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Cisco ASA 5500 Series Configuration Guide using ASDM
OL-20339-01
Chapter 5 Configuring the Transparent or Routed Firewall
Firewall Mode Examples
5. When www.example.com responds to the request, the packet goes through the adaptive security
appliance, and because the session is already established, the packet bypasses the many lookups
associated with a new connection. The adaptive security appliance performs NAT by translating the
global destination address to the local user address, 10.1.2.27.
6. The adaptive security appliance forwards the packet to the inside user.
An Outside User Visits a Web Server on the DMZ
Figure 5-3 shows an outside user accessing the DMZ web server.
Figure 5-3 Outside to DMZ
The following steps describe how data moves through the adaptive security appliance (see Figure 5-3):
1. A user on the outside network requests a web page from the DMZ web server using the global
destination address of 209.165.201.3, which is on the outside interface subnet.
2. The adaptive security appliance receives the packet and because it is a new session, the adaptive
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 adaptive 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 classifier
“knows” that the DMZ web server address belongs to a certain context because of the server address
translation.
3. The adaptive security appliance translates the destination address to the local address 10.1.1.3.
Web Server
10.1.1.3
User
209.165.201.2
10.1.1.110.1.2.1
Dest Addr Translation
209.165.201.3
10.1.1.13
Outside
Inside
DMZ
92406
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