ZyXEL ZyWALL USG 2000 User Guide - Page 548

Chapter 33 Anti-Virus 33.1.2 What You Need to Know Anti-Virus Engines Subscribe to signature files for ZyXEL's anti-virus engine or one powered by Kaspersky. When using the trial, you can switch from one engine to the other in the Registration screen. After the trial expires, you need to purchase an iCard for the anti-virus engine you want to use and register it in the Registration > Service screen. You must use the ZyXEL anti-virus iCard for the ZyXEL anti-virus engine and the Kaspersky anti-virus iCard for the Kaspersky anti-virus engine. See Chapter 11 on page 265 for details. Virus and Worm A computer virus is a small program designed to corrupt and/or alter the operation of other legitimate programs. A worm is a self-replicating virus that resides in active memory and duplicates itself. The effect of a virus attack varies from doing so little damage that you are unaware your computer is infected to wiping out the entire contents of a hard drive to rendering your computer inoperable. ZyWALL Anti-Virus Scanner The ZyWALL has a built-in signature database. Setting up the ZyWALL between your local network and the Internet allows the ZyWALL to scan files transmitting through the enabled interfaces into your network. As a network-based anti-virus scanner, the ZyWALL helps stop threats at the network edge before they reach the local host computers. You can set the ZyWALL to examine files received through the following protocols: • FTP (File Transfer Protocol) • HTTP (Hyper Text Transfer Protocol) • SMTP (Simple Mail Transfer Protocol) • POP3 (Post Office Protocol version 3) • IMAP4 (Internet Message Access Protocol version 4) How the ZyWALL Anti-Virus Scanner Works The following describes the virus scanning process on the ZyWALL. 1 The ZyWALL first identifies SMTP, POP3, IMAP4, HTTP and FTP packets through standard ports. 548 ZyWALL USG 2000 User's Guide