Cisco ASA 5506-X Configuration Manual page 123

Chapter 5 NAT Examples and Reference
Figure 5-20
3
DNS Reply Modification
209.165.201.10
Procedure
Create a network object for the FTP server.
Step 1
hostname(config)# object network FTP_SERVER
hostname(config-network-object)# host 209.165.201.10
Step 2 Configure static NAT with DNS modification.
hostname(config-network-object)# nat (outside,inside) static 10.1.2.56 dns
DNS64 Reply Modification Using Outside NAT
The following figure shows an FTP server and DNS server on the outside IPv4 network. The ASA has a
static translation for the outside server. In this case, when an inside IPv6 user requests the address for
ftp.cisco.com from the DNS server, the DNS server responds with the real address, 209.165.200.225.
Because you want inside users to use the mapped address for ftp.cisco.com (2001:DB8::D1A5:C8E1)
you need to configure DNS reply modification for the static translation. This example also includes a
static NAT translation for the DNS server, and a PAT rule for the inside IPv6 hosts.
DNS Reply Modification, DNS Server on Host Network
1
DNS Query
ftp.cisco.com?
2
DNS Reply
209.165.201.10
Appliance
10.1.2.56
4
DNS Reply
10.1.2.56
ftp.cisco.com
209.165.201.10
Static Translation on Inside to:
10.1.2.56
DNS Server
Outside
10.1.2.56
Security
FTP Request
Inside
User
10.1.2.27
Cisco ASA Series Firewall CLI Configuration Guide
DNS and NAT
7
FTP Request
209.165.201.10
6
Dest Addr. Translation
209.165.201.10
5
10.1.2.56
5-25