安装方式一：
Liunx

yum -y install epel-release
yum -y install google-authenticator

ubuntu

sudo apt update
sudo add-apt-repository universe
sudo apt install libpam-google-authenticator

安装方式二：
Liunx

yum install -y git make gcc libtool pam-devel qrencode ntpdate
git clone https://github.com/google/google-authenticator-libpam.git
cd   google-authenticator-libpam/
./bootstrap.sh
./configure
make
make install

ubuntu

sudo apt-get  -y install autoconf  git make gcc libtool libpam0g-dev qrencode ntpdate
git clone https://github.com/google/google-authenticator-libpam.git
cd   google-authenticator-libpam/
./bootstrap.sh
./configure
sudo make
sudo make install

配置ssh

vim /etc/ssh/sshd_config    #ubuntu   sudo

修改如下的配置项：

ChallengeResponseAuthentication yes
UsePAM yes

配置PAM

vim /etc/pam.d/sshd      #ubuntu   sudo

Liunx

#%PAM-1.0
auth      required     pam_google_authenticator.so   #添加至第一行

ubuntu

auth      required      pam_google_authenticator.so       #末尾添加

重启ssh

systemctl restart sshd     #ubuntu   sudo

配置google authenticator
首要条件：先切换到你需要设置的帐号 

google-authenticator
Do you want authentication tokens to be time-based (y/n)  #基于时间生成身份验证
#已经安装qrencode会产生一个二维码，二维码连接也可以URL显示
Your new secret key is ：***********   # 密钥key
Your verification code is : #code 动态码
Your emergency scratch codes are:  #  生成5 个紧急救助码
Do you want me to update your "/root/.google_authenticator" file? (y/n)  #一直确认下去
# 生成了一个 .google_authenticator 文件

your chances to notice or even prevent man-in-the-middle attacks (y/n)  #一直确认下去
Do you want to do so? (y/n)   #一直确认下去
Do you want to enable rate-limiting? (y/n)  #设置完成

#上面的意思大概为：禁止多次使用相同的身份验证，限制每30秒登录一次，移动端每30秒更新一次，移动端和客户端时间误差30秒，30秒内不能超过3次登录。

如果需要删除一个用户的Google验证，删除这个用户下产生的home/.google_authenticator文件即可