10 802.11n packets at 6.5Mbps bitrate and 64bytes size 417273ec43Smmehari``` 427273ec43Smmehari 437273ec43Smmehari### Link performance test 447273ec43Smmehari 457273ec43SmmehariTo make a profound experimental analysis on the physical layer performance, we can rely on automation scripts. 467273ec43Smmehari 477273ec43SmmehariThe following script will inject 100 802.11n packets at different bitrates and payload sizes. 487273ec43Smmehari 497273ec43Smmehari``` 507273ec43Smmehari#!/bin/bash 517273ec43Smmehari 527273ec43SmmehariHW_MODE='n' 537273ec43SmmehariCOUNT=100 547273ec43SmmehariDELAY=1000 557273ec43SmmehariRATE=( 0 1 2 3 4 5 6 7 ) 567273ec43SmmehariSIZE=( $(seq -s' ' 50 100 1450) ) # paload size in bytes 577273ec43SmmehariIF="mon0" 587273ec43Smmehari 597273ec43Smmeharifor (( i = 0 ; i < ${#PAYLOAD[@]} ; i++ )) do 607273ec43Smmehari for (( j = 0 ; j < ${#RATE[@]} ; j++ )) do 617273ec43Smmehari inject_80211 -m $HW_MODE -n $COUNT -d $DELAY -r ${RATE[$j]} -s ${SIZE[$i]} $IF 627273ec43Smmehari sleep 1 637273ec43Smmehari done 647273ec43Smmeharidone 657273ec43Smmehari 667273ec43Smmehari``` 677273ec43Smmehari 687273ec43SmmehariOn the receiver side, we can use tcpdump to collect the pcap traces. 697273ec43Smmehari 707273ec43Smmehari``` 717273ec43Smmehariiw dev wlan0 interface add mon0 type monitor && ifconfig mon0 up 727273ec43Smmeharitcpdump -i mon0 -w trace.pcap 'wlan addr1 ff:ff:ff:ff:ff:ff and wlan addr2 66:55:44:33:22:11' 737273ec43Smmehari``` 747273ec43Smmehari 757273ec43SmmehariWlan addresses *ff:ff:ff:ff:ff:ff* and *66:55:44:33:22:11* are specific to our injector application. 767273ec43Smmehari 777273ec43SmmehariNext, we analyze the collected pcap traces using the analysis tool provided. 787273ec43Smmehari 797273ec43Smmehari``` 807273ec43Smmeharianalyze_80211 trace.pcap 817273ec43Smmehari``` 827273ec43Smmehari 837273ec43SmmehariAn excerpt from a sample analysis looks the following 847273ec43Smmehari 857273ec43Smmehari``` 867273ec43SmmehariHW MODE RATE(Mbps) SGI SIZE(bytes) COUNT Duration(sec) 877273ec43Smmehari======= ========== === =========== ===== ============= 887273ec43Smmehari802.11n 6.5 OFF 54 100 0.11159 897273ec43Smmehari802.11n 13.0 OFF 54 100 0.11264 907273ec43Smmehari802.11n 19.5 OFF 54 100 0.11156 917273ec43Smmehari802.11n 26.0 OFF 54 100 0.11268 927273ec43Smmehari802.11n 39.0 OFF 54 100 0.11333 937273ec43Smmehari802.11n 52.0 OFF 54 100 0.11149 947273ec43Smmehari802.11n 58.5 OFF 54 100 0.11469 957273ec43Smmehari802.11n 65.0 OFF 54 100 0.11408 967273ec43Smmehari``` 977273ec43Smmehari 98