from the webpage:> It´s an IPSec problem. I don´t want to go into detail but you probably should try NAT-Traversal. > For the theory http://www.ipsec-howto.org/x180.html
Okay, I've read the reference. If I understand correctly, I need to use a NAT methodology that implements "NAT Traversal" (the reference is a little vague on this; in fairness, it does say "There are no RFCs at the moment"). It might be therefore fair to say that the Linksys implementation includes NAT Traversal, enabling it to handle multiple IPSec passthrough connections.
Which leads me to what I suppose was the original question, now slightly modified: does iptables support NAT Traversal?
"What does NAT traversal do to help? NAT-traversal again encapsulates the ESP packets in UDP packets. These can easily be handled by a NAT device since they provide ports."
So you have to activate on your clients the NAT-T "feature" and be sure the other side supports it too.
And to answer your question, yes every NAT device should be able to handle multiple IPSec NAT-Ted connections because they are wrapped within UDP packets and so every connection can be tracked. Essentially is that both sides which use IPSec are aware of NAT-T and it is correctly configured.
