Draytek Vigor2760 series User Manual page 270

Available settings are explained as follows:
Item
IKE Authentication
Method
IPsec Security Method
After finishing all the settings here, please click OK to save the configuration.
Vigor2760 Series User's Guide
Description
This usually applies to those are remote dial-in user or node
(LAN-to-LAN) which uses dynamic IP address and
IPsec-related VPN c
There are two methods offered by Vigor router for you to
authenticate the incoming data coming from remote dial-in
user, Certificate (X.509) and Pre-Shared Key.
Pre-Shared Key- Specify a key for IKE authentication.
Confirm Pre-Shared Key- Retype the characters to
confirm the pre-shared key.
Note: Any packets from the remote dial-in user which does
not match the rule defined in VPN and Remote
Access>>Remote Dial-In User will be applied with the
method specified here.
Medium - Authentication Header (AH) means data will be
authenticated, but not be encrypted. By default, this option
is active.
High (ESP) - Encapsulating Security Payload (ESP) means
payload (data) will be encrypted and authenticated. You
may select encryption algorithm from Data Encryption
Standard (DES), Triple DES (3DES), and AES.
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