ZyXEL Communications vantage cnm ユーザーズマニュアル

 Chapter 12 VPN Community

Vantage CNM User’s Guide

Encryption Algorithm

Select which key size and encryption algorithm to use in the IKE SA. Choices 

are:
DES - a 56-bit key with the DES encryption algorithm
3DES - a 168-bit key with the DES encryption algorithm
AES - a 128-bit key with the AES encryption algorithm
The ZyWALL and the remote IPSec router must use the same algorithms and 

keys. Longer keys require more processing power, resulting in increased 

latency and decreased throughput.

Authentication 

Algorithm

Select which hash algorithm to use to authenticate packet data in the IKE SA. 

Choices are SHA1 and MD5. SHA1 is generally considered stronger than 

MD5, but it is also slower.

SA Life Time 

(Seconds)

Define the length of time before an IKE SA automatically renegotiates in this 

field. It may range from 180 to 3,000,000 seconds (almost 35 days).

Key Group

Select which Diffie-Hellman key group (DHx) you want to use for encryption 

keys. Choices are:
DH1 - use a 768-bit random number
DH2 - use a 1024-bit random number

Enable Multiple 

Proposals

Select this to allow the ZyWALL to use any of its phase 1 key groups and 

encryption and authentication algorithms when negotiating an IKE SA. 
When you enable multiple proposals, the ZyWALL allows the remote IPSec 

router to select which phase 1 key groups and encryption and authentication 

algorithms to use for the IKE SA, even if they are less secure than the ones 

you configure for the VPN rule.
Clear this to have the ZyWALL use only the configured phase 1 key groups 

and encryption and authentication algorithms when negotiating an IKE SA.

Phase 2

Active Protocol

Select the security protocols used for an SA. 
Both AH and ESP increase processing requirements and communications 

latency (delay).

Encryption Algorithm

Select which key size and encryption algorithm to use in the IKE SA. Choices 

are:
DES - a 56-bit key with the DES encryption algorithm
3DES - a 168-bit key with the DES encryption algorithm
NULL - no encryption key or algorithm
AES - a 128-bit key with the AES encryption algorithm
The ZyWALL and the remote IPSec router must use the same algorithms and 

keys. Longer keys require more processing power, resulting in increased 

latency and decreased throughput.

Authentication 

Algorithm

Select which hash algorithm to use to authenticate packet data in the IPSec 

SA. Choices are SHA1 and MD5. SHA1 is generally considered stronger 

than MD5, but it is also slower.

SA Life Time 

(Seconds)

Define the length of time before an IPSec SA automatically renegotiates in 

this field. The minimum value is 180 seconds.
A short SA Life Time increases security by forcing the two VPN gateways to 

update the encryption and authentication keys. However, every time the VPN 

tunnel renegotiates, all users accessing remote resources are temporarily 

disconnected.

Table 124   VPN Management > VPN Community > Add/Edit (continued)