Glossary of terms.

Firewall--A device or application resource that controls access between private trusted networks and public untrusted networks (e.g. Internet), or between sub-networks within a private network (e.g. intranet). Firewalls track and control communications, deciding whether to pass, reject, encrypt or log communications, and ensure that these communications adhere to the defined security policy.

Content Filtering--Evaluating electronic communications, such as e-mail or Web pages, to identify contained key words or phrases, as well as viruses and vandals. User-defined criteria can be set to block or allow this content into the private network. Common usage of this technology is to defend against e-mail viruses or inappropriate Web content.

VPN (Virtual Private Network)--A network with some public segments in which data passing over its public segments is encrypted to achieve secure communications. A VPN is significantly less expensive and more flexible than a dedicated private network.

SSL (Secure Socket Layer)--A protocol combining RSA public key encryption and the services of a Certificate Authority to provide a secure environment for electronic commerce and communications.