ZyXEL ZyWALL 5 User Guide - Page 366

Chapter 19 IPSec VPN Table 101 SECURITY > VPN > VPN Rules (IKE) > Edit Gateway Policy (continued) LABEL DESCRIPTION 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 Chapter 21 on page 427). 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 AES - a 128/192/256-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. 366 ZyWALL 5/35/70 Series User's Guide