A customer is trying to establish a VPN session to our ASP. The customer is using Cisco VPN Client (using IPSec). Their office is using Microsoft Proxy Server 2.0 to get out to the internet. Is it at all possible to establish a VPN connection through the proxy server? According to Cisco, the customer needs to configure the proxy server to open up port 500 UDP (incoming and outgoing) and also add the ESP protocol (protocol 50) on the proxy server. Is this possible on the MS Proxy Server 2.0?