Authenticate Linux Clients with Active Directory

At a glance...

How authentication works in Windows and Linux
Using Samba and Winbind
Implementation strategies
Walking through the Linux-to-Active Directory integration

http://technet.microsoft.com/en-us/magazine/dd228986.aspx

Systems Administration Toolkit

From IBM DeveloperWorks, an impressive series of articles written by Martin Brown.

Secure programming with the OpenSSL API

Part 1: Overview of the API

Learning how to use the API for OpenSSL -- the best-known open library for secure communication -- can be intimidating, because the documentation is incomplete. Fill in the gaps, and tame the API, with the tips in this article. After setting up a basic connection, see how to use OpenSSL's BIO library to set up both a secured and unsecured connection. And learn a bit about error detection as well.

Part 2: Secure handshake

Securing the handshake during a Secure Sockets Layer session (SSL) is vital, since almost all of the security involving the connection is set up inside the handshake. Learn how to secure the SSL handshake against a man in the middle (MITM) attack -- in which the intruding party masquerades as another, trusted source. This article also introduces the concept of digital certificates and how the OpenSSL API handles them.

Part 3: Providing a secure service

Without secure server applications, the need for secure client applications is nonexistent. With OpenSSL, you can create secure server applications, and although the documentation makes it look intimidating, it's really not difficult.