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IPv6 Security & QoS

Babu Ram DawadiBabu Ram Dawadi

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OutlineOutline

• IP Security Overview• IP Security Architecture• Authentication Header• Encapsulating Security Payload• Combinations of Security Associations• Key Management• QoS Overview

The need...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 (IPv6)

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IP SecurityIP 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

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IP Security OverviewIP 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

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IP Security ScenarioIP Security Scenario

IPSecIPSec• general IP Security mechanisms

provides– authentication– Confidentiality– Integrity– Obligation– key management

• applicable to use over LANs, across public & private WANs, & for the Internet

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Benefits of IPSecBenefits 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

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IPSec ServicesIPSec 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

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Security AssociationsSecurity 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

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Authentication Header Authentication Header (AH)(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-MD5-96 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

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Authentication HeaderAuthentication Header

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Transport and Tunnel Transport and Tunnel ModesModes

• 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

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Transport & Tunnel Transport & Tunnel ModesModes

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Encapsulating Security Encapsulating Security Payload (ESP)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, RC5, IDEA, CAST etc– CBC most common– pad to meet blocksize, for traffic flow

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Encapsulating Security Encapsulating Security PayloadPayload

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Combining Security Combining Security AssociationsAssociations

• 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)

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Combining Security Combining Security AssociationsAssociations

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 mode18

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Key ManagementKey Management

• Two types:– Manual– Automated

•Oakley Key Determination Protocol• Internet Security Association and Key

Management Protocol (ISAKMP)

Key ManagementKey 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

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ISAKMPISAKMP

• 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 method

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IP Security ArchitectureIP 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://computing-

dictionary.thefreedictionary.com/IKE)

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IPSec Document OverviewIPSec Document Overview

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Transport Mode SA

Tunnel Mode SA

AH Authenticates IP payload and selected portions of IP header and IPv6 extension headers

Authenticates entire inner IP packet plus selected portions of outer IP header

ESP Encrypts IP payload and any IPv6 extesion header

Encrypts inner IP packet

ESP with authentication

Encrypts IP payload and any IPv6 extesion header. Authenticates IP payload but no IP header

Encrypts inner IP packet. Authenticates inner IP packet.

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Before applying AHBefore applying AH

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Transport Mode Transport Mode (AH Authentication)(AH Authentication)

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Tunnel Mode Tunnel Mode (AH Authentication)(AH Authentication)

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ESP Encryption and ESP Encryption and AuthenticationAuthentication

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ESP Encryption and ESP Encryption and AuthenticationAuthentication

QoS in IPv6 ProtocolsQoS in IPv6 Protocols• IPv6 protocols carry a small number of

QoS-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

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FlowsFlows• 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 IPv6 may be used by source to label packets for which it request special handling by the IPv6 routers like real time service.

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IPv6 extension HeadersIPv6 extension Headers• Two external headers to signal QoS

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 QoS-sensitive traffic, indicating that each router should specifically process the packets

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