ZyXEL Communications P-661HW User Manual

P-661H/HW Series User’s Guide

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Chapter 13 VPN Screens

There are two phases to every IKE (Internet Key Exchange) negotiation – phase 1 
(Authentication) and phase 2 (Key Exchange). A phase 1 exchange establishes an IKE SA and 
the second one uses that SA to negotiate SAs for IPSec.

Figure 125   Two Phases to Set Up the IPSec SA

In phase 1 you must:

• Choose a negotiation mode.
• Authenticate the connection by entering a pre-shared key.
• Choose an encryption algorithm.

Encryption

Algorithm

Select DES, 3DES, AES or NULL from the drop-down list box. 
When you use one of these encryption algorithms for data communications, both 

the sending device and the receiving device must use the same secret key, which 

can be used to encrypt and decrypt the message or to generate and verify a 

message authentication code. The DES encryption algorithm uses a 56-bit key. 

Triple DES (3DES) is a variation on DES that uses a 168-bit key. As a result, 

3DES is more secure than DES. It also requires more processing power, resulting 

in increased latency and decreased throughput. This implementation of AES uses 

a 128-bit key. AES is faster than 3DES. 
Select NULL to set up a tunnel without encryption. When you select NULL, you 

do not enter an encryption key.

Authentication

Algorithm

Select SHA1 or MD5 from the drop-down list box. MD5 (Message Digest 5) and 

SHA1 (Secure Hash Algorithm) are hash algorithms used to authenticate packet 

data. The SHA1 algorithm is generally considered stronger than MD5, but is 

slower. Select MD5 for minimal security and SHA1 for maximum security. 

Advanced

Click Advanced to configure more detailed settings of your IKE key management. 

Apply

Click Apply to save your changes back to the ZyXEL Device.

Cancel

Click Cancel to begin configuring this screen afresh.

Table 84   Edit VPN Policies