Configure a PPTP server behind SUA

- Introduction

PPTP is a tunneling protocol defined by the PPTP forum that allows PPP packets to be encapsulated within Internet Protocol (IP) packets and forwarded over any IP network, including the Internet itself.

In order to run the Windows XP PPTP client, you must be able to establish an IP connection with a tunnel server such as the Windows NT Server 4.0 Remote Access Server.

Windows Dial-Up Networking uses the Internet standard Point-to-Point (PPP) to provide a secure, optimized multiple-protocol network connection over dial-up telephone lines. All data sent over this connection can be encrypted and compressed, and multiple network level protocols (TCP/IP, NetBEUI and IPX) can be run correctly. Windows NT Domain Login level security is preserved even across the Internet.

Window XP PPTP Client / Internet / NT RAS Server Protocol Stack

PPTP appears as new modem type (Virtual Private Networking Adapter) that can be selected when setting up a connection in the Dial-Up Networking folder. The VPN Adapter type does not appear elsewhere in the system. Since PPTP encapsulates its data stream in the PPP protocol, the VPN requires a second dial-up adapter. This second dial-up adapter for VPN is added during the installation phase of the Upgrade in addition to the first dial-up adapter that provides PPP support for the analog or ISDN modem.

The PPTP is supported in Windows NT and Windows XP already. For Windows XP, it needs to be upgraded by the Dial-Up Networking 1.2 upgrade.

- Configuration

This application note explains how to establish a PPTP connection with a remote private network in the P334U/P335U SUA case. In ZyNOS, all PPTP packets can be forwarded to the internal PPTP Server (WinNT server) behind SUA. The port number of the PPTP has to be entered in the SMT Menu 15 for P334U/P335U to forward to the appropriate private IP address of Windows NT server.

- Example

The following example shows how to dial to an ISP via the P334U/P335U and then establish a tunnel to a private network. There will be three items that you need to set up for PPTP application, these are PPTP server (WinNT), PPTP client (Win XP) and the P334U/P335U.

- PPTP server setup (WinNT)

- Add the VPN service from Control Panel>Network
- Add an user account for PPTP logged on user
- Enable RAS port
- Select the network protocols from RAS such as IPX, TCP/IP NetBEUI
- Set the Internet gateway to P334U/P335U

- PPTP client setup (Win XP)

- Add one VPN connection from Dial-Up Networking by entering the correct username & password and the IP address of the P334U/P335U's Internet IP address for logging to NT RAS server.
- Set the Internet gateway to the router that is connecting to ISP

- P334U/P335U router setup

- Before making a VPN connection from XP to WinNT server, you need to connect P334U/P335U router to your ISP first.
- Enter the IP address of the PPTP server (WinNT server) and the port number for PPTP as shown below.

`Menu 15 - SUA Server Setup` `Port # IP Address` `------ ---------------` `1.Default 0.0.0.0` `2. 1723 192.168.1.10` `3. 0 0.0.0.0` `4. 0 0.0.0.0` `5. 0 0.0.0.0` `6. 0 0.0.0.0` `7. 0 0.0.0.0` `8. 0 0.0.0.0` `9. 0 0.0.0.0`

When you have finished the above settings, you can ping to the remote Win XP client from WinNT. This ping command is used to demonstrate that remote the WIN XPcan be reached across the Internet. If the Internet connection between two LANs is achieved, you can place a VPN call from the remote Win XP client.

For example:

C:\ping 203.66.113.2

When a dial-up connection to ISP is established, a default gateway is assigned to the router traffic through that connection. Therefore, the output below shows the default gateway of the WIN XP client after the dial-up connection has been established.

Before making a VPN connection from the WIN XPclient to the NT server, you need to know the exact Internet IP address that the ISP assigns to P334U/P335U router in SUA mode and enter this IP address in the VPN dial-up dialog box. You can check this Internet IP address from PNC Monitor or SMT Menu 24.1. If the Internet IP address is a fixed IP address provided by ISP in SUA mode, then you can always use this IP address for reaching the VPN server.

In the following example, the IP address '140.113.1.225' is dynamically assigned by ISP. You must enter this IP address in the 'VPN Server' dialog box for reaching the PPTP server. After the VPN link is established, you can start the network protocol application such as IP, IPX and NetBEUI.

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