SonicWall integrates Kaspersky into firewalls

SonicWALL, Inc., the leading provider of intelligent network security and data protection solutions, today announced it has expanded its suite of firewall security services with the addition of Kaspersky Anti-Virus to its Enforced Client Anti-Virus and Anti-Spyware solution. SonicWALL® Firewalls ensure easy deployment, provisioning and enforcement of the client on endpoint devices through a unique policy-driven engine.

What is firewall ? - Security Term

A firewall is a set of related programs, located at a network gateway server, that protects the resources of a private network from users from other networks. (The term also implies the security policy that is used with the programs.) An enterprise with an intranet that allows its workers access to the wider Internet installs a firewall to prevent outsiders from accessing its own private data resources and for controlling what outside resources its own users have access to.

Why I need a firewall? - Security Tips and Tricks

You must have a firewall beside your Anti-virus software but why?