hadoop在Master节点9000端口启动失败原因

由于公司测试需要，需搭建hbase集群，在搭建的过程中，到hadoop安装集群的时候出现了9000端口一直未监听，启动时抛出了以下告警信息：

Starting namenodes on [Master]
Master: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Master: @       WARNING: POSSIBLE DNS SPOOFING DETECTED!          @
Master: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Master: The ECDSA host key for master has changed,
Master: and the key for the corresponding IP address 192.168.40.245
Master: is unknown. This could either mean that
Master: DNS SPOOFING is happening or the IP address for the host
Master: and its host key have changed at the same time.
Master: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Master: @    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
Master: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Master: IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Master: Someone could be eavesdropping on you right now (man-in-the-middle attack)!
Master: It is also possible that a host key has just been changed.
Master: The fingerprint for the ECDSA key sent by the remote host is
Master: cb:7f:7b:bb:12:69:08:92:77:f8:35:64:d5:df:c8:f5.
Master: Please contact your system administrator.
Master: Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Master: Offending ECDSA key in /root/.ssh/known_hosts:4
Master: ECDSA host key for master has changed and you have requested strict checking.
Master: Host key verification failed.

从告警信息可以看出，在/root/.ssh/known_hosts 中IP：192.168.40.245的密钥已经出现变更，这是由于之前这台主机的IP地址有做改变，而之前有做过一次免密钥认证了，所以现在密钥就出现了错乱。

解决办法就是与IP：192.168.40.245这台主机相关的key全部删除，重新再做一次免密钥认证就可以解决问题。