Orthrus is a C library and user interfaces for RFC 2289, 
"A One-Time Password System (OTP)", also known as OPIE or S/Key. 

-= Building =-
Orthrus uses scons to build.  For most people, just run:
   # scons
   # scons install
And Orthrus will be installed into /usr/local.

Ensure using Python 2 currently, so you might need to
    # python /usr/bin scons
    # python /usr/bin scons install

To change where things are installed, or what APR is used, create a build.py,
with something like this:

APR="/usr/bin/apr-1-config"
APRUTIL="/usr/bin/apu-1-config"
PREFIX="/opt/othrus"