ZyXEL Communications ZyWALL 110 Series, Руководство пользователя, Страница: 56 / 562

Chapter 4 Quick Setup Wizards
ZyWALL 110/310/1100 Series User’s Guide
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• Dead Peer Detection (DPD) has the ZyWALL make sure the remote IPSec device is there
before transmitting data through the IKE SA. If there has been no traffic for at least 15 seconds,
the ZyWALL sends a message to the remote IPSec device. If it responds, the ZyWALL transmits
the data. If it does not respond, the ZyWALL shuts down the IKE SA.
• Authentication Method: Select Pre-Shared Key to use a password or Certificate to use one
of the ZyWALL’s certificates.
4.3.9 VPN Advanced Wizard - Phase 2
Phase 2 in an IKE uses the SA that was established in phase 1 to negotiate SAs for IPSec.
Figure 38
VPN Advanced Wizard: Step 4
• Active Protocol: ESP is compatible with NAT, AH is not.
• Encapsulation: Tunnel is compatible with NAT, Transport is not.
• Encryption Algorithm: 3DES and AES use encryption. The longer the AES key, the higher the
security (this may affect throughput). Null uses no encryption.
• Authentication Algorithm: MD5 gives minimal security and SHA512 gives the highest
security. MD5 (Message Digest 5) and SHA (Secure Hash Algorithm) are hash algorithms used to
authenticate packet data. The stronger the algorithm the slower it is.
• SA Life Time: Set how often the ZyWALL renegotiates the IKE SA. A short SA life time increases
security, but renegotiation temporarily disconnects the VPN tunnel.
• Perfect Forward Secrecy (PFS): Disabling PFS allows faster IPSec setup, but is less secure.
Select DH1, DH2 or DH5 to enable PFS. DH5 is more secure than DH1 or DH2 (although it may
affect throughput). 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. DH5 refers to Diffie-Hellman Group 5 a
1536 bit random number (more secure, yet slower).
• Local Policy (IP/Mask): Type the IP address of a computer on your network. You can also
specify a subnet. This must match the remote IP address configured on the remote IPSec device.
• Remote Policy (IP/Mask): Type the IP address of a computer behind the remote IPSec device.
You can also specify a subnet. This must match the local IP address configured on the remote
IPSec device.
• Nailed-Up: This displays for the site-to-site and remote access client role scenarios. Select this
to have the ZyWALL automatically renegotiate the IPSec SA when the SA life time expires.