VPN to OSX from windows machine?
Add this to your registry:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\PolicyAgent]
"AssumeUDPEncapsulationContextOnSendRule"=dword:00000002
Open secpol.msc (click start > search for secpol.msc)


Local Policies > Security Options
Network Security : LAN Manager Auth Level…
Set to: Send LM &amp; NTLMv2 - UseNTLMv2…



And


Network Security : Minimum session security… clients
uncheck "Require 128-bit encryption"


Restart PC
Create VPN Connection on Windows 7

Host Name: (server IP or yourhost.name.com)
PPP Settings : Enable LCP (only)
Type: L2TP/IPSec
Pre-shared key : yoursharedsecret
Data encryption : Optional encryption
Allow CHAO and CHAPv2


Router on server-side must allow VPN Passthrough and forward ports: 50, 51, 500, 548, 1701, 1723, 4500 to the server box. Also, do not filter anonymous internet requests, multicast or NAT Redirection but enable SPI Firewall.