anchor.diff:  
   Successful configuration of the Yubico PAM module to support two factor authentication for OpenVPN has the following prerequisites:
   
  -  * Operating System: Any Unix operating system which supports PAM (Pluggable Authentication Module)
  -    (http://www.kernel.org/pub/linux/libs/pam/)
  -  * Complier : GNU GCC complier (http://gcc.gnu.org/)
  -  * Yubico PAM Module: Yubico PAM Module Version 1.8. (https://developers.yubico.com/yubico-pam/)
  -  * OpenVPN: OpenVPN Version 2.0.9. (http://openvpn.net/index.php/downloads.html)
  -  * FreeRADIUS: FreeRADIUS Version: 1.1.7 or later. (http://freeradius.org/download.html)
  -  * Pam_Radius: pam_radius Version 1.3.17. (ftp://ftp.freeradius.org/pub/radius/pam_radius-1.3.17.tar.gz)
  +Operating System:: 
  +Any Unix operating system which supports 
  +http://www.kernel.org/pub/linux/libs/pam[PAM] (Pluggable Authentication Module)
  +Complier:: http://gcc.gnu.org[GNU GCC complier]
  +https://developers.yubico.com/yubico-pam[Yubico PAM Module]:: Version 1.8
  +http://openvpn.net/index.php/downloads.html[OpenVPN]:: Version 2.0.9.
  +http://freeradius.org/download.html[FreeRADIUS]: Version 1.1.7 or later.
  +Pam_Radius:: ftp://ftp.freeradius.org/pub/radius/pam_radius-1.3.17.tar.gz[Version 1.3.17].
   
   Configuration
   -------------
  
positive.code: -----------------------------------------------------------------------
  
  Append the following line to the beginning of /etc/pam.d/radiusd file:
  ------
     auth required pam_yubico.so id=16 debug authfile=/path/to/mapping/file
  ------
  
  After the above configuration changes, whenever a user connects to the
  server using any RADIUS client, the PAM authentication interface will
  
negative.code: b) Installation of pam_yubico module:
  -------------------------------------
  
  Build instructions for pam_yubico are available in its README.
  
  c) Configuration of pam_yubico module:
  --------------------------------------
  