"User management and the related cryptographic authentication
infrastructure is a major hurdle in deploying scalable, manageable
VPNs (Virtual Private Networks). After introducing VPNs and Public
Key Infrastructure (PKI) and discussing some of the benefits and
challenges of two popular VPN implementations, we'll document how
to build a scalable PKI to simplify VPN authentication
management.
"Two major pieces of FOSS (Free and Open Source Software) for
VPNs are OpenSWAN and OpenVPN. Generally speaking, OpenSWAN is
lighter weight, faster, and largely interoperable with other IPSec
(IP Security) implementations. For example, if you need to connect
to a Cisco or a Linksys, OpenSWAN is recommended..."
