Watchguard Firebox X1000 Betriebsanweisung PDF herunterladen (Seite 127)

User Guide 111

CHAPTER 9 Configuring Proxied Services

Proxy filtering goes a step beyond packet filtering by examining a

packet’s content, not just the packet’s header. Consequently, the proxy

determines whether a forbidden content type is hidden or embedded in

the data payload. For example, an email proxy examines all SMTP packets

to determine whether they contain forbidden content types, such as

executable programs or items written in scripting languages. Such items

are common methods of transmitting computer viruses. The SMTP proxy

knows these content types are not allowed, while a packet filter would not

detect the unauthorized content in the packet’s data payload.

Proxies work at the application level, while packet filters work at the

network and transport protocol level. In other words, each packet

processed by a proxy is stripped of all network wrapping, analyzed,

rewrapped, and forwarded to the intended destination. This adds several

layers of complexity and processing beyond the packet filtering process.

What this means, of course, is that proxies use more processing

bandwidth than packet filters. On the other hand, they catch dangerous

content types in ways that packet filters cannot.

To add or configure a proxied service, use the procedures for filtered

services in the previous chapter, “Configuring Filtered Services.” For

more information on proxies, see the following collection of FAQs:

https://support.watchguard.com/advancedfaqs/proxy_main.asp

1 2 ... 122 123 124 125 126 127 128 129 130 131 132 ... 270 271

Keine Kommentare

Watchguard Firebox X1000 Betriebsanweisung Seite 127