Vpn Advanced Wizard - Phase 2 - ZyXEL Communications ZyWall ATP series User Manual

Note: The remote IPSec device must also have NAT traversal enabled. See the help in the
main IPSec VPN screens for more information.
• Dead Peer Detection (DPD) has the Zyxel Device 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 Zyxel
Device sends a message to the remote IPSec device. If it responds, the Zyxel Device transmits the
data. If it does not respond, the Zyxel Device shuts down the IKE SA.
• Authentication Method: Select Pre-Shared Key to use a password or Certificate to use one of the Zyxel
Device'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 67 VPN Advanced Wizard: Phase 2 Settings
• 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 Zyxel Device 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.
Chapter 4 Quick Setup Wizards
ZyWALL ATP Series User's Guide
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