Can XP act as a router without ICS?

[wartonc]

There's a PC running XP pro and connecting the internet through a DSL modem,
its 2nd network adapter (192.168.1.1) links to a private LAN (192.168.1.0)
controlled by a W2K server (192.168.1.2) with its own DHCP and DNS server.
How can the W2K server access the internet?

I set 192.168.1.1 as W2K server's default gateway; and set IPEnableRouter=1
at
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters (is
this necessary?). Each computer can access the other without any problem,
but W2K server still can't access the internet (fails to ping a internet
host IP).


The PC running XP pro must act like a router, but I can't enable the ICS
service on XP pro, beause it will interfere with the DHCP server on the
private LAN. The W2K server can't manage the XP pro ICS's DHCP, that's why
it has its own DHCP.

I believe something wrong at the route tables.

Part of the route table at XP pro is:
Network Destination Netmask Gateway Interface
Metric
0.0.0.0 0.0.0.0 67.71.42.155
67.71.42.155 1
0.0.0.0 0.0.0.0 67.71.42.155
67.71.42.155 1
192.168.1.0 255.255.255.0 192.168.1.1 192.168.1.1
20
192.168.1.1 255.255.255.255 127.0.0.1 127.0.0.1
20
Default Gateway: 67.71.42.155

Part of the route table at W2K server is:
Network Destination Netmask Gateway Interface
Metric
0.0.0.0 0.0.0.0 192.168.1.1
192.168.1.2 1
192.168.1.0 255.255.255.0 192.168.1.2 192.168.1.2
20
192.168.1.2 255.255.255.255 127.0.0.1 127.0.0.1
20
Default Gateway: 192.168.2.1

Please tell me how to figure it out. Much much thanks.

 

[Steve Winograd [MVP]]

There's a PC running XP pro and connecting the internet through a DSL modem,
its 2nd network adapter (192.168.1.1) links to a private LAN (192.168.1.0)
controlled by a W2K server (192.168.1.2) with its own DHCP and DNS server.
How can the W2K server access the internet?

I set 192.168.1.1 as W2K server's default gateway; and set IPEnableRouter=1
at
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters (is
this necessary?). Each computer can access the other without any problem,
but W2K server still can't access the internet (fails to ping a internet
host IP).


The PC running XP pro must act like a router, but I can't enable the ICS
service on XP pro, beause it will interfere with the DHCP server on the
private LAN. The W2K server can't manage the XP pro ICS's DHCP, that's why
it has its own DHCP.

I believe something wrong at the route tables.

Part of the route table at XP pro is:
Network Destination Netmask Gateway Interface
Metric
0.0.0.0 0.0.0.0 67.71.42.155 67.71.42.155 1
0.0.0.0 0.0.0.0 67.71.42.155 67.71.42.155 1
192.168.1.0 255.255.255.0 192.168.1.1 192.168.1.1 20
192.168.1.1 255.255.255.255 127.0.0.1 127.0.0.1 20
Default Gateway: 67.71.42.155

Part of the route table at W2K server is:
Network Destination Netmask Gateway Interface
Metric
0.0.0.0 0.0.0.0 192.168.1.1 192.168.1.2 1
192.168.1.0 255.255.255.0 192.168.1.2 192.168.1.2 20
192.168.1.2 255.255.255.255 127.0.0.1 127.0.0.1 20
Default Gateway: 192.168.2.1

Please tell me how to figure it out. Much much thanks.

Enabling IP routing simply causes XP Pro to repeat all incoming
packets on all network adapters. That isn't sufficient to share an
Internet connection, even if all of the routes and default gateways
are right. Internet sharing also requires a NAT or proxy server.

Why isn't routing alone sufficient? The Internet-connected computer
has a public IP address, and that's the only address on your network
that's visible to the rest of the world. The 192.168.1.x addresses
are private and invisible. There's no way for an Internet server to
send a packet to a 192.168.1.x. address, such as the W2K server.

A NAT program running on XP Pro would:

1. Receive an Internet request from another 192.168.1.x computer.
2. Remember that computer's IP address.
3. Substitute its own public IP address in the request and send it to
the Internet.
4. Receive the reply from the Internet.
5. Replace its public IP address with the private IP address that it
remembered in #2.
6. Send the reply to the other computer.

The best solution is to use the W2K server as the Internet sharing
computer.
--
Best Wishes,
Steve Winograd, MS-MVP (Windows Networking)

Please post any reply as a follow-up message in the news group
for everyone to see. I'm sorry, but I don't answer questions
addressed directly to me in E-mail or news groups.

Microsoft Most Valuable Professional Program
http://mvp.support.microsoft.com