setting for RAS

I already install RAS at my NT4.0.
How do I set private IP for dial-in computer?
Do I need VPN? What's that?
For examples I want use as IP and still access Internet.
How to set route table in my RAS server?

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When you establish VPN connection you have a tunnel between two comps. This tunnel ignores all traffic except VPN. If you have no Internet connection on the other side you must go into internet through network card or second modem.
Tim HolmanCommented:
With dial up networking, you can have different IP addressing information for each dial up entry, so you could still dial up to the Internet from home, or you could use the seperate RAS entry to dial up to your work network.
Using Windows NT and Remote Access to Connect Your LAN to the Internet
This section on using Windows NT and RAS to connect your LAN to the
Internet has the following subsections:
 - Overview
 - Requirements
 - Example
 - Step-by-step configuration
Windows NT RAS version 3.5x and later was not specifically designed to
route IP from a large local area network (LAN) over a dial-up link.
However, by correctly configuring both the Windows NT RAS computer acting
as a router, and the other computers on your LAN with the correct TCP/IP
settings, you can use the computer running Windows NT RAS as a simple
router to the Internet. Also, for this to work correctly, your ISP must
add a route for your network to their router (this is explained later).
When you are setting up the Windows NT RAS client, it is very important to
explain to the ISP that you are using this dial-in connection as a router
to connect your LAN to the Internet. One common problem is that the ISP is
simply not aware that there is a LAN attached to the dial-in connection,
and that the ISP needs to add a route on its PPP server/router to send
packets back to your Windows NT RAS client.
Also, if you are given a Class C range of IP addresses by your ISP, and
you want to use those Class C addresses on your LAN, you must either:
 - Get one additional IP address that is not part of that Class C network
   to use on the Windows NT RAS Adapter.
 - Subnet your Class C address. For information on subnetting your Class C
   network, consult a TCP/IP manual or contact your ISP.
The following requirements are necessary for using a Windows NT RAS client
as a dial-up router between your LAN and the Internet. These are described
in detail later in this document.
 - A computer running Windows NT 3.51 (or later) with a high-speed RAS
   adapter (ISDN adapter, modem, and so on), and a network adapter
   connected to your LAN.
 - A Point-to-Point Protocol (PPP) connection to the Internet.
 - A valid block of IP addresses (or subnet) for the clients on your LAN.
   This block of addresses must be different from the subnet that the ISP
   uses for its modems/routers. When you receive the list of valid
   addresses you can use on your LAN, you should also receive information
   on which subnet mask to use for the clients on your LAN.
 - An IP address for the RAS adapter (on the computer running Windows NT)
   that is not part of the block of addresses that you are using on your
 - The ISP must add a route on its router that forwards IP packets
   (destined for your subnet) to your Windows NT RAS client computer.
 - The proper registry entries on the computer running Windows NT acting
   as a router. Correct IP address, subnet mask, default gateway, and DNS
   defined on the LAN clients.
For your computer(s) to be identified on the Internet using names, rather
than IP addresses, you also need a domain name. Your ISP should be able to
assist you in obtaining and registering a domain name.
Below is a diagram of an example using RAS as an Internet router, which is
explained below:
                         | Internet |
                         |----------| IP address of dial-in adapter:
                         |    ISP   |
                         |----------| (ISP uses subnet
                              |        for dial-in clients)
  ISP-provided subnet  |---------------| IP address of dial-up adapter:
  used on LAN:         |     NT RAS    |    | server/router |
                       |---------------| IP address of LAN card
                               | subnet mask
                               |         NO default gateway specified.
                       |                |                |
                  |---------|      |---------|      |---------|
                  | client1 |      | client2 |      | client3 |
                  |---------|      |---------|      |---------|
IP address:
Subnet mask:
Default gateway:
   NOTE: The above addresses are provided as an example only. Use ONLY IP
   addresses that are provided to your by your ISP.
In the above diagram, because we are using a subnet mask,
the IP address is actually the network address for the LAN
itself, and cannot be used as the IP address on any client on the LAN.
Also, the address is the broadcast address for the LAN, and
cannot be used as the IP address on any client on the LAN.
Step-by-Step Configuration:
To configure your Windows NT RAS client and LAN for routing to the
Internet over a dedicated PPP account, perform the following steps.
Suggestion--Print out this article and check each item as you complete
each step:
1. Install the TCP/IP protocol and RAS on the Windows NT computer that
   will act as your router. When configuring the LAN adapter, it is very
   important that its IP address is on a different subnet than the IP
   address that the RAS Adapter is using. This is because Windows NT makes
   routing decisions based on the destination IP address of packets. If
   both adapters have IP addresses on the same subnet, Windows NT has no
   way to determine which adapter to forward the packet to.
   If your ISP only provided a block of IP addresses, such as
   255, then you need to either 1) get one additional IP address from your
   ISP (which is not in the range of the IP addresses that was assigned to
   you) to use for your RAS Client or 2) Subnet your range of addresses.
   For information on subnetting your addresses, consult a TCP/IP manual
   or your ISP.
2. On the Windows NT RAS computer that will route IP packets from the LAN
   to the Internet, add the value DisableOtherSrcPackets to the following
   Registry path, and then set the value to 0.
   WARNING: Using Registry Editor incorrectly can cause serious, system-
   Wide problems that may require you to reinstall Windows NT to correct
   them. Microsoft cannot guarantee that any problems resulting from the
   use of Registry Editor can be solved. Use this tool at your own risk.
   a. Start Registry Editor (Regedt32.exe) and go to the following
      registry key:
   b. From the Edit menu, click Add Value.
   c. Enter the following value:
         Value name: DisableOtherSrcPackets
         Value Type: REG_DWORD
         Range: Boolean (0 or 1)
         Default: 1 (not in Registry)
   d. Exit Registry Editor.
   NOTE: This change to the Windows NT registry requires the computer to
   be restarted to take effect. Do not restart the computer right now,
   though, because there are some additional settings that must be
   What this does: By default, the header of each packet sent by the RAS
   computer over the PPP link uses the IP address of the RAS computer as
   the source. Because the packets that come from LAN clients are not
   originating from the RAS computer, you must set DisableOtherSrcPackets
   to 0 so that the packets will be forwarded over the PPP link.
3. If the subnet you have is on the same logical IP subnet as your service
   provider (which is likely in this scenario), you must also add the
   value PriorityBasedOnSubNetwork to the registry of the RAS computer
   that routes packets from the LAN to the Internet, and set this
   parameter to 1.
   A computer can connect to the LAN using a network card and a RAS
   connection. If the RAS connection and the LAN network adapter are
   assigned addresses with the same network number and the Use Default
   Gateway On Remote Network check box is selected, all packets are sent
   over the RAS connection, even though the two addresses are in different
   subnetworks within the same network.
   For example, if the network adapter card has IP address
   (subnet mask and the RAS connection is assigned the
   address, RAS sends all 17.x.x.x packets using the RAS
   connection. If the parameter is set, RAS sends 17.2.x.x packets using
   the RAS connection and 17.1.x.x packets using the network adapter.
   a. Start Registry Editor (Regedt32.exe) and go to the following subkey:
   b. From the Edit menu, click Add Value.
   c. Enter the following value:
         Value Name: PriorityBasedOnSubNetwork
         Value Type: REG_DWORD
         Range: Boolean (0 or 1)
         Default: 0 (not in registry)
   d. Exit Registry Editor.
   NOTE: This change to the Windows NT registry requires the computer to
   be restarted to take effect. Again, do not restart yet as there is
   still one more change to make on the Windows NT RAS computer.
   For additional information on the PriorityBasedOnSubNetwork registry
   entry, see the following article in the Microsoft Knowledge Base:
      ARTICLE-ID: Q143168
      TITLE     : Routing IP Packets to Network Adapter Rather than RAS
4. Enable IP routing on the Windows NT RAS computer. If the computer
   running Windows NT is using version 3.51, go to the Network Control
   Panel, click the TCP/IP Properties, click the Advanced button, and
   select the Enable IP Routing check box. If you are using Windows NT
   4.0, go to the Network Control Panel, click the TCP/IP Properties,
   click the Routing tab, and select the Enable IP Forwarding check box.
   Click OK until you are prompted to restart the Windows NT RAS computer.
   After you restart, this setting (and the above registry changes) will
   take effect.
5. Ensure that your ISP has created a route on the ISP router that
   forwards IP packets that are destined for your subnet (that you are
   using on your LAN) to your Windows NT RAS computer. In the example
   above, the ISP would create a route that forwards all packets for the subnet (the subnet in use on the LAN) to the IP address on the Windows NT server. Without this entry,
   the clients on the LAN will be able to send packets to the Internet,
   but any replies to those packets will not know how to get back to the
6. Install TCP/IP on all the computers on the LAN (that need to get to the
   Internet). Each computer on the Internet requires a unique IP address.
   It is very important to use "real" IP addresses when connecting to the
   Internet, not randomly assigned addresses. Your ISP will provide you
   with IP addresses to use on your computers.
   TIP: One easy way to ensure that you do not have IP address conflicts
   on your LAN is to install the Microsoft Dynamic Host Configuration
   Protocol (DHCP) service on your computer running Windows NT Server.
   DHCP enables the network administrator to create a pool of addresses
   that the clients on the LAN lease from the server. This provides
   several benefits:
    - Prevents the network administrator from having to enter the IP
      address, subnet mask, default gateway, and so on for each user's
      computer when installing TCP/IP. Just install TCP/IP, configure
      it to use DHCP, and restart. This prevents two of the most common
      TCP/IP configuration problems: using an incorrect subnet mask or
      using an incorrect IP address.
    - Reduces possibility of having duplicate IP address conflicts. This
      is also another very common TCP/IP configuration problem.
    - Allows the network administrator to change settings (such as DNS
      server address) without having to go to each user's computer.
    - If we were configuring a DHCP server in the example above, a scope
      would be created that offers the addresses from to
   For additional information about DHCP, see the following articles in
   the Microsoft Knowledge Base:
      ARTICLE-ID: Q169289
      TITLE     : DHCP (Dynamic Host Configuration Protocol) Basics
      ARTICLE-ID: Q139904
      TITLE     : How To Configure Your DHCP Server Scope
   A white paper on DHCP and WINS Implementation, Architecture and
   Planning is available at:
7. Configure the default gateway of the computers on the LAN (that are
   using TCP/IP) so that their default gateway is the IP address of the
   LAN adapter on the computer running Windows NT Server. A default
   gateway is an IP address (which is a router of some type; in this case,
   the computer running Windows NT) where a clients sends packets that
   have a destination which is not on their local network.
   The default gateway is configured as one of the settings for the TCP/IP
   protocol. The location of this setting varies depending on operating
   system and TCP/IP stack. For example, on a computer running Windows 95,
   the default gateway is configured in the Network Control Panel, in the
   TCP/IP Properties.
   The default gateway for the computer running Windows NT (acting as the
   router to the Internet) should be left blank. Refer to the diagram
   above to determine the correct assignment pattern of IP addresses,
   subnet masks, and default gateways.
8. Configure a Domain Name Service (DNS) server address on the computers
   on the LAN. A DNS provides host name to IP address mapping. For
   example, if you wanted to visit the Microsoft Web site, you would enter instead of Check with
   your ISP to find out the IP address of the DNS server address to use
   for your clients. If you are using Windows NT 4.0, you can install the
   DNS server in the Network Control Panel.
   For information on the DNS server in Windows NT 4.0, see the following
   Web page:
9. Dial into the ISP from the Windows NT RAS client.
10. Now your computer running Windows NT should be acting as a router
   between your LAN and the Internet. You can test the configuration by
   attempting to communicate with a computer on the Internet from the RAS
   client, and from a client on your LAN. One easy way to do this is to
   type "ping" at a command prompt.


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