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Chapter 39
Virtual Private Networks (VPN)
Business Communications Manager uses the Internet and tunneling protocols to create secure
extranets. These secure extranets require a protocol for safe transport from the Business
Communications Manager to another device through the Public Data Network (PDN). Business
Communications Manager uses the PPTP
tunneling protocols. Both of these protocols have encryption, but IPSec has a slightly more secure
hashing algorithm for negotiating keys.
Extranets can connect:
•
mobile users to a fixed private network at their office over the PDN
•
private networks in the two branch offices of the same corporation over PDN
•
two divisions of the same corporation over the corporate intranet
When connecting two branch offices, the use of a VPN over the public data network is very
efficient if the connection is required only intermittently or a dedicated point-to-point link is
considered too expensive. Also, with the advent of business-to-business solutions, VPNs can be
deployed to provide secure connections between corporations.
PPTP tunnel notes
PPTP tunnels are used when a mobile user wishes to connect securely to a Business
Communications Manager. PPTP client software is required to use a PPTP tunnel. This client
software is available for all personal computer operating systems from Microsoft. This client is
included in Windows 98.
PPTP tunnels are created from a client to a server or from a server to a server. To form an extranet
using PPTP, a mobile, remote user does the following:
•
Establishes a connection with the public data network's point-of-presence (POP), typically
through an Internet service provider (ISP) using dial up links.
•
After the Internet connection is up, the remote user launches a second connection which is a
VPN tunnel to Business Communications Manager. The Business Communications Manager
public IP address is used to establish the tunnel.
•
On the Business Communications Manager, the user id of the incoming user is enabled for
dial-in access.
("PPTP" on page
754) and IPSec
("IPSec" on page
Programming Operations Guide
753
765)
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