README for ITKACL

ITKACL is an authorization system. It is intended to solve the problem where you have
an identification system (e.g. UNIX passwd files or LDAP) and an authentication system
(e.g. Kerberos) going, but not all valid users are to have access to all systems.

ITKACL is designed to be lightweight and easily integratable into your own systems.
At Studentersamfundet i Trondhjem (the student society of Trondheim), where ITKACL
was developed, we use Kerberos+ITKACL to control access to well over fifty different
services (most of them web-based).

Although the master record for your ACLs is a PostgreSQL database, the core library
does its checking by querying a precomputed user/service database stored in DNS.
This yields a very high degree of infrastructure reuse, enabling very fast
lookups, well-tested replication, and secure integrity checking (through DNSSEC).
ITKACL scales up to at least thousands of users and hundreds of different ACLs;
probably much further.

The ITKACL distribution is currently a bit raw, since it is extracted from various
software packages written more or less independently over the course of ten years.
However, ITKACL is not complex or very hard to set up. Included is a web interface
for adminstering ACLs, a C library for checking (using libunbound to do the actual
DNS lookups and DNSSEC validation), bindings for several languages (Perl, Python,
PHP), and authorization modules for Apache and PAM. Everything can be built as
Debian packages, or you can go the way of make + make install for each package.

To get started, the first thing you want to do is probably to set up the database
and the web interface; see the itkacl-web-1.0 directory. After that, compile the
core library from itkacl-2.1, and adjust the example /etc/itkacl.conf.
You also want to set up your DNS zone, set up DNS keys for dynamic updating,
and run the DNS sync job (also from itkacl-2.1) for the first time.

After this, you are ready to authorize your services using ITKACL! Here's an example
for how to limit access to a web site in Apache using Kerberos and ITKACL:

  AuthType Kerberos
  KrbAuthRealms SAMFUNDET.NO
  Krb5Keytab /etc/apache2/krb5/amsit.keytab
  AuthName "AMSIT, Serveringsgjengen"
  require itkacl /web/amsit/sg

Remember SSL, so that the password is not sent in clear text.

The PAM module can be used like this (together with pam_unix.so, for instance):

  account required pam_itkacl.so realm='/login/itk-workstations'

The programming interfaces should be pretty self-explanatory. However, do note
that the return values are not the same in every language; for instance, since
scripting languages typically communicate fatal errors through exceptions,
they will typically throw such an exception on an error, instead of just returning
-1. Also, since success in e.g. Perl is typically specified using true instead
of 0, the return value is different from the C convention.

ITKACL is Copyright 2004-2013 Steinar H. Gunderson, and is licensed under the
GNU General Public License, version 2. See the included COPYING file for the
full license text.