Windows L2TP VPN to Cisco ASA Series Firewall

ASA 5500 series firewall <-> Windows L2TP client is not easy because the default setting and wizard can never make it works!  I have to mention that I am talking about Windows client (not other platform, discuss later). 

I will show you how on server configuration (Cisco ASA) later.  Just pay attention to windows client first.  The following steps shows you how to setup a VPN connection on Windows 7:

  1. Start to create a VPN connection likes traditional PPTP VPN
  2. Yes! not different in the very beginning, enter the Server IP Addres and Connection Name
  3. Provide the username and password for login, the domain usually is blank (expert+fool may use it)
  4. Don't connection at once, just finish setup
  5. Find out your connection profile and edit the properties in Adpater Page or click the connection in taskbar and right-click the connection name you just created
  6. In properties, select Security page, specify L2TP/IPSec rather that Auto, this can speed up the negotiation time
  7. Click Advanced (IPSec Setting on XP) to enter a shared key that provided by VPN server (ASA Firewall), this step is a MUST
  8. Optionally, select Network, edit the properties of TCP/IPv4, select Advanced, then uncheck the use remote default gateway if you to keep local network access
  9. Done!  click and make the connection

Have fun!