问题：
2016-09-05 16:40:03,320 FATAL org.apache.hadoop.hdfs.server.namenode.NameNode: Exception in namenode join
java.net.BindException: Problem binding to [master:9000] java.net.BindException: Cannot assign requested address; For more details see: http://wiki.apache.org/hadoop/BindException
at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:719)
at org.apache.hadoop.ipc.Server.bind(Server.java:419)
at org.apache.hadoop.ipc.Server$Listener.(Server.java:561)
at org.apache.hadoop.ipc.Server.(Server.java:2166)
at org.apache.hadoop.ipc.RPC$Server.(RPC.java:897)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Server.(ProtobufRpcEngine.java:505)
at org.apache.hadoop.ipc.ProtobufRpcEngine.getServer(ProtobufRpcEngine.java:480)
at org.apache.hadoop.ipc.RPC$Builder.build(RPC.java:742)
at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.(NameNodeRpcServer.java:311)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createRpcServer(NameNode.java:614)
at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:587)
at org.apache.hadoop.hdfs.server.namenode.NameNode.(NameNode.java:751)
at org.apache.hadoop.hdfs.server.namenode.NameNode.(NameNode.java:735)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1407)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1473)
采用的是云服务搭建的集群，用的是公网地址。
ifconfig后出现：
eth0 Link encap:Ethernet HWaddr 52:54:00:C6:39:03
inet addr:10.141.88.213 Bcast:10.141.127.255 Mask:255.255.192.0
但我的hosts是：
127.0.0.1 localhost localhost.localdomain
123.207.161.186 master
123.207.145.16 slave1
123.207.140.169 slave2
如果配置私网地址，主机之间ping不通。
