Thinkpads Forum

I can use VPN and then remote desktop connection to connect to my office desktop using home wireless. But I can not connect to it using public Library wireless.

For this public library wireless, I can connect to the network. But I can not have internet until I open the browser to input username and password. Also, VPN is connected successfully. Everything seems to work well.

But when I use remote desktop connection, it tells me the remote computer can not be found. I don't know why.

Can anybody give me some advices?

The remote computer probably has a private IP address on your network as opposed to a public IP. The library computer is probably set up to use a public DNS server which knows nothing about the private IPs on your network.

If you can make changes to the library computer internet settings tell it to use the private DNS server on your network - you should be able to get it from your network folks.

But they will probably freak when they realize that you are connecting to their network as a trusted resource from a (probably) trojan and virus infested public machine. I sure would.

Ed Gibbs

egibbs wrote:The remote computer probably has a private IP address on your network as opposed to a public IP. The library computer is probably set up to use a public DNS server which knows nothing about the private IPs on your network.

If you can make changes to the library computer internet settings tell it to use the private DNS server on your network - you should be able to get it from your network folks.

But they will probably freak when they realize that you are connecting to their network as a trusted resource from a (probably) trojan and virus infested public machine. I sure would.

Ed Gibbs

Hi Ed

I was not using library computer. I use my X61 Tablet but through their wireless network. I am afraid the same situation happens if I use airport wireless??Thanks

According to wikipedia:
http://en.wikipedia.org/wiki/Remote_Desktop_Protocol
RDP uses TCP port 3389. If the public library wireless network use transparent proxy then you can only do web browsing(port 80, 443) and nothing else.

(Of course there is always something else.)

teetee wrote:RDP uses TCP port 3389. If the public library wireless network use transparent proxy then you can only do web browsing(port 80, 443) and nothing else.

I was thinking this as well, but this argument kind of crumbles when you consider that the original poster was able to open a VPN to his office.

Hmmm... Strange.

Are you absolutely, 100% sure that the RDP is going through the VPN tunnel and not around it? That's the only thing that comes to mind.

Ed Gibbs

VPN client typically uses UDP port to communicate with the server. My guess is if the library network uses transparent proxy then it is either configured to allow VPN through (TCP) or vpn client simply uses UDP to communicate with the server. All the other TCP traffic (except port 80,443) are blocked.