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ZyWALL 50 Internet Security Gateway
23-14 VPN/IPSec Setup
Table 23-5 Menu 27.1.1.1 — IKE Setup
FIELD DESCRIPTION EXAMPLE
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 300 to 86,400 seconds (one day).
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.
A value of 0 means IKE SA negotiation never times out.
0
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 3DES or DES and then press [ENTER]. DES
Authentication
Algorithm
Press [SPACE BAR] to choose from SHA1 or MD5 and then press [ENTER]. MD5
SA Life Time
(Seconds)[0:
unspecified]
Define the length of time before an IKE Security Association automatically
renegotiates in this field. It may range from 300 to 86,400 seconds (one day).
A value of 0 means IPSec SA never times out.
0
Encapsulation
Press [SPACE BAR] to choose from Tunnel mode or Transport mode and
then press [ENTER]. See earlier for a discussion of these.
Tunnel
Perfect Forward
Secrecy (PFS)
Perfect Forward Secrecy (PFS) is disabled (None) by default in phase 2
IPSec SA setup. This allows faster IPSec setup, but is not so secure. Press
[SPACE BAR] and choose from DH1 or DH2 to enable PFS. DH1 refers to
Diffie-Hellman Group 1 a 768 bit random number. DH2 refers to Diffie-
Hellman Group 2 a 1024 bit (1Kb) random number (more secure, yet slower).
None
When you have completed this menu, press [ENTER] at the prompt “Press ENTER to Confirm…” to save
your configuration, or press [ESC] at any time to cancel.