Solved Need help with folder sharing behind router

June 7, 2011 at 18:50:49
Specs: Windows XP

My situation is this:
Computer 1: Win XP laptop, located in China, connected to the internet via a Linksys E2000 router and external DSL modem, have a fixed internal IP address set in the Linksys router.
Computer 2: Win XP laptop, located in Hong Kong, connected to the internet via a Thomson router and external DSL modem, get dynamic internal IP from the router (DHCP).

What I am trying to do is this:
Share a folder on Computer 1 and map it as a network drive on Computer 2.

Problem is:
I shared the folder on Computer 1 and configured port-forwarding in the Linksys router to forward requests to Computer 1's internal IP. However, whatever I am doing in Computer 2 I am unable to "find" the shared folder on Computer 1. I am trying to connect to Computer 1 via its public IP which I found in websites such as, etc.

1. Am I missing something elementary in the concept?
2. Is there a specific port number that has to be forwarded?
3. How can I trace the route of my connection attempt from Computer 2 to Computer 1, in order to see where the request fails? I checked the Linksys's log but its incoming log was empty. How do I know if the problem is in the port-forwarding or elsewhere?
4. Is there any other/better way to achieve what I am trying to do?

Any help will be highly appreciated!

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June 8, 2011 at 21:18:16
✔ Best Answer

1. Yes. Most file sharing ports will be blocked by the ISPs since they are an avenue for abuse. IF they were open, you would need to forward ports 137,138,139, & 445. However, this would mean that ANYONE would be able to access the shares since most are configured to allow guest access at even a read only level. IN ESSENCE, WHAT YOU ARE TRYING TO DO IS NOT SECURE AND SHOULD NOT BE DONE!

2. see my answer for #1.

3. Most likely, empty connection log means it is being actively blocked by the ISP as it should. Also, most routers are set to NOT allow NETBeui traffic from internal to external anyways. (Even if Microsoft-DS port is specifically for NetBeui-over-tcp/ip)

4. The proper way to network 2 machines in 2 remote physical locations is by using a VPN tunnel. IF the routers support it, create a site-to-site VPN tunnel. This will allow the encrypted transfer of information between the two logical subnets. Essentially, the machines will act as if they were connected to the same physical network. If you cannot establish a VPN connection, you could always use a service like Dropbox ( which would allow you to share and synchronize files on remote machines while also allowing the redundancy by backing up the info to the cloud.

Please let me know if you have any other questions or comments.

IT Desktop & Network Consultant - MOS Master Certified, MCP, MCITP - Windows 7, CCNA Certificate Pending, A+, Network +


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June 8, 2011 at 22:00:14
First of all thanks a lot for your detailed and helpful reply!

I indeed figured out that VPN is what I should go with, and actually tried to setup a VPN Server on Computer 1 and a VPN client on Computer 2, both using the built-in WinXP feature. I did it mainly by following the instructions described here: and here:

In the Linksys router at Computer 1's end I configured port forwarding for 1723 and 500 to the internal IP of Computer 1, as well as made sure that VPN Passthrough is enabled for IPSec, PPTP and L2TP.
In addition, since that the Firewall in the router is activated, I disabled the WinXP's Firewall on Computer 1.

In Computer 2's VPN client I gave the external IP address of Computer 1, as shown in

However, for some reason which is still unclear to me, I can't connect.
When I try to connect from the Client it tries for about 15 seconds and then I get:
"Error 800: Unable to establish the VPN connection..."

I just want to add that I didn't change any configuration in the Computer 2's end router. Should I?

Any idea why this VPN connection refuses to work?
Is there a way to trace where the connection fails?

Thanks a lot,

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