IPv 6 Security Qo S Babu Ram

IPv 6 Security & Qo. S Babu Ram Dawadi 1

Outline • • IP Security Overview IP Security Architecture Authentication Header Encapsulating Security Payload Combinations of Security Associations Key Management Qo. S Overview 2

The need. . . • the most serious involving: – IP spoofing • intruders creating packets with false address then taking advantages of OS exploits – eavesdropping and sniffing • attackers listen for userids and passwords and then just walk into target systems – as a result the IAB included authentication and encryption in the next generation IP (IPv 6) 3

IP Security • We’ve considered some application specific security mechanisms – eg. S/MIME, PGP, Kerberos, SSL/HTTPS • however there are security concerns that cut across protocol layers • would like security implemented by the network for all applications 4

IP Security Overview • IPSec is not a single protocol. • Instead, IPSec provides a set of security algorithms plus a general framework that allows a pair of communicating entities to use whichever algorithms to provide security appropriate for the communication. • Applications of IPSec – Secure branch office connectivity over the Internet – Secure remote access over the Internet – Establisihing extranet and intranet connectivity with partners – Enhancing electronic commerce security 5

IP Security Scenario 6

IPSec • general IP Security mechanisms provides – – – authentication Confidentiality Integrity Obligation key management • applicable to use over LANs, across public & private WANs, & for the Internet 7

Benefits of IPSec • in a firewall/router provides strong security to all traffic crossing the perimeter • is resistant to bypass • is below transport layer, hence transparent to applications • can be transparent to end users • can provide security for individual users if desired • additionally in routing applications: – assure that router advertisments come from authorized routers – neighbor advertisments come from authorized Neighbors – insure redirect messages come from the router to which initial packet was sent – insure no forgoing of router update 8

IPSec Services • Two protocols are used to provide security: – Authentication Header Protocol (AH) – Encapsulation Security Payload (ESP) • Services provided are: – Access control • integrity – Data origin authentication – Rejection of replayed packets • a form of partial sequence integrity – Confidentiality (encryption) – Limited traffic flow confidentiality 9

Security Associations • a one-way relationship between sender & receiver that affords security for traffic flow • defined by 3 parameters: – Security Parameters Index (SPI) • a bit string (which algorithm to use? ) – IP Destination Address • only unicast allowed • could be end user, firewall, router – Security Protocol Identifier • indicates if SA is AH or ESP • has a number of other parameters – seq no, AH & EH info, lifetime etc • have a database of Security Associations 10

Authentication Header (AH) • RFC 2402 • provides support for data integrity & authentication of IP packets – end system/router can authenticate user/app – prevents address spoofing attacks by tracking sequence numbers • based on use of a MAC (message authentication code) – HMAC-MD 5 -96 or HMAC-SHA-1 -96 – MAC is calculated: • immutable IP header fields • AH header (except for Authentication Data field) • the entire upper-level protocol data (immutable) • parties must share a secret key 11

Authentication Header 12

Transport and Tunnel Modes • Both AH and ESP have two modes – transport mode is used to encrypt & optionally authenticate IP data • data protected but header left in clear • can do traffic analysis but is efficient • good for ESP host to host traffic – tunnel mode encrypts entire IP packet • add new header for next hop • good for VPNs, gateway to gateway security 13

Transport & Tunnel Modes 14

Encapsulating Security Payload (ESP) • RFC 2406 • provides message content confidentiality & limited traffic flow confidentiality • can optionally provide the same authentication services as AH • supports range of ciphers, modes, padding – incl. DES, Triple-DES, RC 5, IDEA, CAST etc – CBC most common – pad to meet blocksize, for traffic flow 15

Encapsulating Security Payload 16

Combining Security Associations • SA’s can implement either AH or ESP • to implement both need to combine SA’s – form a security bundle • have 4 cases (see next) 17

Combining Security Associations a. AH in transport mode b. ESP in transport mode c. AH followed by ESP in transport mode(ESP SA inside an AH SA d. any one a, b, c inside an AH or ESP in tunnel mode 18

Key Management • Two types: – Manual – Automated • Oakley Key Determination Protocol • Internet Security Association and Key Management Protocol (ISAKMP) 19

Key Management • handles key generation & distribution • typically need 2 pairs of keys – 2 per direction for AH & ESP • manual key management – sysadmin manually configures every system • automated key management – automated system for on demand creation of keys for SA’s in large systems – has Oakley & ISAKMP elements 20

ISAKMP • Internet Security Association and Key Management Protocol (RFC 2407) • provides framework for key management • defines procedures and packet formats to establish, negotiate, modify and delete SAs • independent of key exchange protocol, encryption algorithm and authentication 21 method

IP Security Architecture • Internet Key Exchange (IKE) A method for establishing a security association (SA) that authenticates users, negotiates the encryption method and exchanges the secret key. IKE is used in the IPsec protocol. Derived from the ISAKMP framework for key exchange and the Oakley and SKEME key exchange techniques, IKE uses public key cryptography to provide the secure transmission of the secret key to the recipient so that the encrypted data may be decrypted at the other end. (http: //computingdictionary. thefreedictionary. com/IKE) 22

IPSec Document Overview 23

Transport Mode SA Tunnel Mode SA AH Authenticates IP payload and selected portions of IP header and IPv 6 extension headers Authenticates entire inner IP packet plus selected portions of outer IP header ESP Encrypts IP payload any IPv 6 extesion header Encrypts inner IP packet ESP with authentication Encrypts IP payload any IPv 6 extesion header. Authenticates IP payload but no IP header Encrypts inner IP packet. Authenticates inner IP packet. 24

Before applying AH 25

Transport Mode (AH Authentication) 26

Tunnel Mode (AH Authentication) 27

ESP Encryption and Authentication 28

ESP Encryption and Authentication 29

Quality–of–Service (Qo. S) • Different semantics or classes of Qo. S: – determines reliability of offered service – utilization of resources max reserved C unused reserved B available resources reserved A time

Resource Reservation • Reservation is fundamental for reliable enforcement of Qo. S guarantees – per-resource data structure (information about all usage) – Qo. S calculations and resource scheduling may be done based on the resource usage pattern – reservation protocols • negotiate desired Qo. S • transfer information about resource requirements and usage • between the end-systems and all intermediate systems – reservation operation • calculate necessary amount of resources based on the Qo. S specifications • reserve resources according to the calculation (or reject request) – resource scheduling • enforce resource usage with respect to resource administration decisions

time Resource Management Phases Phase 1: user’s Qo. S requirements specification rejection or renegotiation admission test and calculation of Qo. S guarantees resource reservation negotiation confirmation Qo. S guarantees to user renegotiation Phase 2: stream termination Qo. S enforcement by proper scheduling enforcement monitoring and adaptation “notification” Phase 3: data transmission renegotiation resource deallocation termination

Reservation Directions • Sender oriented: sender 1. reserve – sender (initiates reservation) data flow • must know target addresses (participants) • in-scalable • good security 2. reserve 3. reserve receiver

Reservation Directions • Receiver oriented: sender 3. reserve – receiver (initiates reservation) • needs advertisement before reservation • must know “flow” addresses – sender • need not to know receivers • more scalable • in-secure data flow 2. reserve 1. reserve receiver

Reservation Directions sender • Combination? 1. reserve – start sender oriented reservation data flow 2. reserve – additional receivers join at routers (receiver based) reserve from nearest router 3. reserve receiver

Qo. S in IPv 6 Protocols • IPv 6 protocols carry a small number of Qo. S-Specific service elements in the IP based & Extension Header • Flows – Sequence of packets sent from a particular source to a particular destination(s) for which the source require special handling in intermediate routers by control protocols like RSVP 37

Flows • Packets that do not belongs to a flow carry a flow level of all zeros. • All packets belonging to the same flow must be sent with same IP source address and destination address with non -zero flow label. • The Flow label field in IPv 6 may be used by source to label packets for which it request special handling by the IPv 6 routers like real time service. 38

IPv 6 extension Headers • Two external headers to signal Qo. S requirements – The Routing extension header can be used to request a specific route by indicating a sequence of IP address. – HOP-by-HOP extension headers can be used to transport a maximum of one router alert signaling message per IP packet to every router on the path of Qo. S-sensitive traffic, indicating that each router should specifically process the packets 39