ZyXEL Communications Prestige 792H, User Manual

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Prestige 792H User’s Guide
36-12 VPN/IPSec Setup
Table 36-3
Menu 27.1.1.1 IKE Setup
FIELD DESCRIPTION EXAMPLE
Encryption
Algorithm 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. Prestige
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 slightly increased latency and decreased throughput.
Press [SPACE BAR] to choose from 3DES or DES and then press [ENTER].
DES
Authentication
Algorithm
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 slightly slower.
Press [SPACE BAR] to choose from SHA1 or MD5 and then press [ENTER].
SHA1
SA Life Time
(Seconds)
Define the length of time before an IKE Security Association automatically
renegotiates in this
field. It may range from 60 to 3,000,000 seconds (almost
35 days).
A short SA Life Time increases security by forcing the two VPN gateways to
update the encryption and authentication keys. However, every time the VPN
tunnel renegotiates, all users accessing remote resources are temporarily
disconnected.
28800
(default)
Key Group You must choose a key group for phase 1 IKE setup. DH1 (default) refers to
Diffie-Hellman Group 1 a 768 bit random number. DH2 refers to Diffie-Hellman
Group 2 a 1024 bit (1Kb) random number.
DH1
Phase 2
Active Protocol Press [SPACE BAR] to choose from ESP or AH and then press [ENTER]. See
earlier for a discussion of these protocols.
ESP
Encryption
Algorithm
Press [SPACE BAR] to choose from NULL , 3DES or DES and then press
[ENTER]. Select NULL to set up a tunnel without encryption.
DES
Authentication
Algorithm
Press [SPACE BAR] to choose from SHA1 or MD5 and then press [ENTER]. MD5
SA Life Time
(Seconds)
Define the length of time before an IPSec Security Association automatically
renegotiates in this
field. It may range from 60 to 3,000,000 seconds (almost
35 days).
28800
(default)
Encapsulation Press [SPACE BAR] to choose from Tunnel mode or Transport mode and
then press [ENTER]. See earlier for a discussion of these.
Tunnel