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Virtual Private Networks (VPN / PPTP)
The Internet has evolved in the
last year to one of the main issues in networking:
Most people use it to "surf":
to view WWW-webpages in HTML-format.
But the Internet has also its security problems, because any
information transmitted from your system (like:
your credit-card number , you enter on making an online
purchase), is transmitted via several
stages to the destination server, and somebody could listen in to
that transmission:

That problem was solved by introducing SHTTP
(Secure Hyper Text ) in addition to the standard
HTTP-protocol.
Now the worldwide availability of the Internet becomes more and
more interesting for companies for internal use:
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have the "road warriors"
(salesmen, service technician,..) connect to the
home office via Internet (instead
of making expensive long distance,
sometimes intercontinental, phone calls)

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connect branch offices in different
locations (countries, continents)
via Internet (instead via
expensive leased lines, like: Frame-relay)
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It is very easy to setup a Windows system (95 / 98 / NT4) to share a drive via the Internet, but again, it leaves a security problem:

unauthorized people (usually called hackers) try to
break in (not everybody has such top
secret information like the US Department of Defense, which have
several hundred such attacks a day, but hackers can do some
damage to any data).
For that reason, companies connecting their network to the
Internet usually try to protect their system by installing a
"Firewall": a filter between the Internet and the company
network.
To allow secure connection via the Internet, several companies
(including Microsoft) agreed on a new protocol:
Point-to-Point
Tunneling Protocol
(PPTP).
PPTP allows to establish via an IP-network (which
is usually the Internet, but can also be a company Intranet) a secure connection by encapsulating inside
the IP-packet an encrypted private protocol, which can be
NetBEUI, IPX or TCP/IP (with a private
IP-address range):

There are several companies offering now devices/support for
PPTP.
Microsoft has implemented PPTP on Windows 95 / 98 / NT4 as:
Virtual Private
Network
(VPN):

Using NetBEUI as example, the above
animation shows:
- the network client passes a request to the protocol layer
- the request is wrapped in a protocol envelope (in this example: NetBEUI)
- the protocol envelope is passed on to the VPN-adapter
- the protocol envelope is wrapped again inside a TCP/IP envelope
- the TCP/IP envelope is transmitted via the Internet
on the receiving system:
- the VPN-adapter opens the TCP/IP envelope.
- the protocol envelope is then opened again.
- the data (the "letter
inside 2 envelopes") is
passed on to its final destination.
You can download detailed
information via a link from:
http://www.microsoft.com/communications/PPTPdownload0.htm on:
Microsoft
Virtual Private Networking
Installation, Configuration, and Using PPTP with
Microsoft Clients and Servers
User and Administration Guide |
it downloads as MSPPTP.EXE
(143 Kbyte), which is self-extracting to a word-file: PPTPInstall5-22.doc
(1.378 KByte) with 34 pages.
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Support for Virtual Private
Networking: |
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available as Client as FREE download
from Microsoft as
part of the Dialup-Networking 1.2 Upgrade |
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included as Client |
NT4 |
included in NT4 Workstation and Server
as Client and Server |
While Windows NT4 Server can handle MULTIPLE
incoming VPN-connections and while Windows NT4 workstation can
handle ONE incoming VPN-connection,
Windows95 and Windows98 can only be VPN-Clients:
able to establish the connection to an NT4 VPN-server, but
not beeing
able to act as a VPN-server, accepting incoming VPN-connections.
Windows95/98 cannot act as
VPN-server
(but Windows95/98 is able to provide simple disk sharing via the
Internet)
- Installation of
the Windows NT4 RAS-Server
- Connection with
Windows NT4 RAS-Server to the Internet
- Installation of
the Windows NT4 RAS-VPN Server
- Allowing
connection to Windows NT4 RAS-VPN Server
- Installation of
the Windows95/98 VPN-Client
- Configure the
Windows95/98 VPN Connection
- Connect from
Windows95/98 to a VPN server
Using a Windows NT4
workstation as a VPN-dialin to a Server network:

- Installating NT4
RAS as VPN-Dialin to a Network
- Windows95/98 as
VPN-Client dialing into a Novell network
Using a Windows NT4 workstation as a TCP/IP-dialin
to a Mainframe:

- NT4 RAS as VPN
TCP/IP - Dialin to a network/mainframe
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