Creating a two man login module

Vladimir Grujić Vladimir.Grujic at
Wed Oct 16 20:49:17 CEST 2013

You can use google two factor authentication where each  user provides the token for another paired user. Both of them hold they own passwords and the token is appended to it.


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-----Original message-----
From: "PEOPLES, MICHAEL P" <mp4783 at>
To: "freeradius-devel at" <freeradius-devel at>
Sent: Wed, Oct 16, 2013 18:21:06 GMT+00:00
Subject: Creating a two man login module

I am very new to RADIUS and C, so feel free to point and laugh.

On Red Hat Enterprise Linux 5, I wish to create a login module that would require the “consent” of two users before either could login.

I have already modified the pam_radius module to perform a few of the things I need and I know where to “intercept” the authentication process to control whether it is successful or not.  When authenticating for sudo, the modified code seems to perform most of what I want.  However, my problem is with initial system login.

What I cannot figure out is how to provide a prompt during the initial system login so that the two users can “interact”.  I need to be able to do the following:

  1.  Provide a standard login prompt and accept the users PIN + Token
  2.  Generate and display a random number
  3.  Provide a prompt where that random number can be typed in

My experience with the pam_radius module gives me confidence that I can code the underlying “logic” of the process.  What I can’t figure out is where do I code the prompts?  There are suggestions that it is in one of the “getty” type processes, but I cannot figure it.

Any help would be very much appreciated, including the suggestion that what I’m trying to do is either ill-advised (I’m not sure why that would be) or extremely difficult (i.e. requires modifying the core kernel).

Thank you.

Michael Peoples (mp4783)
iGEMS COE, Deployment, Engineering, Application Support and Security
Global Service Assurance, M5
AT&T Business Solutions
Office: +1 614-886-0923
Mobile: +1 614-886-0923

Senior Systems Manager
mpeoples at<mailto:mpeoples at>

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