Real NAT on Windows XP

Follow these steps to have your Windows XP to work as a NAT but without the restrictions of ICS (Internet

Connection Sharing)

Requirements:

1. To have two network cards:

1. NIC1: One connected to the internal network (any network not only 192.168.1.0).

2. NIC2: The other one connected to the Internet (or other network you want to connect to)

2. To have administrative access to stop/start some services.

Steps:

1. Disable ICS on both NICs.

1. Right-click on NIC -> Properties -> Advanced. Make sure Allow other network users to

connect through this computers Internet connection is unchecked.

2. Enable Routing and Remote Access Service.

1. Control Panel -> Administrative Tools -> Services. Enable Routing and Remote Access

3. Disable Firewall/ICS Service (which might take precedence over step 1)

1. Control Panel -> Administrative Tools -> Services. Disable Windows Firewall/Internet

Connection Sharing (ICS)

4. Configure the NICs:

1. Only 1 should have a gateway (In my example is NIC2). Disable the gateway on the other

NIC (NIC1)

2. Add the NAT configuration.

- You still need to find out the name of your network cards. Here are presenting them as

NIC1 and NIC2. In reality they could be something like Local Area Connection

type the command netsh

pushd routing ip nat

uninstall

install

set global tcptimeoutmins=1440 udptimeoutmins=1 loglevel=ERROR

add interface name="NIC2" mode=FULL

add interface name="NIC1" mode=PRIVATE

popd

And thats it!. Your users on the private network can go to the internet using NAT, just make sure they can

route their packets through this configured PC.

Enjoy.

Nano.

Note1: This solution was compiled from various sources that were providing me hints about the full solution,

but none of them provided all the steps.

Note2: I am pretty sure the steps can be changed, but I have not tried other ways and this one worked for

me

You can use NETSH to apply the whole NAT configuration simply by importing a file.

netsh -f NATcfg.txt

NATcfg.txt

[code]

# ----------------------------------

# NAT configuration

# ----------------------------------

pushd routing ip nat

uninstall

install

set global tcptimeoutmins=1440 udptimeoutmins=1 loglevel=ERROR

#

#NAT Configuration For Interface Local Area Connection

#

add interface name="NIC2" mode=FULL

#

#NAT Configuration For Interface Local Area Connection 2

#

add interface name="NIC1" mode=PRIVATE

popd

[/code]