Chapter 13 Introduction To Ipsec; Vpn Overview; Ipsec; Security Association - ZyXEL Communications ZyWall 35 User Manual

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This chapter introduces the basics of IPSec VPNs.

A VPN (Virtual Private Network) provides secure communications between sites without the

expense of leased site-to-site lines. A secure VPN is a combination of tunneling, encryption,

authentication, access control and auditing technologies/services used to transport traffic over

the Internet or any insecure network that uses the TCP/IP protocol suite for communication.

Internet Protocol Security (IPSec) is a standards-based VPN that offers flexible solutions for

secure data communications across a public network like the Internet. IPSec is built around a

number of standardized cryptographic techniques to provide confidentiality, data integrity and

authentication at the IP layer.

A Security Association (SA) is a contract between two parties indicating what security

parameters, such as keys and algorithms they will use.

Encryption is a mathematical operation that transforms data from "plaintext" (readable) to

"ciphertext" (scrambled text) using a "key". The key and clear text are processed by the

encryption operation, which leads to the data scrambling that makes encryption secure.

Decryption is the opposite of encryption: it is a mathematical operation that transforms

ciphertext to plaintext. Decryption also requires a key.

Chapter 13 Introduction to IPSec

Introduction to IPSec

ZyWALL 35 User's Guide