ZyXEL Communications USG 2000 manual 450

Chapter 25 IPSec VPN

Table 118 Configuration > VPN > IPSec VPN > VPN Connection > Edit (continued)

LABEL	DESCRIPTION
Encryption	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 both have at least one
	proposal that uses use the same encryption and the same key.
	Longer keys are more secure, but require more processing power,
	resulting in increased latency and decreased throughput.
Authentication	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 the remote IPSec router must both have a proposal
	that uses the same authentication algorithm.
Perfect	Select whether or not you want to enable Perfect Forward Secrecy
Forward	(PFS) and, if you do, which Diffie-Hellman key group to use for
Secrecy (PFS)	encryption. Choices are:
	none - disable PFS
	DH1 - enable PFS and use a 768-bit random number
	DH2 - enable PFS and use a 1024-bit random number
	DH5 - enable PFS and use a 1536-bit random number
	PFS changes the root key that is used to generate encryption keys for
	each IPSec SA. The longer the key, the more secure the encryption,
	but also the longer it takes to encrypt and decrypt information. Both
	routers must use the same DH key group.
Connectivity	The ZyWALL can regularly check the VPN connection to the gateway
Check	you specified to make sure it is still available.
Enable	Select this to turn on the VPN connection check.
Connectivity
Check

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	ZyWALL USG 2000 User’s Guide