ERP IMPLEMENTATION ERP IMPLEMENTATION Kedar Gaonkar Kedar Gaonkar - - PowerPoint PPT Presentation

SLIDE 1

ERP IMPLEMENTATION ERP IMPLEMENTATION

Kedar Gaonkar Kedar Gaonkar IETF IETF-

• 69 Chicago, July 23rd, 2007

69 Chicago, July 23rd, 2007

SLIDE 2

Deployment Scenario

AP1 STA AP2 Home AAA Local AAA

SLIDE 3

Implementation Implementation

• Setup consists of 4 machines: Supplicant (STA), Access Point

Setup consists of 4 machines: Supplicant (STA), Access Point (AP), and Local AAA Server, and Home AAA Server (AP), and Local AAA Server, and Home AAA Server

– ‘wpa_supplicant ‘wpa_supplicant – – 0.5.7’ at Supplicant 0.5.7’ at Supplicant – ‘HostAP ‘HostAP – – 0.5.7’ at Access Point 0.5.7’ at Access Point – RADIUS implemented at AS by using ‘freeRADIUS RADIUS implemented at AS by using ‘freeRADIUS – – 1.1.6’ 1.1.6’

• EAP

EAP-

• TLS selected as the EAP method

TLS selected as the EAP method

• OpenSSL used to generate certificates

OpenSSL used to generate certificates

• STA associates with AP wirelessly through DWL

STA associates with AP wirelessly through DWL-

• G650 network

G650 network cards (Atheros Chipset) cards (Atheros Chipset)

• AP is connected to Local AAA by a CAT5 cross

AP is connected to Local AAA by a CAT5 cross-

• cable

cable

• Local AAA and Home AAA exist on common LAN.

Local AAA and Home AAA exist on common LAN.

SLIDE 4

EAP Peer State Machine EAP Peer State Machine

INITIALIZE INITIALIZE METHOD METHOD RECEIVED RECEIVED DISCARD DISCARD SEND_RESPONSE SEND_RESPONSE IDLE IDLE eapReq eapReq rxReq&&reqId!=lastId&&reqMethod!=IDENTITY rxReq&&reqId!=lastId&&reqMethod!=IDENTITY rxReq&&reqId!=lastId&&(reqMethod== rxReq&&reqId!=lastId&&(reqMethod== selectedMethod)&&(methodState!=DONE) selectedMethod)&&(methodState!=DONE) else else selectedMethod == reqMethod selectedMethod == reqMethod ignore ignore (altAccept&&decision!=FAIL)||(idleWhile==0&& (altAccept&&decision!=FAIL)||(idleWhile==0&& decision==UNCOND_SUCC) decision==UNCOND_SUCC) NOTIFICATION NOTIFICATION RETRANSMIT RETRANSMIT FAILURE FAILURE SUCCESS SUCCESS GET_METHOD GET_METHOD IDENTITY IDENTITY rxSuccess rxSuccess && && decision!=FAIL decision!=FAIL rxSuccess&&decision==FAIL rxSuccess&&decision==FAIL rxReq&&reqId==lastId rxReq&&reqId==lastId rxReq&&reqId!=lastId&&reqMethod==NOTIFICATION rxReq&&reqId!=lastId&&reqMethod==NOTIFICATION rxReq&&reqId!=lastId&&reqMethod==IDENTITY rxReq&&reqId!=lastId&&reqMethod==IDENTITY rxReq&&reqId!=lastId&&reqMethod!=IDENTITY rxReq&&reqId!=lastId&&reqMethod!=IDENTITY &&reqMethod!=NOTIFICATION &&reqMethod!=NOTIFICATION else else altReject||(idleWhile==0&&decision!=UNCOND_SUCC)||(altAccept&&methodState altReject||(idleWhile==0&&decision!=UNCOND_SUCC)||(altAccept&&methodState !=CONT&&decision==FAIL) !=CONT&&decision==FAIL)

SLIDE 5

Peer ERP State Machine

RECEIVED RECEIVED IDLE IDLE ER_INITIATE ER_INITIATE eapRespData = buildERauth(reqId) eapRespData = buildERauth(reqId) portValid = FALSE portValid = FALSE eapSuccess = FALSE eapSuccess = FALSE SEND_ER_INITIATE SEND_ER_INITIATE eapResp = TRUE erAuthenticate = FALSE eapResp = TRUE erAuthenticate = FALSE eapRespData eapRespData INITIALIZE INITIALIZE erAuthCount = 0 erAuthCount = 0 erAuthCount > 2 erAuthCount > 2 Connect to new AP Connect to new AP (EMSK valid) (EMSK valid) eapReq eapReq erFinish erFinish

rxReq&&reqId!=lastId rxReq&&reqId!=lastId &&reqMethod!=IDENTITY &&reqMethod!=IDENTITY

(EMSK valid) (EMSK valid) Timer Expires Timer Expires eapResp = TRUE, erAuthenticate = FALSE eapResp = TRUE, erAuthenticate = FALSE erValidReceive = FALSE erValidReceive = FALSE erAuthCount = 0 erAuthCount = 0 erAuthenticate erAuthenticate RETRANSMIT RETRANSMIT !erValidReceive !erValidReceive FAILURE FAILURE SUCCESS SUCCESS rxSuccess&&decision == FAIL rxSuccess&&decision == FAIL rxSuccess rxSuccess && && decision!=FAIL decision!=FAIL

SLIDE 6

Peer Eapol Backend State Machine Peer Eapol Backend State Machine

INITIALIZE INITIALIZE REQUEST REQUEST IDLE IDLE

eapolEap&&suppStart eapolEap&&suppStart eapResp eapResp eapSuccess eapSuccess

RECEIVE RECEIVE

erTimeoutWhen = erTimeoutPeriod erTimeoutWhen = erTimeoutPeriod

SUCCESS SUCCESS TIMEOUT TIMEOUT FAIL FAIL RESPONSE RESPONSE

If(!erValidReceive) If(!erValidReceive) { erAuthenticate = TRUE { erAuthenticate = TRUE erAuthCount++ erAuthCount++ } eapResp eapResp eapFail eapFail erTimeoutWhen == 0 erTimeoutWhen == 0 eapSuccess eapSuccess

SLIDE 7

Authenticator EAPOL State Machine Authenticator EAPOL State Machine

INITIALIZE INITIALIZE IDLE IDLE REQUEST REQUEST ER_INITIATE ER_INITIATE

eapSuccess = FALSE eapSuccess = FALSE eapolERP = FALSE eapolERP = FALSE eapResp = TRUE eapResp = TRUE eapNoReq = FALSE eapNoReq = FALSE aWhile = serverTimeout aWhile = serverTimeout sendRespToServer() sendRespToServer() eapolERP eapolERP eapolEap eapolEap

eapReq&&authStart eapReq&&authStart eapolEap eapolEap

eapReq eapReq eapFail&&authStart eapFail&&authStart eapolERP eapolERP

RESPONSE RESPONSE IGNORE IGNORE FAIL FAIL TIMEOUT TIMEOUT SUCCESS SUCCESS

eapReq&& eapReq&& !eapolERP !eapolERP

eapSuccess eapSuccess eapFail eapFail eapTimeout eapTimeout aWhile == 0 aWhile == 0 eapNoReq eapNoReq aWhile == 0 aWhile == 0 eapFail eapFail eapSuccess eapSuccess

eapolEap eapolEap

p q p q

SLIDE 8

Message Validation and Key Derivation at AS

Decapsulate EAP Message Decapsulate EAP Message Check SEQ Check SEQ Lookup rIKname Lookup rIKname else else

EAP_INITIATE EAP_INITIATE

pass pass else else Compare Integrity Checksum Compare Integrity Checksum DISCARD DISCARD pass pass pass pass else else Generate rMSK Generate rMSK rMSK = TLS rMSK = TLS-

• PRF

PRF-

• 64(rRK, SEQ)

64(rRK, SEQ)

SLIDE 9

Send EAP_FINISH to AP

Build EAP Build EAP-

• Finish Packet

Finish Packet Flags=000 Flags=000 Build EAP Build EAP-

• Finish Packet

Finish Packet Flags=100 Flags=100 Validation Successful? Validation Successful? Yes Yes No No Encapsulate into Encapsulate into ACCESS ACCEPT ACCESS ACCEPT Encapsulate into Encapsulate into ACCESS REJECT ACCESS REJECT Send RADIUS packet to AP Send RADIUS packet to AP Add RADIUS Attributes Add RADIUS Attributes

SLIDE 10

Message Validation and Key Derivation at Peer

Decapsulate EAP Message Decapsulate EAP Message Check SEQ Check SEQ Lookup rIKname Lookup rIKname else else

EAP_FINISH EAP_FINISH

pass pass else else Compare Integrity Checksum Compare Integrity Checksum DISCARD DISCARD pass pass Pass Pass else else Generate rMSK Generate rMSK rMSK = TLS rMSK = TLS-

• PRF

PRF-

• 64(rRK, SEQ)

64(rRK, SEQ) erValidReceive = TRUE erValidReceive = TRUE 4-

• way key exchange

way key exchange FAIL FAIL Flags ==000 Flags ==000 Flags ==100 Flags ==100

SLIDE 11

New RADIUS attributes proposed New RADIUS attributes proposed

• Local AAA server requests key from Home AAA server

Local AAA server requests key from Home AAA server

• Two new RADIUS Attributes:

Two new RADIUS Attributes: – Key Key-

• Request Attribute

Request Attribute – Key Key-

• Response Attribute

Response Attribute

SLIDE 12

Initial EAP exchange

EAP Response/Identity EAP Response/Identity RADIUS Access RADIUS Access-

• Req

Req [Username, NAS [Username, NAS-

• IP

IP-

• Addr, NAS

Addr, NAS-

• Port,

Port, Called Called-

• StationID, Calling

StationID, Calling-

• StationID,

StationID, Framed MTU, NAS Framed MTU, NAS-

• Port

Port-

• Type, Connect

Type, Connect-

• Info,

Info, EAP EAP-

• Message, Message

Message, Message-

• Authenticator]

Authenticator] [Username NAS [Username NAS-IP IP-Addr NAS Addr NAS-Port Port RADIUS Access RADIUS Access-

• Req

Req

Peer Peer AP2 AP2 Local AAA Local AAA Home AAA Home AAA

EAP Request/Identity EAP Request/Identity [Username, NAS [Username, NAS-IP IP-Addr, NAS Addr, NAS-Port, Port, Called Called-

• StationID, Calling

StationID, Calling-

• StationID,

StationID, Framed MTU, NAS Framed MTU, NAS-

• Port

Port-

• Type, Connect

Type, Connect-

• Info,

Info, EAP EAP-

• Message, Message

Message, Message-

• Authenticator,

Authenticator, Key Key-

• Request

Request] RADIUS Access RADIUS Access-

• Accept

Accept [MS [MS-

• MPPE

MPPE-Recv Recv-

• Key, MS

Key, MS-

• MPPE

MPPE-Send Send-

• Key, EAP

Key, EAP-

• Finish/Reauth

Finish/Reauth-

• Message,

Message, Message Message-

• Authenticator, Username,

Authenticator, Username, Session Session-

• Timeout,

Timeout, Key Key-

• Response

Response] RADIUS Access RADIUS Access-

• Accept

Accept [MS [MS-

• MPPE

MPPE-

• Recv

Recv-

• Key, MS

Key, MS-

• MPPE

MPPE-

• Send

Send-

• Key,

Key, EAP EAP-

• Finish/Reauth

Finish/Reauth-

• Message, Message

Message, Message-

• Authenticator, Username, Session

Authenticator, Username, Session-

• Timeout]

Timeout] EAP Success EAP Success EAP Method Exhange EAP Method Exhange

SLIDE 13

During ERP Reauthentication

[SEQ, rIK name, rIKname as NAI,Crypto [SEQ, rIK name, rIKname as NAI,Crypto Suite, Authentication Tag] Suite, Authentication Tag] EAP Initiate/Reauth EAP Initiate/Reauth RADIUS Access RADIUS Access-

• Req

Req [Username, NAS [Username, NAS-

• IP

IP-

• Addr, NAS

Addr, NAS-

• Port,

Port, Called Called-

• StationID, Calling

StationID, Calling-

• StationID,

StationID, Framed MTU, NAS Framed MTU, NAS-

• Port

Port-

• Type, Connect

Type, Connect-

• Info,

Info, EAP EAP-

• Message, Message

Message, Message-

• Authenticator]

Authenticator]

Peer Peer AP2 AP2 Local AAA Local AAA Home AAA Home AAA

No need to Contact No need to Contact RADIUS Access RADIUS Access-

• Accept

Accept [MS [MS-

• MPPE

MPPE-

• Recv

Recv-

• Key, MS

Key, MS-

• MPPE

MPPE-

• Send

Send-

• Key,

Key, EAP EAP-

• Finish/Reauth

Finish/Reauth-

• Message, Message

Message, Message-

• Authenticator, Username, Session

Authenticator, Username, Session-

• Timeout]

Timeout] EAP Finish/Reauth EAP Finish/Reauth [SEQ, rIK name, rIKname as NAI,Crypto Suite, [SEQ, rIK name, rIKname as NAI,Crypto Suite, Authentication Tag] Authentication Tag] Home AAA Server Home AAA Server

SLIDE 14

Acknowledgments

• freeRADIUS Team
• Host AP and wpa_supplicant : Jouni

M li Malinen

SLIDE 15

Thank You!

Questions? Questions?