Hi John, exactly what I was thinking, however I haven't found a way to do that. 
If I ever have time I'll trawl through the code, however I've managed to avoid 
the issue by placing both machines inside the firewall.

Regards
Robin

Sent from my iPhone

On 2 Jul 2013, at 19:48, John Lilley <[email protected]> wrote:

> I don’t know the answer… but if it is possible to make the DNs report a 
> domain-name instead of an IP quad it may help.
> John
>  
>  
> From: Robin East [mailto:[email protected]] 
> Sent: Thursday, June 27, 2013 12:18 AM
> To: [email protected]
> Subject: Re: Exception in createBlockOutputStream - poss firewall issue
>  
> Ok I should have added that external address of the cluster is NATed to the 
> internal address. The internal address yyy.yyy.yyy.yyy is not a routable 
> address for the client. The client can reach the namenode on xxx.xxx.xxx.xxx 
> but I guess the data node must advertise itself using the internal address 
> (yyy.yyy.yyy.yyy). What is the way round this ( not an uncommon problem in 
> secure environments).
>  
> Robin
> 
> Sent from my iPad
> 
> On 27 Jun 2013, at 03:41, Harsh J <[email protected]> wrote:
> 
> Clients will read/write data to the DNs directly. DNs serve on port 50010 and 
> 50020 by default. Please open up these ports, aside of the NN's RPC ports, to 
> be able to read/write data.
>  
> 
> On Thu, Jun 27, 2013 at 2:23 AM, Robin East <[email protected]> wrote:
> I have a single node hadoop cluster setup behind a firewall and am trying to 
> create files using a java program outside the firewall and get the exception 
> below. The java program works fine inside the firewall. The ip address for 
> the single cluster is xxx.xxx.xxx.xxx however it appears that in the 
> createBlockOutputStream the client things the data node is at ip 
> yyy.yyy.yyy.yyy (the internal address of the cluster) which is not accessible.
> The java code looks like this (using hadoop 1.1.2):
> 
>     private static void createHdfsFile() throws IOException {
>         Configuration conf = new Configuration();
>         conf.set("fs.default.name", "hdfs://"+hdfsHost+":9000");
>         FileSystem hdfs = FileSystem.get(conf);
>         System.out.println("HDFS Working Directory: " + 
> hdfs.getWorkingDirectory().toString());
>         FSDataOutputStream os = hdfs.create(new 
> Path("/user/hadoop/test2.txt"));
> 
>         os.writeChars("Example text\n for a hadoop write call\n\ntesting\n");
>         os.close();
>     }
> 
> Any idea how I can get this to work?
> 
> 
> HDFS Working Directory: hdfs://xxx.xxx.xxx.xxx:9000/user/zzzzz
> Jun 26, 2013 8:08:52 PM org.apache.hadoop.hdfs.DFSClient$DFSOutputStream 
> createBlockOutputStream
> INFO: Exception in createBlockOutputStream yyy.yyy.yyy.yyy:50010 
> java.net.ConnectException: Connection timed out: no furth
> er information
> Jun 26, 2013 8:08:52 PM org.apache.hadoop.hdfs.DFSClient$DFSOutputStream 
> nextBlockOutputStream
> INFO: Abandoning block blk_4933973859208379842_1028
> Jun 26, 2013 8:08:53 PM org.apache.hadoop.hdfs.DFSClient$DFSOutputStream 
> nextBlockOutputStream
> INFO: Excluding datanode yyy.yyy.yyy.yyy:50010
> Jun 26, 2013 8:08:53 PM 
> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer run
> WARNING: DataStreamer Exception: org.apache.hadoop.ipc.RemoteException: 
> java.io.IOException: File /user/hadoop/test2.txt
>  could only be replicated to 0 nodes, instead of 1
>         at 
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:1558)
>         at 
> org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:696)
>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>         at 
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
>         at 
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.lang.reflect.Method.invoke(Method.java:601)
>         at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:563)
>         at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1388)
>         at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1384)
>         at java.security.AccessController.doPrivileged(Native Method)
>         at javax.security.auth.Subject.doAs(Subject.java:415)
>         at 
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
>         at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1382)
> 
>         at org.apache.hadoop.ipc.Client.call(Client.java:1107)
>         at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:229)
>         at $Proxy1.addBlock(Unknown Source)
>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>         at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
>         at java.lang.reflect.Method.invoke(Unknown Source)
>         at 
> org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:85)
>         at 
> org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:62)
>         at $Proxy1.addBlock(Unknown Source)
>         at 
> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.locateFollowingBlock(DFSClient.java:3686)
>         at 
> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.nextBlockOutputStream(DFSClient.java:3546)
>         at 
> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.access$2600(DFSClient.java:2749)
>         at 
> org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSClient.java:2989)
> 
> 
> 
>  
> -- 
> Harsh J

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