Cisco Catalyst 6500 Series User Manual

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Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide
OL-6392-01
Chapter 9 Configuring Network Address Translation
NAT Overview
Figure 9-6 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.cisco.com from the DNS
server, the DNS server responds with the real local address, 209.165.20.10. Because you want inside
users to use the translated global address for ftp.cisco.com (10.1.2.56) you need to configure DNS reply
modification for the static translation.
Figure 9-7 DNS Reply Modification Using Outside NAT
See the following command for this example:
FWSM/contexta(config)# static (outside,inside) 10.1.2.56 209.165.201.10 netmask
255.255.255.255 dns
ftp.cisco.com
209.165.201.10
DNS Server
FWSM
Outside
Inside
User
10.1.2.27
Static Translation on Inside to:
10.1.2.56
104644
1
2
7
6
5
4
3
DNS Query
ftp.cisco.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
209.165.201.1010.1.2.56
FTP Request
10.1.2.56

Cisco Catalyst 6500 Series Specifications

General

Brand	Cisco
Model	Catalyst 6500 Series
Category	Switch
Language	English