Ph.D. students Department of Electronics and Telecommunications, Politecnico di Torino

Transcription

1 01OPIIU Il softwar libro Dvic-to-dvic communications: Wi-Fi Dirct Laura Cocona s Carlo Borgiattino s Ph.D. studnts Dpartmnt of Elctronics and Tlcommunications, Politcnico di Torino

2 Rport for final valuation 2 Objct: WiFi dirct a comparativ analysis btwn Android and Linux implmntations Outlin: Introduction towifi dirct Implmntation: Android Implmntation: Linux Comparativ analysis

3 3 About intrconncting dvics Nowadays almost all dvics ar quippd with WiFi and Blutooth. How to discovr othr dvics and crat ad-hoc connctions? Wi-Fi Dirct

4 What is WiFi Dirct? 4 Nw tchnology dfind by th WiFi Allianc Enhanc dirct dvic-to-dvic communication in WiFi Entirly implmntd in softwar ovr traditional WiFi radios

5 Architctur - I 5 Wi-Fi Dirct dvics communicat by stablishing P2P groups Dvics can b: P2P Group Ownr (GO): Th dvic implmnting AP-lik functionality in th P2P group o P2P clints: Dvics acting as clints o Lgacy clints: convntional Wi-Fi nods o Rols ar not static: whn two P2P

6 Architctur - II 6 Onc th P2P group is stablishd, othr P2P clints can join th group Lgacy clints can also communicat with th P2P GO. Thy must: Not b b-only dvics o Support th rquird scurity mchanisms o Lgacy clints do not formally blong to th P2P group, but th simply s th P2P GO as a traditional AP

7 Architctur - III 7 cass WiFi Dirct: supportd topologis and

8 P2P GO 8 P2P GO must: Annuncs itslf through bacons o Support powr saving srvics for its associatd clints o Run a DHCP (Dynamic Host Configuration Protocol) srvr o Wi-Fi dirct dos not allow transfrring th rol of P2P GO within a P2P group. Whn th P2P GO lavs th P2P group,

9 T h r P S A t Group u rta 9 n o s d in a o s r tm d o u n ts formation

10 Group formation - Standard 10 Discovry: activ or passiv on Social channls (1,6,11 in th 2.4 GHz band)

11 Group formation - Standard 11 GO Ngotiation: thr-way handshak to agr on rol and channl

12 Group formation - Standard 12 WPS Provisioning (WiFI Protctd Stup)

13 Group formation - Standard 13 Addrss configuration (DHCP)

14 Group formation - Autonomous 14 A P2P dvic immdiatly bcams th P2P GO crating autonomously a P2P group

15 Group formation Prsistnt 15 Usd to quickly r-instantiat th P2P Group using th ntwork crdntials alrady stord in th dvics Invitation procdur (two-way handshak) instad of GO Ngotiation

16 Scurity - I 16 WPS (WiFi Protctd Stup) supports a scur connction btwn WiFi Dvics with minimal usr intrvntion (i.. introducing a PIN in th P2P clint) P2P GO implmnts an intrnal Rgistrar whil P2P clints an Enroll. WPS is basd on WPA-2 scurity

17 Scurity - II 17 Two phass: If th dvic alrady has th rquird ntwork crdntials, it can dirctly prform Phas 2

18 W LA in i nd - 18ur F xo i i d Implmntation

19 Implmntation - Android I 19 Th WiFi Dirct APIs consist of th following main parts: MM t t h h o that allow to discovr, rqust, and o ds connct to prs ar dfind in th d List Li s n st rs n that notify th succss or failur Ir In of s t n t nt s that notify spcific vnts dtctd by th Wi-Fi Dirct framwork, such as a droppd connction or a nwly discovrd pr. n ts

20 20 Implmntation - Android II Th WifiP2pManagr class provids mthods that prmit to intract with th Wi-Fi hardwar on th dvic. Th most important ons ar th following: In Iniziali iz z ia Rgistrs th application with th Wi-Fi C li Con framwork o z nct Starts a pr-to-pr connction with a dvic with th spcifid n configuration. C n CratG r roup at ct Crats a pr-to-pr group with th currnt dvic as th group ownr. R Rqust G Prs q ro Rqusts th currnt list of discovrd prs D u DiscovrP is p rs c st Ini tia R o P Rmov t v Group Rmovs th currnt pr-tos m r pr group o P s

21 21 Implmntation - Android III Stup a P2P Group

22 22 Implmntation - Android IV Rfrncs API ar availabl at oid/nt/wifi/p2p/packag-summary.html Guid is availabl at nnctivity/wifip2p.html

23 Implmntation - Linux I 23

24 Implmntation - Linux II 24 WPA_Supplicant is a damon program that controls th wirlss connction It implmnts ky ngotiation with a WPA Authnticator and it controls IEEE authntication/association of th wlan drivr WPA_Supplicant o Handls th ntir P2P protocol

25 D p 2p v _ vi c sicgrpfl c narolti s ju o rn tv 25ivcunsptd t h c p i_ l_tfn d c t ira n d _s d m c u a _o p d rv d _a q ts u p n p Implmntation - Linux III WPA_supplicant APIs

26 A t h r 26o s Implmntation - Linux Prrquisits

27 C O N F G _ D R V E R _ N L = Implmntation - Linux 27 Wi-Fi P2P is an optional componnt that nds to b nabld in th wpa_supplicant build configuration (.config) Hr is an xampl configuration that includs WiFi P2P support and Linux nl80211 basd drivr intrfac:

28 c r Implmntation - Linux IV _ n 28 In run-tim configuration fil (wpa_supplicant.conf), som paramtrs for P2P must b st: f a c =

29 Implmntation - Linux V 29 Start wpa_supplicant lik this:./wpa_supplicant -Dnl c /path/to/p2p.conf -i wlan0 -dt Thn start./wpa_cli using th primitivs listd bfor

30 Implmntation - Linux 30 Start wpa_supplicant lik this:./wpa_supplicant -Dnl c /path/to/p2p.conf -i wlan0 -dt Thn start./wpa_cli using th primitivs listd bfor p2p_find [wait for pr to b found] p2p_connct <pr-mac-addr> pbc go_intnt=<0..15>

31 Implmntation - Linux 31 Rfrncs: Information about P2P implmntation for Linux ar availabl at WPA_supplicant (hom pag) git clon git://w1.fi/srv/git/hostap.git (download)

32 Comparativ analysis I 32 Both implmntations provid th sam faturs but

33 Comparativ analysis II 33 What do you prfr: a flxibl or an asy to us implmntation?