Packet Flow - ZyXEL Communications ZYWALL USG 2000 Manual

Unified security gateway

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Anti-Virus Scanner

With the anti-virus packet scanner, your ZyWALL scans files transmitting through

the enabled interfaces into the network. The ZyWALL helps stop threats at the

network edge before they reach the local host computers.

The anti-spam feature can mark or discard spam. Use the white list to identify

legitimate e-mail. Use the black list to identify spam e-mail. The ZyWALL can also

check e-mail against a DNS black list (DNSBL) of IP addresses of servers that are

suspected of being used by spammers.

Application Patrol

Application patrol (App. Patrol) manages instant messenger (IM), peer-to-peer

(P2P) applications like MSN and BitTorrent. You can even control the use of a

particular application's individual features (like text messaging, voice, video

conferencing, and file transfers). Application patrol has powerful bandwidth

management including traffic prioritization to enhance the performance of delay-

sensitive applications like voice and video. You can also use an option that gives

SIP priority over all other traffic. This maximizes SIP traffic throughput for

improved VoIP call sound quality.

2.2 Packet Flow

This section lists the order in which the ZyWALL applies its features and checks.

The following is the key used to describe the packet flow in the ZyWALL.

Table 4 Packet Flow Key

ZyWALL USG 2000 User's Guide

The interface on which the packet is received or sent

The PPPoE or PPTP encapsulation used

Application Layer Gateway

Destination NAT

Routing includes policy routes, interface routing, static routes and load

balancing for example.

Firewall (Through ZyWALL)

Firewall (To ZyWALL)

Intrusion Detection and Protection

Chapter 2 Features and Applications