Can't ping or VPN from NAT'd networks
 

I am using IPcop at home and have it configured for VPN access. I can ping my home network public IP from my laptop using Debian if I am connected using the Sprint broadband card. I cannot ping or make a VPN connection when I am connected at work or on some public Wifi. I think the difference is because Sprint gives me a public IP and the other networks give me a private IP. I don't see any errors when I try to make a VPN connection it just initiates the connection and then keeps timing out saying retransmit in...seconds. I am using OpenVPN on my laptop. Any ideas?

While it's a crappy idea it's the only thing I can think of; does the OpenVPN client have a "report public IP" option? Some programs are "smart" enough to realize they're on a NAT and can work around that.

Just a thought.

Actually I posted wrong the first time. I am using OpenSWAN on my IPcop firewall. It does have a public IP option on the VPN configuration, but that shouldn't affect my ability to even ping the public interface I wouldn't think.

Further information...I can ping my home network and make a VPN connection from another home network behind a basic DLink firewall. Now I'm wondering if it has something to do with the firewall on the network I try to connect from. Maybe something like NAT vs. PAT?