pexpect.pxssh.ExceptionPxssh: Could not establish connection to host

>>> vyos.login()
Traceback (most recent call last):
  File "", line 1, in
  File "build/bdist.linux-x86_64/egg/vymgmt/router.py", line 123, in login
  File "/usr/lib/python2.7/site-packages/pexpect-4.2.1-py2.7.egg/pexpect/pxssh.py", line 297, in login
    raise ExceptionPxssh('Could not establish connection to host')

pexpect.pxssh.ExceptionPxssh: Could not establish connection to host

# ssh [email protected]
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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 RSA key sent by the remote host is
d4:75:fa:fa:93:6a:3e:ac:d9:2c:b7:2a:54:61:ba:ba.
Please contact your system administrator.
Add correct host key in /root/.ssh/known_hosts to get rid of this message.
Offending RSA key in /root/.ssh/known_hosts:64
RSA host key for 192.168.23.131 has changed and you have requested strict checking.
Host key verification failed.

/root/.ssh/known_hosts 中已经存在了原来的IPssh记录，删除即可。