ZyXEL Communications 1000 Manual De Usuario

Chapter 33 Anti-Virus

ZyWALL USG 1000 User’s Guide

A host-based anti-virus (HAV) scanner is often software installed on computers 
and/or servers in the network. It inspects files for virus patterns as they are 
moved in and out of the hard drive. However, host-based anti-virus scanners 
cannot eliminate all viruses for a number of reasons:

• HAV scanners are slow in stopping virus threats through real-time traffic (such 

as from the Internet). 

• HAV scanners may reduce computing performance as they also share the 

resources (such as CPU time) on the computer for file inspection. 

• You have to update the virus signatures and/or perform virus scans on all 

computers in the network regularly.

A network-based anti-virus (NAV) scanner is often deployed as a dedicated 
security device (such as your ZyWALL) on the network edge. NAV scanners inspect 
real-time data traffic (such as E-mail messages or web) that tends to bypass HAV 
scanners. The following lists some of the benefits of NAV scanners. 

• NAV scanners stops virus threats at the network edge before they enter or exit a 

network. 

• NAV scanners reduce computing loading on computers as the read-time data 

traffic inspection is done on a dedicated security device.