I am trying to set up a L2TP/IPSec server on AWS with instance running Ubuntu 14.04LTS. I followed the instructions that I found here : https://raymii.org/s/tags/vpn.html.
I tried to use 12.04LTS and 14.04LTS to install the VPN server but both gave me the Error 789 on Windows clients.
Error: 789 "The L2TP connection attempt failed because the security layer encountered a processing error during initial negotiations with the remote computer"
Can anyone give me some idea or suggestion what can I do to fix this ? Is there any better application I should install except from Openswan ? Thanks.
Best Answer
For Windows users, a registry change is required to be able to connect to an IPsec/L2TP VPN behind NAT (e.g. in EC2). Please follow these instructions. Scroll down to the bottom to view separate steps for Windows XP, and for Vista, 7, and Server 2008.