The software described in this documentation is either in Extended Support or Sustaining Support. See https://www.oracle.com/us/support/library/enterprise-linux-support-policies-069172.pdf for more information.
Oracle recommends that you upgrade the software described by this documentation as soon as possible.
By default, each time you use the OpenSSH utilities to connect to
a remote system, you must provide your user name and password to
the remote system. When you connect to an OpenSSH server for the
first time, the OpenSSH client prompts you to confirm that you are
connected to the correct system. In the following example, the
ssh command is used to connect to the remote
host host04:
$ssh host04The authenticity of host ‘host04 (192.0.2.104)’ can’t be established. RSA key fingerprint is 65:ad:38:b2:8a:6c:69:f4:83:dd:3f:8f:ba:b4:85:c7. Are you sure you want to continue connecting (yes/no)?yesWarning: Permanently added ‘host04,192.0.2.104’ (RSA) to the list of known hosts.
When you enter yes to accept the connection
to the server, the client adds the server’s public host key to
the your ~/.ssh/known_hosts file. When you next
connect to the remote server, the client compares the key in this
file to the one that the server supplies. If the keys do not
match, you see a warning such as the following:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: POSSIBLE DNS SPOOFING DETECTED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ The RSA host key forhosthas changed, and the key for the according IP addressIP_addressis unchanged. This could either mean that DNS SPOOFING is happening or the IP address for the host and its host key have changed at the same time. Offending key for IP in /home/user/.ssh/known_hosts:10 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ 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 the RSA host key has just been changed. The fingerprint for the RSA key sent by the remote host isfingerprintPlease contact your system administrator. Add correct host key in /home/user/.ssh/known_hosts to get rid of this message. Offending key in /home/user/.ssh/known_hosts:53 RSA host key forhosthas changed and you have requested strict checking. Host key verification failed.
Unless there is a reason for the remote server’s host key to have changed, such as an upgrade of either the SSH software or the server, you should not try to connect to that machine until you have contacted its administrator about the situation.