Virtual Private Network

VPN Overview

• Creates a secure tunnel over a public network  .It doesn't necessarily imply encryption .

• Uses the Internet as the public backbone to access a secure private network.

VPN Protocols

• PPTP (Point-to-Point tunneling Protocol)
• L2F (Layer 2 Forwarding Protocol)
• L2TP (Layer 2 Tunneling Protocol)
• IPSec (Internet Protocol Security)

IPsec

•  Provides Layer 3 security –  Transparent to applications (no need for integrated IPSec support)

•  A set of protocols and algorithms used to secure IP data at
the network layer

•  Combines different components:–  Security associations (SA)
–  Authentication headers (AH)
–  Encapsulating security payload (ESP)
–  Internet Key Exchange (IKE)

•  A security context for the VPN tunnel is established via the
ISAKMP  


Why IPsec?

•  Internet Protocol (IP) is not secure–  IP protocol was designed in the early stages of the Internet where security was not an issue
–  All hosts in the network are known

•  Possible security issues–  Source spoofing
–  Replay packets
–  No data integrity or confidentiality  

Benefits of IPsec•  Confidentiality–  By encrypting data•  Integrity–  Routers at each end of a tunnel calculates the checksum or hash value of the data•  Authentication–  Signatures and certificates
–  All these while still maintaining the ability to route through existing IP networks  

IPsec is designed to provide interoperable, high quality, cryptographically based security for IPv4 and IPv6