hadoop@master:~$ scp /home/hadoop/.ssh/authorized_keys node3:/home/hadoop/.ssh/
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
a8:68:2e:0e:1e:67:33:db:0f:f8:d0:0b:43:fe:17:e2.
Please contact your system administrator.
Add correct host key in /home/hadoop/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /home/hadoop/.ssh/known_hosts:6
remove with: ssh-keygen -f "/home/hadoop/.ssh/known_hosts" -R node3
ECDSA host key for node3 has changed and you have requested strict checking.
Host key verification failed.
lost connection
出现错误原因：
之前使用ssh登录过该机器，在~/.ssh/known_host中记录了该信息。
解决方案：删除known_host文件中的内容。
hadoop@master:~$ cd .ssh
hadoop@master:~/.ssh$ ls
authorized_keys id_rsa id_rsa.pub known_hosts
hadoop@master:~/.ssh$ sudo vim known_hosts
[sudo] password for hadoop:
hadoop@master:~/.ssh$ scp authorized_keys node1:/home/hadoop/.ssh/
authorized_keys 100% 395 0.4KB/s 00:00
hadoop@master:~/.ssh$ scp authorized_keys node2:/home/hadoop/.ssh/
authorized_keys 100% 395 0.4KB/s 00:00
hadoop@master:~/.ssh$ scp authorized_keys node3:/home/hadoop/.ssh/
hadoop@node3's password:
authorized_keys 100% 395 0.4KB/s 00:00
hadoop@master:~/.ssh$
参考：http://www.cnblogs.com/york-hust/archive/2012/03/27/2420168.html