Programs to improve authentication and/or to provide encryption. Authentication is a system used to verify the identity of an entity. An example of the use of authentication is a typical login session. Encryption is the method of secure data by making the information unreadable unless the correct key is known. A password file on Unix systems is an example of the use of encryption
A firewall is a combination of software-hardware methods used to provide access control to networks. System designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.