Symptoms:
Facts:
Causes: For compliance with export legislation, X-family devices leave the factory supporting only encryption levels below 64 bits. Microsoft Windows Vista (TM) enforces a higher level of IPSec encryption for L2TP VPN connections and so rejects the encryption level offered by the X-family.
Fixes: Install the high encryption software upgrade package on the X-family device. This will enable support for encryption up to 256 bits. Create a new IKE Proposal for 3DES encryption and edit the Default IPSec SA so that it uses the 3DES IKE Proposal.
Here is an example of a common IKE proposal using 3DES that works with the default Windows Vista settings:
Proposal Name: 3DES-SHA1-PSK Encryption: 3DES-CBC Integrity: SHA-1 Diffie-Hellman Group: 2 (1024 bits) Lifetime: 28800 Authentication Type: Pre-Shared Key IKE Phase 2 Setup: Encryption: ESP-3DES-CBC Integrity: ESP-SHA1-HMAC Lifetime: 3600 Enable Perfect Forward Secrecy (Leave the checkbox unchecked) Diffie-Hellman Group: 2 (1024 bits)
— David Gonzalez 2021/04/08 09:45