修改 sshd-config 文件，把里面的 PasswordAuthentication 和 PermitRootLogin 都改成 Yes

修改 SSH 配置文件 /etc/ssh/sshd_config

vi /etc/ssh/sshd_config

找到 PermitRootLogin 和 PasswordAuthentication

# Authentication:
LoginGraceTime 120
PermitRootLogin yes //默认为no，需要开启root用户访问改为
yesStrictModes yes 
# Change to no to disable tunnelled clear text passwords
PasswordAuthentication yes //默认为no，改为yes开启密码登陆

重启 SSH 服务
Ubuntu/debian 适用

/etc/init.d/ssh restart

Centos 7 适用

systemctl restart sshd.service

sudo sed -i 's/^#\?PermitRootLogin.*/PermitRootLogin yes/g' /etc/ssh/sshd_config;

sudo sed -i 's/^#\?PasswordAuthentication.*/PasswordAuthentication yes/g' /etc/ssh/sshd_config;

sudo service sshd restart