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16-18
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
OL-20748-01
Chapter 16 Configuring NAT
Configuring NAT Control
Figure 16-13
shows a web server and DNS server on the outside. The FWSM has a static translation for
the outside server. In this case, when an inside user requests the address for ftp.example.com from the
DNS server, the DNS server responds with the real address, 209.165.20.10. Because you want inside
users to use the mapped address for ftp.example.com (10.1.2.56) you need to configure DNS reply
modification for the static translation.
Figure 16-13
DNS Reply Modification Using Outside NAT
See the following command for this example:
hostname(config)#
static (outside,inside)
10.1.2.56 209.165.201.10 netmask 255.255.255.255
dns
Configuring NAT Control
NAT control requires that packets traversing from an inside interface to an outside interface match a NAT
rule. See the
“NAT Control” section on page 16-5
for more information.
To enable NAT control, enter the following command:
hostname(config)#
nat-control
To disable NAT control, enter the
no
form of the command.
ftp.example.com
209.165.201.10
DNS Server
Outside
Inside
User
10.1.2.27
Static Translation on Inside to:
10.1.2.56
132924
1
2
7
6
5
4
3
DNS Query
ftp.example.com?
DNS Reply
209.165.201.10
DNS Reply Modification
209.165.201.10
10.1.2.56
DNS Reply
10.1.2.56
FTP Request
209.165.201.10
Dest Addr. Translation
209.165.201.10
10.1.2.56
FTP Request
10.1.2.56
Summary of Contents for 6500 - Catalyst Series 10 Gigabit EN Interface Module Expansion
Page 35: ...P A R T 1 Getting Started and General Information ...
Page 36: ......
Page 297: ...P A R T 2 Configuring the Security Policy ...
Page 298: ......
Page 521: ...P A R T 3 System Administration ...
Page 522: ......
Page 613: ...P A R T 4 Reference ...
Page 614: ......