【Linux】密钥ssh登录问题

1.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:yoveAfcUpI5BsNfOMclFleal9FDY/cVlEOwRhSn4Yk8.

Please contact your system administrator.

Add correct host key in /home/zswang/.ssh/known_hosts to get rid of this message.

Offending ECDSA key in /home/zswang/.ssh/known_hosts:1

remove with:

ssh-keygen -f "/home/zswang/.ssh/known_hosts" -R 172.24.4.9

ECDSA host key for 172.24.4.9 has changed and you have requested strict checking.

Host key verification failed.

原因：一台主机上有多个Linux系统，会经常切换，那么这些系统使用同一ip，登录过一次后就会把ssh信息记录在本地的~/.ssh/known_hsots文件中，切换该系统后再用ssh访问这台主机就会出现冲突警告，需要手动删除修改known_hsots里面的内容。

rm -rf ~/.ssh/known_hosts

-----------------------------------------------------------------------------------------------------------------------------------------------------------------

2.Permissions 0664 for './2.pem' are too open.

It is required that your private key files are NOT accessible by others.

This private key will be ignored.

Load key "./2.pem": bad permissions

Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

使用两个ssh工具连接远程服务器，NX和putty，连接的时候偶然发现这个错误，说key文件权限太大，估计是key文件的属性被改的问题；

后来上网查了，把权限改成600即可

chmod  600  /home/xiaoqiang.he/.ssh/*