My customer is wishing to upgrade from BM37 to BM38. Just now he use BM
for firewall and proxy services. My customer now requires remote access
and wishes to use vpn services. Unfortunately my customer has a rather
strange setup, he uses a cisco firewall/router for direct connection to
the outside world it NATs through to the public interface of the BM
server which is (so the public address is actually a private
ip address range)

Just now the firewall and proxy services provided by BM37 work fine
however, I am slightly concerned that because the public interface isn't
a true public address and the fact that he uses a cisco firewall/router
(which has NATing rules configured in it) before anything hits the BM
server, vpn services won't work.