Hi
I have problems with connection WinXP l2tp ipsec client to Linux 2.6.6 with racoon.
In case the NAT isn't between client and server everything is ok but when client is behind NAT occurs broblems with connecition.
I applied WinXP update ( L2TP/PISec NAT-t update) and racoon is configure with NAT-T. On my server my firewall have open ports for ISKMP ( 500 ), L2TP (1701), and NAT-T (4500) and permits peckets of  ESP protocol.
When I applied tcpdump on server interface there are any packets on 4500 port ( NAT-T) only on port 500. The key negotiation ends on phase1.
Have somebody the same problem??Know somebody the solution of this problem.
Thanks and sorry for my English!!
Best regards
Tomek