yum -y install pam-devel
tar jxf libpam-google-authenticator-1.0-source.tar.bz2
cd libpam-google-authenticator-1.0
make && make install

[root@chunkserver1 ~]# google-authenticatorDo you want authentication tokens to be time-based (y/n) y
https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=otpauth://totp/root@chunkserver1%3Fsecret%3D4WPHQZ546UTLMBYP
Your new secret key is: 4WPHQZ546UTLMBYP
Your verification code is 856950
Your emergency scratch codes are:
37193134
39632359
18788141
32566498
89776977
#五个码用于在取不到或错的验证码有错时，用于应急用的。不过每个只能用一次，不能重复使用。
Do you want me to update your "/root/.google_authenticator" file (y/n) yDo you want to disallow multiple uses of the same authentication
token? This restricts you to one login about every 30s, but it increases
your chances to notice or even prevent man-in-the-middle attacks (y/n) yBy default, tokens are good for 30 seconds and in order to compensate for
possible time-skew between the client and the server, we allow an extra
token before and after the current time. If you experience problems with poor
time synchronization, you can increase the window from its default
size of 1:30min to about 4min. Do you want to do so (y/n) n
#选择是否开启时间容错。如果客户端设备具有很好的同时间服务器同步功能，建议此处选择n。如果客户端设备（手机、ipad等）不具有很好的同ntp时间同步的功能，可以设为y —— 即开启时间容错。If the computer that you are logging into isn't hardened against brute-force
login attempts, you can enable rate-limiting for the authentication module.
By default, this limits attackers to no more than 3 login attempts every 30s.
Do you want to enable rate-limiting (y/n) y

auth required pam_google_authenticator.so

ChallengeResponseAuthentication no
把上面配置改成
ChallengeResponseAuthentication yes