Cisco Systems OL-12172-01 manual An Outside User Attempts to Access an Inside Host, 15-5

Chapter 15 Firewall Mode Overview

Routed Mode Overview

The following steps describe how data moves through the security appliance (see Figure 15-3):

1.A user on the inside network requests a web page from the DMZ web server using the destination address of 10.1.1.3.

2.The security appliance receives the packet and because it is a new session, the security appliance verifies that the packet is allowed according to the terms of the security policy (access lists, filters, AAA).

For multiple context mode, the security appliance first classifies the packet according to either a unique interface or a unique destination address associated with a context; the destination address is associated by matching an address translation in a context. In this case, the interface is unique; the web server IP address does not have a current address translation.

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 15-4shows an outside user attempting to access the inside network.

Figure 15-4 Outside to Inside

www.example.com

Outside

209.165.201.2

10.1.2.110.1.1.1

Inside DMZ

User

10.1.2.27

92407

	Cisco Security Appliance Command Line Configuration Guide
OL-12172-01		15-5