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VPN Options for
Linux
There is no single standardized VPN tool,
although there are moves toward creating VPN standards. In the meantime,
organizations that want to configure VPNs need to settle on one of several
tools. The three most common tools for Linux are the following: PPTP The Point-to-Point Tunneling Protocol
(PPTP) was developed by a consortium of companies, known collectively as
the PPTP Forum. PPTP is commonly used to link telecommuters or travelers to a
home office. PPTP support ships with recent versions of Windows, so it's easy
to implement on Windows clients. A Linux PPTP server, PoPToP (
available. FreeS/WAN The FreeS/WAN project ( target="_blank">http://www.freeswan.org ) builds on the Internet Key Exchange (IKE) and IPSec protocols to
provide an open source VPN tool for Linux. It's quite popular for
Linux-to-Linux VPNs (one or both ends may host non-Linux computers behind the
VPN router, of course). SSH The Secure Shell (SSH) protocol has the capacity to tunnel other protocols' connections. It's possible to
use this capability to tunnel a PPP connection over an SSH link. Properly
routed, the PPP interfaces on each end of the connection then provide a VPN
between the two sites.This chapter focuses on the first two
approaches. PPTP is a very popular VPN approach, particularly when Windows clients
must connect directly to the VPN router at a central location. There are also
PPTP implementations for many other OSs, and even in dedicated hardware devices
that are frequently referred to as remote access
switches. FreeS/WAN is less popular outside of the Linux world, but it
can be an excellent way to link together multiple networks using Linux
VPN-enabled routers.
