Mac
SSH
RaspberryPi
raspbian

SSH接続時にエラー

事象

raspiのOSを焼き直したのちに、再度SSHで接続しようとしたところ、以下メッセージがでた。

$ ssh pi@192.168.1.10
Password:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    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
SHA256:/DtVwEQbWOlTXlJx0f5UeZK0BiJtBZcvQmkFMphRUjE.
Please contact your system administrator.
Add correct host key in /var/root/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /var/root/.ssh/known_hosts:1
ECDSA host key for 192.168.1.10 has changed and you have requested strict checking.
Host key verification failed.

対策方法

どうやら、以前のSSH接続時の認証キーが残っていることが原因のようです。

過去の遺物を削除

$ vi /Users/[@ユーザー名]/.ssh/known_hosts 

#known_hostsの中身(一部)
192.168.1.10 ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBNzbWlQ3Y+TfQkWjIyDwWZBCLHZJwuFsIklWLKFUPdumIuGTK9FbrQ1SOEHHO/KoLx9Ta1VgbFoBM8XheSScLk4=

上記known_hostsの部分を削除。

Viの操作方法

操作 コマンド
削除 x
保存 :w
保存せずに閉じる :q!
保存して閉じる :wq

詳しくは viコマンド集

再接続

$ ssh pi@192.168.1.10
The authenticity of host '192.168.1.10 (192.168.1.10)' can't be established.
ECDSA key fingerprint is SHA256:/DtVwEQbWOlTXlJx0f5UeZK0BiJtBZcvQmkFMphRUjE.
Are you sure you want to continue connecting (yes/no)? yes
                                                        ↑で「yes」と入力

Warning: Permanently added '192.168.1.10' (ECDSA) to the list of known hosts.
pi@192.168.1.10's password: 
Linux raspberrypi 4.9.41-v7+ #1023 SMP Tue Aug 8 16:00:15 BST 2017 armv7l

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Fri Dec 29 12:40:23 2017 from 192.168.1.4
pi@raspberrypi:~ $ 

無事ログインできました!

参考

SSHサーバーが変わったら - profaim.jp