Hi I use this config: me (VPN client) | | Linux Gateway (NAT) | | Internet | | VPN Server The VPN client (me) is trying to establish connection to the VPN server via a linux NATting gateway. I configured a DES encrypted ESP tunnel and, regardless of the fact that DES unsecure, this works wonderfully. I tried the same with 3DES and ESP. I have a connection time out on the linux box. The client send ESP request but there is no answer coming back to the server. I guess, it's the linux box killing or whatever the packets. The VPN server does not even see the connection attempt. The same I tried in a network with official IP addresses. I had no problems connecting to the vpn server using 3DES and ESP. The Linux gateway is a Suse 7.3 kernel 2.4.10 with iptables 1.2.2. Also ipsec, ipip and ip_gre modules are loaded. Firewall on the gateway is down. If anybody has a solution for that problem, please let me know. thank you Philipp