44D-Link DSL-X1852E User Manual
Section 4 - Conguration
Pre-Shared Key: Enter a pre-shared key to authenticate a remote peer. Up to 16 
characters including symbols can be entered. Both local and remote 
device of the VPN tunnel must use the same pre-shared Key.
Perfect Forward 
Secrecy:
Enable or disable Perfect Forward Secrecy. It uses public key 
cryptography to improve the security of IPSec data communication.
NAT Traversal: Enable or disable NAT traversal for the negotiation of an IPSec VPN 
connection. It allows IPsec VPN trac to pass if NAT is used on the 
gateways.
Key Exchange Phase 1
Exchange Mode: Select Main, Aggressive or Base. In general, Aggressive mode is faster 
than the Main mode but oers less protection against authentication 
security. Unlike the Aggressive and Main Mode, the Base Mode can 
transmit the key exchange information and authentication data 
together .
Encryption 
Algorithm:
Select encryption method as the algorithm for encrypting data 
packets. The options are DES, 3DES, AES-128, AES-192 or AES-256.
Authentication 
Algorithm:
The authentication algorithm validates data packets. Select MD5, 
SHA1, or SHA256. Both local and remote device of the VPN tunnel 
must use the same authentication algorithm. Both MD5 and SHA are 
one-way hashing algorithm but produce dierent number of digest 
bit.
Die-Hellman 
Group:
The Die-Hellman key exchange protocol oers dierent prime key 
lengths. Select 768, 1024, 1536, 2048, 3072, or 4096 bit.
Key Life Time: Enter the amount of time that a key is active in Phase 1. Then select 
the unit: Seconds, Minutes or Hours.
Key Exchange Phase 2