Remote Desktop and Multiple NIC cards

January 2, 2010 at 08:40:51
Specs: Windows 2003

I have a Windows 2003 server (laptop) in my office. It has 4 NIC cards. One (NIC A) is directly connected to Internet with global static IP address. The other (NIC B) is connected to a router, and it has private static IP address.

This machine can connect Internet through either NIC A or B.

It has a problem on Remote Desktop. NIC A is surely active, but I cannot connect IF NIC B is enabled. When I disabled NIC B, I can connect remotely though NIC A. PING to NIC A is always fine.

Remote Desktop through NIC B is also fine if I am in the same LAN.

I do not understand why I cannot use NIC A for remote desktop from out side network if NIC B is active.

The only difference is that NIC A is PC card (10/100), and NIC B is built-in card on the motherboard (Gigabit).

Can anybody help me?

Thank you.


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#1
January 2, 2010 at 08:49:49

The 2003 server really should be behind the router. It's far more vulnerable with an external IP.

Secondly, windows is not good at controlling multiple NICs. They usually conflict. People insist on using them anyway. Most times they aren't needed.

How do you know when a politician is lying? His mouth is moving.


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#2
January 2, 2010 at 09:03:48

Are both A and B using the same internet provider as in you have one line for internet coming into the office?

If your server hasn't been hit by a port trojan via A it will at any time. Your server is unprotected.

Getting to A or B via the outside depends on two factors;
wan ip address of each
port forwarding/opening port 3389 in the router.

What is the wan ip of each? You can leave off the first couple of octets.


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#3
January 2, 2010 at 09:41:49

Provider ------ [xxx.xxx.251.222] Server 2003
. . . . . .| . . . . . . . . . . . . . . . . . . . .| [192.168.1.3]
. . . . . .| . . . . . . . . . . . . . . . . . . . .|
. . . . . .--[xxx.xxx.251.214] Router --
. . . . . . . . . . . . . . . . . . . . . . . . . . |
. . . . . . . . . . . . . . . . . . . . Workstations [192.168.1.x]

Thank you for your reply. We use Netgear router for client computers. The server I am using is an exception. It is directly connected to the provider. They gave us 10 IP addresses.

In most cases, the server accesses Internet through the router. (I visited "what is your IP" site to check.)

When NIC B (192.168.1.3) is disabled, the server accesses to the Internet directly. The IP is "222".

Anyway, both NICs are always ON. Remote Desktop from worksations (locally) is always fine, but Remote Desktop through NIC A (222) is not reliable. PING is always fine.

So far, I did not receive any attack yet, but I will seriously putting a router or switch between the provider and "222"


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Related Solutions

#4
January 2, 2010 at 12:15:18

In general the problem is that you have to default gateways, one for each NIC.

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#5
January 2, 2010 at 13:58:45

I have another Windows 2003 serer, which also has two NIC and are connected to the Internet in the same way. This machine has no problem to connect remotely. It just has different IP addresses, xxx.xxx.251.217 instead of xxx.xxx.251.222, and 192.168.1.13 instead of 192.168.1.3.

It is true that two NICs have different gateways, one is xxx.xxx.251.209 (NIC A) and the other is 192.168.1.1 (NIC B). But two gateways do not explain why one server is fine and the other is not.

Should I just consider that multiple NICs on Windows 2003 sometimes cause conflict, and Windows server is just something like this?


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#6
January 2, 2010 at 14:14:54

I said that in my first response, that windows is poor at handling multiple NICs. Try removing the default gateway from the internal NIC.

How do you know when a politician is lying? His mouth is moving.


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#7
January 2, 2010 at 14:21:07

If connection is established, comming in to the public NIC and gets forwarded to the internal (private) NIC, the private NIC uses it's default gateway to respond. Can't work !!!

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#8
January 2, 2010 at 16:56:54

It might work when there are 2 internal NICs. I know it works in some scenario.

How do you know when a politician is lying? His mouth is moving.


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