This book describes the underlying principles that crop up again and again in hacker attacks, and then focusses on lessons that can be learned, and on how to protect against recurrence. It is a practical reference book for anyone designing or administering a corporate or eBusiness network which runs across a number of platforms via the Internet. It aims to arm systems administrators with a thorough understanding of the problems of network security and their solutions, and thus help realize the tremendous potential of eBusiness. *practical hands-on advice on securing network systems *security checklists for each scenario *detailed pointers to other detailed information sources *in-depth theoretical background information *Multi-platform coverage *Unique external source of info on IBM systems *Wide use of diagrams and illustrations