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-authenticator

Do 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) y

Do 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) y

By 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