Not able to mount via HDFS NFS gateway - hadoop

Question

hadoop version : Hadoop 2.7.1.2.3.2.0-2950
I want to setup a NFS Gateway for the Hadoop cluster we are having. I was following this nicely wrote guide here.
Config
I did all the mentioned steps above, added following configs as mentioned here:
<property>
<name>hadoop.proxyuser.hdfs.groups</name>
<value>*</value>
</property>
<property>
<name>hadoop.proxyuser.hdfs.hosts</name>
<value>*</value>
</property>
<property>
<name>hadoop.proxyuser.root.groups</name>
<value>*</value>
</property>
<property>
<name>hadoop.proxyuser.root.hosts</name>
<value>*</value>
</property>
Setup Validation:
I have restarted data nodes after changing config. When I try from other machine, I get following responses:
saurabh#448140:~$ rpcinfo -p 10.33.37.220
program vers proto port
100005 3 udp 4242 mountd
100005 1 tcp 4242 mountd
100000 2 udp 111 portmapper
100000 2 tcp 111 portmapper
100005 3 tcp 4242 mountd
100005 2 tcp 4242 mountd
100003 3 tcp 2049 nfs
100005 2 udp 4242 mountd
100005 1 udp 4242 mountd
saurabh#448140:~$ sudo showmount -e 10.33.37.220
Export list for 10.33.37.220:
/ *
Error
But still I am getting following error, when trying to mount using this command: sudo mount -v -t nfs -o vers=3,proto=tcp,nolock NFSIP:/ /mountDir:
18/04/04 19:32:48 WARN nfs3.RpcProgramNfs3: Exception
org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.security.authorize.AuthorizationException): User: root is not allowed to impersonate root
at org.apache.hadoop.ipc.Client.call(Client.java:1427)
at org.apache.hadoop.ipc.Client.call(Client.java:1358)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:229)
at com.sun.proxy.$Proxy12.getFileLinkInfo(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileLinkInfo(ClientNamenodeProtocolTranslatorPB.java:784)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:187)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
at com.sun.proxy.$Proxy13.getFileLinkInfo(Unknown Source)
at org.apache.hadoop.hdfs.DFSClient.getFileLinkInfo(DFSClient.java:2156)
at org.apache.hadoop.hdfs.nfs.nfs3.Nfs3Utils.getFileStatus(Nfs3Utils.java:58)
at org.apache.hadoop.hdfs.nfs.nfs3.Nfs3Utils.getFileAttr(Nfs3Utils.java:82)
at org.apache.hadoop.hdfs.nfs.nfs3.RpcProgramNfs3.fsinfo(RpcProgramNfs3.java:1969)
at org.apache.hadoop.hdfs.nfs.nfs3.RpcProgramNfs3.fsinfo(RpcProgramNfs3.java:1925)
at org.apache.hadoop.hdfs.nfs.nfs3.RpcProgramNfs3.handleInternal(RpcProgramNfs3.java:2251)
at org.apache.hadoop.oncrpc.RpcProgram.messageReceived(RpcProgram.java:167)
at org.jboss.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:70)
at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:560)
at org.jboss.netty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendUpstream(DefaultChannelPipeline.java:787)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:281)
at org.apache.hadoop.oncrpc.RpcUtil$RpcMessageParserStage.messageReceived(RpcUtil.java:132)
at org.jboss.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:70)
at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:560)
at org.jboss.netty.channel.DefaultChannelPipeline$DefaultChannelHandlerContext.sendUpstream(DefaultChannelPipeline.java:787)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:296)
at org.jboss.netty.handler.codec.frame.FrameDecoder.unfoldAndFireMessageReceived(FrameDecoder.java:462)
at org.jboss.netty.handler.codec.frame.FrameDecoder.callDecode(FrameDecoder.java:443)
at org.jboss.netty.handler.codec.frame.FrameDecoder.messageReceived(FrameDecoder.java:303)
at org.jboss.netty.channel.SimpleChannelUpstreamHandler.handleUpstream(SimpleChannelUpstreamHandler.java:70)
at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:560)
at org.jboss.netty.channel.DefaultChannelPipeline.sendUpstream(DefaultChannelPipeline.java:555)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:268)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:255)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:255)
at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:88)
at org.jboss.netty.channel.socket.nio.AbstractNioWorker.process(AbstractNioWorker.java:107)
at org.jboss.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:312)
at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:88)
at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:178)
at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
at org.jboss.netty.util.internal.DeadLockProofWorker$1.run(DeadLockProofWorker.java:42)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)