ZyXEL Communications ZyWall USG 2000 User Manual page 343

Table 107 VPN > IPSec VPN > VPN Connection > Manual Key > Edit (continued)
LABEL
Encapsulation
Mode
Active Protocol
Encryption
Algorithm
Authentication
Algorithm
ZyWALL USG 2000 User's Guide
DESCRIPTION
Select which type of encapsulation the IPSec SA uses. Choices are
Tunnel - this mode encrypts the IP header information and the data
Transport - this mode only encrypts the data. You should only select
this if the IPSec SA is used for communication between the ZyWALL
and remote IPSec router.
If you select Transport mode, the ZyWALL automatically switches to
Tunnel mode if the IPSec SA is not used for communication between
the ZyWALL and remote IPSec router. In this case, the ZyWALL
generates a log message for this change.
The ZyWALL and remote IPSec router must use the same
encapsulation.
Select which protocol you want to use in the IPSec SA. Choices are:
AH (RFC 2402) - provides integrity, authentication, sequence integrity
(replay resistance), and non-repudiation but not encryption. If you
select AH, you must select an Authentication Algorithm.
ESP (RFC 2406) - provides encryption and the same services offered
by AH, but its authentication is weaker. If you select ESP, you must
select an Encryption Algorithm and Authentication Algorithm.
The ZyWALL and remote IPSec router must use the same protocol.
This field is applicable when the Active Protocol is ESP. Select which
key size and encryption algorithm to use in the IPSec SA. Choices are:
NULL - no encryption key or algorithm
DES - a 56-bit key with the DES encryption algorithm
3DES - a 168-bit key with the DES encryption algorithm
AES128 - a 128-bit key with the AES encryption algorithm
AES192 - a 192-bit key with the AES encryption algorithm
AES256 - a 256-bit key with the AES encryption algorithm
The ZyWALL and the remote IPSec router must use the same
algorithm and key. Longer keys require more processing power,
resulting in increased latency and decreased throughput.
Select which hash algorithm to use to authenticate packet data in the
IPSec SA. Choices are SHA1 and MD5. SHA1 is generally considered
stronger than MD5, but it is also slower.
The ZyWALL and remote IPSec router must use the same algorithm.
Chapter 21 IPSec VPN
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