SSH失败Permission Denied (publickey,gssapi-keyex,gssapi-with-mic)，原因是没有使用ed25519
ssh-keygen -t ed25519
$ ls .ssh/
id_ed25519 id_ed25519.pub known_hosts
ssh-copy-id -p 22 root@www.xxx.com
Number of key(s) added: 1
Now try logging into the machine, with: "ssh -p '22' 'root@www.xxx.com'"
and check to make sure that only the key(s) you wanted were added.
#实现免密登录
ssh root@www.xxx.com
#如果报错打印详细信息
ssh -vv root@www.xxx.com
