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1. YubiPAM Introduction
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The YubiPAM module provides a simple, easy to configure, way to integrate the
Yubikey into your existing user authentication infrastructure. PAM is used by
GNU/Linux, Solaris and Mac OS X for user authentication.


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2. Status
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  1. Manual add/delete from database. Using the ykpasswd tool you can add
     delete yubikey entries from the database (default: /etc/yubikey).

  2. Per user accounting. Supports indiviudal user account authorisation. This
	 is currently limited to one Yubikey dongle per user account.

  3. Single factor sign in. Currently only single factor (ie. Yubikey OTP) is
	 currently supported. There will be an additional second factor password
	 option added in the near future.
		
  4. Static heuristic support. Heuristic support for OTP data deltas is hard
	 coded. This will be changable in the next release.


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3. Configuration
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Install it in your PAM setup by adding a line to an appropriate file in the
director /etc/pam.d/:

  auth sufficient pam_yubikey.so

and ensure pam_yubikey.so is located in /lib/security/

Supported PAM module parameters are:

  "verbose_otp": enable echoing of the OTP, after all it's only a one time pad.


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4. Utilities
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ykpasswd

The ykpasswd utility provides administration, insert and removal of entries,
for the YubiPAM database. The required elements that need to be entered into
the database include the public UID (fixed modhex portion of an OTP), the AES
key which can be used to decrypt the token, and the private UID which is found
after successful decryption of a valid OTP.

If you have apriori knowledge of these values for user joesmith you can enter
them straight into the command line, using:

# ykpasswd -a -k AESKEY -f PUBLICKEY -p PRIVATEKEY joesmith

Or alteratnively you can just enter the minimum and be prompted to enter the 
information using:

# ykpasswd -a joesmith

If you don't have the private UID it requires you to decrypt a valid token to
get the value. Fortunately you can provide a valid OTP and the appropriate AES
key and let ykpassword determine the public and private UIDs for you, using:

# ykpasswd -a -u joesmith -k AESKEY -o OTP

The "-u" option is an alternative to placing the user name at the end of the
utility which can be cumbersome if you use the Yubikey to generate an OTP and
a carriage return is applied too early :)


ykvalidate

Once a Yubikey has been successfully added to the YubiPAM database, it can be
tested using the ykvalidate tool. Simply pass an OTP associated with the
calling user or specify the actual user and it will confirm if it's VALID or
NOT.

# ykvalidate OTP

# ykvalidate -u joesmith OTP


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5. Troubleshooting
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In the event that the YubiPAM module is not working it may pay to enable debug
mode in order to sort out any issues. To enable debug mode you must reconfigure
the project with the --enable-debug option, for example:

# ./configure --enable-debug

Move the newly generated pam_yubikey.so file to /lib/security, or on a 64-bit
machine to /lib64/security. You'll also have to touch and give appropriate
permissions to the debug output file using:

# touch /var/run/pam-debug.log 
# chmod go+w /var/run/pam-debug.log 

Note: On production systems, debug should NOT be turned on due to its verbosity
and subsequent disclosure of information. As a friendly reminder, the prompt
will indicate that you are in debug mode by indicating "DEBUG MODE!!!". Once 
you've successfully debugged your system reconfigure without the --enable-debug
option and rebuild.