Re: NAT + Port Forward on Windows XP

"Steve Winograd [MVP]" wrote:

In article <3A85409F-AD08-4B44-82D2-84C4D2AC9AAF@xxxxxxxxxxxxx>,
Vilius <Vilius@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hello,

I have configured NAT on Windows XP box by enabling IPEnableRouter in
registry. Everything worked like a sharm. Now I want to forward some ports to
one host on internal network. I know that I need ICS for that. So I enabled
ICS and forwarded some ports and it worked too. The problem is, that just
after I enabled ICS, NAT doesn't work anymore. My question is how can I make
NAT AND ICS work together?

I'd like to help, but I don't have enough information. Please answer
these questions, and include any other information you can think of
that would help people understand the situation:

1. What indicates to you that ICS breaks NAT? What are you doing that
works when ICS isn't enabled? What's different when you enable ICS?
If there are error messages, what do they say?

2. How many network adapters does the Windows XP box have? What is
each one connected to? What is the IP address and subnet mask of each
one?

OK, my network topology is as follows. I have gateway hardware box with IP
address 10.1.1.1. I configured it to route 192.168.100.121 address through
Windows XP box (which has IP address 10.1.1.225).

Windows XP box has two network interfaces:
First: ip 10.1.1.225, default gw 10.1.1.1, subnet 255.255.255.0
Second: ip 192.168.100.81, subnet 255.255.255.0

When I enable IPEnableRouter in windows xp box, I can ping to
192.168.100.121 (it is a computer on a second network) from other computer on
a network with IP addresses of 10.1.1.x (for example from 10.1.1.121). And
thats fine.

BUT, if I enabled ICS, I can't ping from 10.1.1.121 to 192.168.100.121
anymore.

3. Which network adapter have you told ICS to use as the Internet
connection?

The first one with IP address 10.1.1.225

4. Which network adapter have you told ICS to use as the home network
connection? ICS automatically changes that connection's IP address to
192.168.0.1, with a subnet mask of 255.255.255.0.

Yeah, I know that. But after that I manually changed back second interface
address to 192.168.100.81

I think that you and I use different terminology, and I don't want it
to prevent me from understanding your question. As I see it:

1. The IPEnableRouter registry key enables IP forwarding in Windows
XP. IP forwarding causes packets that arrive at one network interface
to be repeated on other network interfaces, allowing an XP computer to
route traffic between multiple subnets. Is that what you mean by
"NAT".

Yeah, I ment IP forwarding then, not NAT. So I suppose I want IP forwarding
to work between interfaces AND I want to forward couple of ports (for example
10.1.1.225 24868 to 192.168.100.121 4868)
.

Relevant Pages

  • Re: NAT + Port Forward on Windows XP
    ... ICS and forwarded some ports and it worked too. ... How many network adapters does the Windows XP box have? ... The IPEnableRouter registry key enables IP forwarding in Windows ...
    (microsoft.public.windowsxp.network_web)
  • Re: NAT + Port Forward on Windows XP
    ... ICS and forwarded some ports and it worked too. ... after I enabled ICS, NAT doesn't work anymore. ... How many network adapters does the Windows XP box have? ...
    (microsoft.public.windowsxp.network_web)
  • Re: Getting Windows XP To Act as NAT Server
    ... ICS is a Windows XP NAT ROUTER solution - not NAT server. ... solution that would work on a Windows XP host? ...
    (microsoft.public.windowsxp.network_web)
  • Re: NAT + Port Forward on Windows XP
    ... Windows XP box. ... Windows XP box has two network interfaces: ... ICS automatically changes that connection's IP address to ... The IPEnableRouter registry key enables IP forwarding in Windows ...
    (microsoft.public.windowsxp.network_web)
  • Re: Getting Windows XP To Act as NAT Server
    ... ICS is a Windows XP NAT ROUTER solution - not NAT server. ...
    (microsoft.public.windowsxp.network_web)