ssh到openwrt时遇到的问题

第一次用ssh登陆openwrt时，一切正常；但我退出后重新登陆时遇到下面的问题：

$ ssh root@192.168.1.1
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS      @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING
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 RSA key sent by the remote host is
42:c1:34:9b:46:23:05:b1:a5:29:54:b7:43:7f:23:ad.
Please contact your system administrator.
Add correct host key in /home/user/.ssh/known_hosts to get rid of this message.
Offending RSA key in /home/user/.ssh/known_hosts:1
  remove with: ssh-keygen -f "/home/user/.ssh/known_hosts" -R 192.168.1.1
RSA host key for 192.168.1.1 has changed and you have requested strict checking.
Host key verification failed.

后来经指点，用 rm -rf ~/.ssh/known_hosts 之后成功登陆。
可能是第一次登陆时ssh留下了记录，所以需删除该文件。