Virtual Private Network 2003

D.Kartheek murugan

outline What is a VPN? Types of VPN Why use VPNs? Types of VPN protocols Encryption Disadvantage of VPN

What is a VPN? A VPN is A network that uses

Internet or other network service to transmit data. A VPN includes authentication

and encryption to protect data integrity and confidentiality

Types of VPNs Remote Access VPN Provides access to internal corporate

network over the Internet. Reduces long distance, modem bank, and technical support costs.

Types of VPNs Remote Access VPN

Site-to-Site VPN Connects multiple offices over

Internet Reduces dependencies on frame relay

and leased lines

Types of VPNs Remote Access VPN Site-to-Site VPN Extranet VPN 

Provides business partners access to critical information (leads, sales tools, etc)



Reduces transaction and operational costs

Types of VPNs Remote Access VPN Site-to-Site VPN Extranet VPN Intranet VPN:

Links corporate headquarters, remote offices, and branch offices over a shared infrastructure using dedicated connections.

Why Use Virtual Private Networks? 

More flexibility



More scalability



Lower costs

Point-to-Point Tunneling Protocol (PPTP) Layer 2 Tunneling Protocol (L2TP)

Encryption Used to convert data to a secret code for

transmission over an trusted network Encrypted Text

Clear Text “The cow jumped over the moon”

Encryption Algorithm

“4hsd4e3mjvd3sd a1d38esdf2w4d”

Symmetric Encryption Same key used to encrypt and decrypt

message Faster than asymmetric encryption Used by IPSec to encrypt actual message data Examples: DES, 3DES, RC5

Asymmetric Encryption Different keys used to encrypt and

decrypt message (One public, one private) Provides non-repudiation of message or message integrity Examples include RSA, DSA, SHA-1, MD5

Disadvantages of VPN Lower bandwidth available compared

to dial-in line Inconsistent remote access performance due to changes in Internet connectivity No entrance into the network if the Internet connection is broken

Thank you