ZyXEL 2WG Guida Utente

Chapter 15 IPSec VPN Screens

ZyWALL 2WG User’s Guide

Server Mode

Select Server Mode to have this ZyWALL authenticate extended authentication 

clients that request this VPN connection. 
You must also configure the extended authentication clients’ usernames and 

passwords in the authentication server’s local user database or a RADIUS server 

(see 

Click Local User to go to the Local User Database screen where you can view 

and/or edit the list of user names and passwords. Click RADIUS to go to the 

RADIUS screen where you can configure the ZyWALL to check an external 

RADIUS server.
During authentication, if the ZyWALL (in server mode) does not find the extended 

authentication clients’ user name in its internal user database and an external 

RADIUS server has been enabled, it attempts to authenticate the client through 

the RADIUS server.

Client Mode

Select Client Mode to have your ZyWALL use a username and password when 

initiating this VPN connection to the extended authentication server ZyWALL. 

Only a VPN extended authentication client can initiate this VPN connection.

User Name

Enter a user name for your ZyWALL to be authenticated by the VPN peer (in 

server mode). The user name can be up to 31 case-sensitive ASCII characters, 

but spaces are not allowed. You must enter a user name and password when you 

select client mode.

Password

Enter the corresponding password for the above user name. The password can 

be up to 31 case-sensitive ASCII characters, but spaces are not allowed.

IKE Proposal

Negotiation Mode

Select Main or Aggressive from the drop-down list box. Multiple SAs connecting 

through a secure gateway must have the same negotiation mode.

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
AES128 - a 128-bit key with the AES encryption algorithm
AES192 - a 192-bit key with the AES encryption algorithm
AES256 - a 256-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).
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. 

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
DH5 - use a 1536-bit random number
The longer the key, the more secure the encryption, but also the longer it takes to 

encrypt and decrypt information. Both routers must use the same DH key group.

Table 85   SECURITY > VPN > VPN Rules (IKE) > Edit Gateway Policy  (continued)