Set up TOTP/Google authenticator on Centos 7

Remember to keep an SSH session open (in a separate terminal) while doing this.

1. yum install google-authenticator
2. google-authenticator
3. follow steps, save backup stuff
4. vim /etc/ssh/sshd_config:
   1. ChallengeResponseAuthentication yes ;
   PermitRootLogin yes ; PasswordAuthentication yes
   
5. vim /etc/pam.d/ssh, add “auth required pam_google_authenticator.so” after the auth line with password.
   

Now you can also set up httpd to use this:

yum install mod_authnz_external.x86_64 ,

(will do this later)