ZyXEL 4-port Prestige 792H Router 91-004-342001 用户手册

Prestige 792H G.SHDSL Router 

Introduction to IPSec 

 

13-1 

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.