HP-UX IPSec version A.02.01 Administrator's Guide

HP-UX IPSec Overview
HP-UX IPSec Topologies
Chapter 156
In Figure 1-15, the supplier and manufacturer have separate intranets
that are connected to the public Internet using Internet Service
Providers (ISPs). System A on the supplier’s intranet and System B on
the manufacture’s subnet communicate with a host-to-host IPsec
topology. For added security, you can configure filtering on the
manufacturer’s firewall so that it checks the traffic to and from system A
and allows only IPsec packets between system A and B to pass.
Figure 1-15 HP-UX IPSec Host-to-Host VPN Across the Internet