Cisco PIX 525 Spezifikationen PDF herunterladen (Seite 193)

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12-7

Cisco Security Appliance Command Line Configuration Guide

OL-6721-01

Chapter 12 Firewall Mode Overview

Routed Mode Overview

3. The security appliance then records that a session is established and forwards the packet out of the

DMZ interface.

4. When the DMZ web server responds to the request, the packet goes through the fast path, which lets

the packet bypass the many lookups associated with a new connection.

5. The security appliance forwards the packet to the inside user.

An Outside User Attempts to Access an Inside Host

Figure 12-5 shows an outside user attempting to access the inside network.

Figure 12-5 Outside to Inside

The following steps describe how data moves through the security appliance (see Figure 12-5):

1. A user on the outside network attempts to reach an inside host (assuming the host has a routable

IP address).

If the inside network uses private addresses, no outside user can reach the inside network without

NAT. The outside user might attempt to reach an inside user by using an existing NAT session.

2. The security appliance receives the packet and because it is a new session, the security appliance

verifies if the packet is allowed according to the security policy (access lists, filters, AAA).

3. The packet is denied, and the security appliance drops the packet and logs the connection attempt.

If the outside user is attempting to attack the inside network, the security appliance employs many

technologies to determine if a packet is valid for an already established session.

www.example.com

User

10.1.2.27

209.165.201.2

10.1.1.110.1.2.1

Outside

Inside DMZ

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