ZyXEL Communications Internet Security Gateway ZyWALL 2 Series - Manual (Page 238)

ZyWALL 2 Series User’s Guide
14-32 VPN Screens
Table 14-9 VPN Manual Setup
LABEL DESCRIPTION
Secure Gateway
Addr Type the WAN IP address or the URL (up to 31 characters) of the IPSec router with
which you're making the VPN connection.
SPI Type a unique SPI (Security Parameter Index) from one to four characters long. Valid
Characters are "0, 1, 2, 3, 4, 5, 6, 7, 8, and 9".
Encapsulation
Mode Select Tunnel mode or Transport mode from the drop-down list box.
ESP 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).
Encryption
Algorithm Select DES, 3DES or NULL from the drop-down list box.
When DES is used for data communications, both sender and receiver must know
the Encryption 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.
AH 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 next).
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.
Encryption Key
(Only with ESP) With DES, type a unique key 8 characters long. With 3DES, type a unique key 24
characters long. Any characters may be used, including spaces, but trailing spaces
are truncated.