Hi Igor,

Amazon offers a service where you can have a VPN gateway on your network that leads directly back to the network where youre instances are at.  So that 10.123.x.x subnet would be connected off of the VPN gateway on your network and you'd set up your routers/routing to push traffic for that subnet at the gateway.  

On Thu, Aug 23, 2012 at 12:34 PM, igor Finkelshteyn <iefinkel@gmail.com> wrote:
I'm currently setting up a Hadoop cluster on EC2, and everything works just fine when accessing the cluster from inside EC2, but as soon as I try to do something like upload a file from an external client, I get timeout errors like:

12/08/23 12:06:16 ERROR hdfs.DFSClient: Failed to close file /user/some_file._COPYING_
java.net.SocketTimeoutException: 65000 millis timeout while waiting for channel to be ready for connect. ch : java.nio.channels.SocketChannel[connection-pending remote=/10.123.x.x:50010]

What's clearly happening is my NameNode is resolving my DataNode's IPs to their internal EC2 values instead of their external values, and then sending along the internal IP to my external client, which is obviously unable to reach those. I'm thinking this must be a common problem. How do other people deal with it? Is there a way to just force my name node to send along my DataNode's hostname instead of IP, so that the hostname can be resolved properly from whatever box will be sending files?