ZyXEL Communications P-335WT User Manual

P-335 Series User’s Guide

Chapter 13 VPN Screens

174

Peer ID Type

Select IP to identify the remote IPSec router by its IP address.
Select DNS to identify the remote IPSec router by a domain name.
Select E-mail to identify the remote IPSec router by an e-mail address.

Peer Content

The configuration of the peer content depends on the peer ID type.
For IP, type the IP address of the computer with which you will make the VPN 

connection. If you configure this field to 0.0.0.0 or leave it blank, the Prestige will 

use the address in the Secure Gateway Address field (refer to the Secure 

Gateway Address field description).
For DNS or E-mail, type a domain name or e-mail address by which to identify 

the remote IPSec router. Use up to 31 ASCII characters including spaces, 

although trailing spaces are truncated. The domain name or e-mail address is for 

identification purposes only and can be any string.
It is recommended that you type an IP address other than 0.0.0.0 or use the DNS 

or E-mail ID type in the following situations:
When there is a NAT router between the two IPSec routers. 
When you want the Prestige to distinguish between VPN connection requests 

that come in from remote IPSec routers with dynamic WAN IP addresses. 

Encapsulation 

Mode

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

IPSec 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 Encryption 

Algorithm 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.

Encryption 

Algorithm

Select DES or 3DES from the drop-down list box. The Prestige’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. 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.

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. 

Table 72   Rule Setup (continued)