ZyXEL 202H 91-003-194003B Manual Do Utilizador

P-202H Plus v2 User’s Guide

Chapter 11 VPN Screens

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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. 

Encapsulation 

Mode

Select Tunnel mode or Transport mode from the drop-down list box.

Security Protocol

VPN Protocol

Select ESP if you want to use ESP (Encapsulation Security Payload). The ESP 

protocol (RFC 2406) provides encryption as well as some of the services offered 

by AH. If you select ESP here, you must select options from the VPN - Setup and 

Authentication Algorithm fields (described next).
Select AH if you want to use AH (Authentication Header Protocol). The AH 

protocol (RFC 2402) was designed for integrity, authentication, sequence 

integrity (replay resistance), and non-repudiation but not for confidentiality, for 

which the ESP was designed. If you select AH here, you must select options from 

the Authentication Algorithm field (described later).

Pre-Shared Key

Type your pre-shared key in this field. A pre-shared key identifies a 

communicating party during a phase 1 IKE negotiation. It is called "pre-shared" 

because you have to share it with another party before you can communicate 

with them over a secure connection. 
Type from 8 to 31 case-sensitive ASCII characters or from 16 to 62 hexadecimal 

("0-9", "A-F") characters. You must precede a hexadecimal key with a "0x” (zero 

x), which is not counted as part of the 16 to 62 character range for the key. For 

example, in "0x0123456789ABCDEF", “0x” denotes that the key is hexadecimal 

and “0123456789ABCDEF” is the key itself.
Both ends of the VPN tunnel must use the same pre-shared key. You will receive 

a “PYLD_MALFORMED” (payload malformed) packet if the same pre-shared key 

is not used on both ends.

VPN - Setup

Select DES, 3DES or NULL from the drop-down list box. The ZyXEL Device’s 

encryption algorithm should be identical to the secure remote gateway.
When DES is used for data communications, both sender and receiver must 

know 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. 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 SHA-1 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.

Reset

Click Reset to begin configuring this screen afresh.

Table 37   VPN Rule Setup (continued)