IPSec provides a framework for securing communications over IP networks by authenticating and encrypting IP packets. It includes protocols for authentication headers and encapsulating security payloads to provide integrity, authentication, and confidentiality. Key management protocols like Oakley and ISAKMP are used to securely establish security associations between communicating parties to protect data flows.

1. IP Security

3. TCP/IP Example

4. Security facilities in the TCP/IP protocol stack

6. IPv4 Header

7. IPv6 Header

11. IP Security Scenario

14. IPSec Document Overview

17. Protocols vs services ESP(encryption and authentication) ESP(encryption only) AH yes yes no Limited traffic flow confidentiality yes yes no confidentiality yes yes yes Rejection of replay attacks yes yes Data origin authentication yes yes Connectionless integrity yes yes yes Access control

20. Security services Encrypts inner IP packet. Authenticates inner IP packet. Encrypts IP payload and any IPv6 extesion header. Authenticates IP payload but no IP header ESP with authentication Encrypts inner IP packet Encrypts IP payload and any IPv6 extesion header ESP Authenticates entire inner IP packet plus selected portions of outer IP header Authenticates IP payload and selected portions of IP header and IPv6 extension headers AH Tunnel Mode SA Transport Mode SA Protocols

28. Before applying AH

29. Transport Mode (AH Authentication)

30. Tunnel Mode (AH Authentication)

31. End-to-end versus End-to-Intermediate Authentication

34. ESP Encryption and Authentication

35. ESP Encryption and Authentication

36. Combinations of Security Associations

37. Combinations of Security Associations

38. Combinations of Security Associations

39. Combinations of Security Associations

47. ISAKMP