This book would like to be a type of important computer investment; because it deals with a problem that preoccupies companies requiring a high level of security in particular and whose expected solutions will be taken up in general to a great number of companies that invest and use the intranet and public network for the exchange of information being in company.The information system of today is faced with the problem of security, an area in which many companies are less interested, and therefore we found it appropriate to reflect on an effective prevention of the latter, which will be useful for access to data and the corporate network by internal users (agents) and external users (customers) of the company.