在配置一臺宿主機兩臺docker容器的hadoop集羣時，已經配置了三臺機器的ssh，但是在啓動hadoop的輔助接點時，報錯如下：
[root@lzj module]# start-dfs.sh
Starting namenodes on [lzj]
lzj: starting namenode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-namenode-lzj.out
172.17.0.2: starting datanode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-datanode-c172b0d0013a.out
172.17.0.3: starting datanode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-datanode-1dadd673bf95.out
192.168.85.137: starting datanode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-datanode-lzj.out
Starting secondary namenodes [hadoop003]
hadoop003: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
hadoop003: @ WARNING: POSSIBLE DNS SPOOFING DETECTED! @
hadoop003: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
hadoop003: The ECDSA host key for hadoop003 has changed,
hadoop003: and the key for the corresponding IP address 172.17.0.3
hadoop003: is unchanged. This could either mean that
hadoop003: DNS SPOOFING is happening or the IP address for the host
hadoop003: and its host key have changed at the same time.
hadoop003: Offending key for IP in /root/.ssh/known_hosts:6
hadoop003: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
hadoop003: @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
hadoop003: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
hadoop003: IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
hadoop003: Someone could be eavesdropping on you right now (man-in-the-middle attack)!
hadoop003: It is also possible that a host key has just been changed.
hadoop003: The fingerprint for the ECDSA key sent by the remote host is
hadoop003: SHA256:cBKAZidz8oLvN9IGKLLQFGJfGD0h0s8yrgRV+flRH1k.
hadoop003: Please contact your system administrator.
hadoop003: Add correct host key in /root/.ssh/known_hosts to get rid of this message.
hadoop003: Offending ECDSA key in /root/.ssh/known_hosts:4
hadoop003: ECDSA host key for hadoop003 has changed and you have requested strict checking.
hadoop003: Host key verification failed.
如上所示，在hadoop啓動輔助接點[hadoop003]，即爲172.17.0.3接點時，報錯POSSIBLE DNS SPOOFING DETECTED!，提示遠程信息修改，未檢測到DNS。
解決辦法
vi /root/.ssh/known_hosts
進入known_hosts文件後，刪除hadoop003的鍵值，然後保存。重新啓動hadoop集羣
[root@lzj module]# start-dfs.sh
Starting namenodes on [lzj]
lzj: starting namenode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-namenode-lzj.out
172.17.0.2: starting datanode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-datanode-c172b0d0013a.out
172.17.0.3: starting datanode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-datanode-1dadd673bf95.out
192.168.85.137: starting datanode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-datanode-lzj.out
Starting secondary namenodes [hadoop003]
The authenticity of host 'hadoop003 (172.17.0.3)' can't be established.
ECDSA key fingerprint is SHA256:cBKAZidz8oLvN9IGKLLQFGJfGD0h0s8yrgRV+flRH1k.
ECDSA key fingerprint is MD5:ff:d1:62:ad:8f:6a:e0:bf:2e:02:5c:18:84:09:c7:86.
Are you sure you want to continue connecting (yes/no)? yes
hadoop003: Warning: Permanently added 'hadoop003' (ECDSA) to the list of known hosts.
hadoop003: starting secondarynamenode, logging to /opt/module/hadoop-2.7.2/logs/hadoop-root-secondarynamenode-1dadd673bf95.out
hadoop集羣啓動成功。