Electronic+security

Access authorization restricts access to a computer or to a group of users through the use of authentication systems. These systems can protect either the whole computer or individual services, such as a File Transfer Protocol server. There are many methods for identifying and authenticating users, such as:
 * Authorized access**


 * An interactive logon screen** - a login or logon is the process by which individual access to a computer system is controlled by identifying and authenticating the user and referring to credentials presented by the user for example a password or security question.


 * Passwords** - These are secret words or strings of characters that are used for authentication, to prove identity or gain access to a resource.


 * Biometric systems** - Biometrics consist of methods for uniquely recognizing humans based upon one or more physical or behavioral traits. In computer science, in particular, biometrics is used as a form of identity access management and access control.

However there are often **levels of access** when accessing a computer or network. At the highest level, the network manager can install and remove software, access all user areas and change permissions. At lower levels, a group of users may only be able to access particular pieces of software and their files stored in their own areas. Different levels of access help to ensure that the network remains secure and that only licenced software is used on it.

A **firewall** is a device or set of devices designed to permit or deny network transmissions based upon a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass. Many personal computer operating systems include software-based firewalls which come with the computer, for example Windows Firewall, to protect against threats from the public Internet.

A **proxy server** is a server that sits between a client application, such as a Web browser, and a real server. It intercepts all requests to the real server to see if it can fulfil the requests itself. If not, it forwards the request to the real server. Proxy servers have two main purposes: Improve Performance: Proxy servers can dramatically improve performance for groups of users. This is because it saves the results of all requests for a certain amount of time. Filter Requests: Proxy servers can also be used to filter requests. For example, a company might use a proxy server to prevent its employees from accessing a specific set of Web sites.
 * Encryption** is the conversion of data into a form, called a [|c] iphertext, that cannot be easily understood by unauthorized people. Decryption is the process of converting encrypted data back into its original form, so it can be understood. Encryption can be used to protect data "at rest", such as files on computers and storage devices.


 * Transport Layer Security** (**TLS**) and its predecessor, **Secure Sockets Layer** (**SSL**), are cryptographic protocols that provide communication security on the internet. TLS and SSL encrypt the segments of network connections above the Trasnport layer, using asymmetric cryptography for key exchange, symmetric encryption for privacy, and message authentication codes for message integrity.


 * Audit trail** is a sequence of steps supported by proof documenting the real processing of a transaction flow through an organization, a process or a system.