Chapter 6OutlineTCP/IP ExampleIPv4 HeaderIPv6 HeaderIP Security OverviewSlide 7IP Security ScenarioSlide 9IP Security ArchitectureIPSec Document OverviewIPSec ServicesSecurity Associations (SA)PowerPoint PresentationBefore applying AHTransport Mode (AH Authentication)Tunnel Mode (AH Authentication)Authentication HeaderEnd-to-end versus End-to-Intermediate AuthenticationEncapsulating Security PayloadEncryption and Authentication AlgorithmsESP Encryption and AuthenticationSlide 23Combinations of Security AssociationsSlide 25Slide 26Slide 27Key ManagementOakleyISAKMPRecommended ReadingHenric Johnson 1Chapter 6Chapter 6IP SecurityHenric JohnsonBlekinge Institute of Technology, Swedenhttp://www.its.bth.se/staff/hjo/[email protected] Johnson 2OutlineOutline•Internetworking and Internet Protocols (Appendix 6A)•IP Security Overview•IP Security Architecture•Authentication Header•Encapsulating Security Payload•Combinations of Security Associations•Key ManagementHenric Johnson 3TCP/IP ExampleTCP/IP ExampleHenric Johnson 4IPv4 HeaderIPv4 HeaderHenric Johnson 5IPv6 HeaderIPv6 HeaderHenric Johnson 6IP 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 provide security appropriate for the communication.Henric Johnson 7IP Security OverviewIP Security Overview•Applications of IPSec–Secure branch office connectivity over the Internet–Secure remote access over the Internet–Establsihing extranet and intranet connectivity with partners–Enhancing electronic commerce securityHenric Johnson 8IP Security ScenarioIP Security ScenarioHenric Johnson 9IP Security OverviewIP Security Overview•Benefits of IPSec–Transparent to applications (below transport layer (TCP, UDP)–Provide security for individual users•IPSec can assure that:–A router or neighbor advertisement comes from an authorized router–A redirect message comes from the router to which the initial packet was sent–A routing update is not forgedHenric Johnson 10IP Security ArchitectureIP Security Architecture•IPSec documents:–RFC 2401: An overview of security architecture–RFC 2402: Description of a packet encryption extension to IPv4 and IPv6–RFC 2406: Description of a packet emcryption extension to IPv4 and IPv6–RFC 2408: Specification of key managament capabilitiesHenric Johnson 11IPSec Document IPSec Document OverviewOverviewHenric Johnson 12IPSec ServicesIPSec Services•Access Control•Connectionless integrity•Data origin authentication•Rejection of replayed packets•Confidentiality (encryption)•Limited traffic flow confidentiallityHenric Johnson 13Security Associations Security Associations (SA)(SA)•A one way relationsship between a sender and a receiver.•Identified by three parameters:–Security Parameter Index (SPI)–IP Destination address–Security Protocol IdentifierHenric Johnson 14Transport Mode SATunnel Mode SAAHAuthenticates IP payload and selected portions of IP header and IPv6 extension headersAuthenticates entire inner IP packet plus selected portions of outer IP headerESPEncrypts IP payload and any IPv6 extesion headerEncrypts inner IP packetESP with authenticationEncrypts IP payload and any IPv6 extesion header. Authenticates IP payload but no IP headerEncrypts inner IP packet. Authenticates inner IP packet.Henric Johnson 15Before applying AHBefore applying AHHenric Johnson 16Transport Mode (AH Transport Mode (AH Authentication)Authentication)Henric Johnson 17Tunnel Mode (AH Tunnel Mode (AH Authentication)Authentication)Henric Johnson 18Authentication HeaderAuthentication Header•Provides support for data integrity and authentication (MAC code) of IP packets.•Guards against replay attacks.Henric Johnson 19End-to-end versus End-End-to-end versus End-to-Intermediate to-Intermediate AuthenticationAuthenticationHenric Johnson 20Encapsulating Security Encapsulating Security PayloadPayload•ESP provides confidentiality servicesHenric Johnson 21Encryption and Encryption and Authentication Authentication AlgorithmsAlgorithms•Encryption:–Three-key triple DES–RC5–IDEA–Three-key triple IDEA–CAST–Blowfish•Authentication:–HMAC-MD5-96–HMAC-SHA-1-96Henric Johnson 22ESP Encryption and ESP Encryption and AuthenticationAuthenticationHenric Johnson 23ESP Encryption and ESP Encryption and AuthenticationAuthenticationHenric Johnson 24Combinations of Combinations of Security AssociationsSecurity AssociationsHenric Johnson 25Combinations of Combinations of Security AssociationsSecurity AssociationsHenric Johnson 26Combinations of Combinations of Security AssociationsSecurity AssociationsHenric Johnson 27Combinations of Combinations of Security AssociationsSecurity AssociationsHenric Johnson 28Key ManagementKey Management•Two types:–Manual–Automated•Oakley Key Determination Protocol•Internet Security Association and Key Management Protocol (ISAKMP)Henric Johnson 29OakleyOakley•Three authentication methods:–Digital signatures–Public-key encryption–Symmetric-key encryptionHenric Johnson 30ISAKMPISAKMPHenric Johnson 31Recommended ReadingRecommended Reading•Comer, D. Internetworking with TCP/IP, Volume I: Principles, Protocols and Architecture. Prentic Hall, 1995•Stevens, W. TCP/IP Illustrated, Volume 1: The Protocols. Addison-Wesley,