ZyXEL Communications ZyXEL ZyWALL 5, User Manual

Page: 236 / 668

ZyWALL 5 User’s Guide
234 Chapter 14 VPN Screens
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 DES , 3DES or AES 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 .
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 SHA-1 for maximum security.
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 You must choose a key group for phase 1 IKE setup. DH1 (default) refers to
Diffie-Hellman Group 1 a 768 bit random number. DH2 refers to Diffie-Hellman
Group 2 a 1024 bit (1Kb) random number.
Enable Multiple
Proposals
Select this check box to allow the ZyWALL to use any of its phase 1 or phase 2
encryption and authentication algorithms when negotiating an IPSec SA.
When you enable multiple proposals, the ZyWALL allows the remote IPSec router
to select which encryption and authentication algorithms to use for the VPN
tunnel, even if they are less secure than the ones you configure for the VPN rule.
Clear this check box to have the ZyWALL use only the phase 1 or phase 2
encryption and authentication algorithms configured below when negotiating an
IPSec SA.
Associated
Network Policies
The following table shows the policy(ies) you configure for this rule.
To add a VPN policy, click the add network policy (
) icon in the VPN Rules
(IKE) screen (see Figure 108 on page 229 ). Refer to Section 14.12.2 on page 235
for more information.
# This field displays the policy index number.
Name This field displays the policy name.
Local Network This field displays one or a range of IP address(es) of the computer(s) behind the
ZyWALL.
Remote Network This field displays one or a range of IP address(es) of the remote network behind
the remote IPsec router.
Table 68 VPN Rules (IKE): Gateway Policy: Edit (continued)
LABEL DESCRIPTION