Bypassing Nat - Cisco 7604 Configuration Manual
Catalyst 6500 series switch and cisco 7600 series router firewall services module configuration guide using the cli
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Chapter 16
Configuring NAT
hostname(config)# static (inside,outside) tcp 10.1.2.14 telnet access-list TELNET
For HTTP traffic initiated from hosts on the 10.1.3.0 network to the FWSM outside interface (10.1.2.14),
you can redirect the traffic to the inside host at 10.1.1.15 by entering:
hostname(config)# access-list HTTP permit tcp host 10.1.1.15 10.1.3.0 255.255.255.0 eq
http
hostname(config)# static (inside,outside) tcp 10.1.2.14 http access-list HTTP
To redirect Telnet traffic from the FWSM outside interface (10.1.2.14) to the inside host at 10.1.1.15,
enter the following command:
hostname(config)# static (inside,outside) tcp 10.1.2.14 telnet 10.1.1.15 telnet netmask
255.255.255.255
If you want to allow the preceding real Telnet server to initiate connections, though, then you need to
provide additional translation. For example, to translate all other types of traffic, enter the following
commands. The original static command provides translation for Telnet to the server, while the nat and
global commands provide PAT for outbound connections from the server.
hostname(config)# static (inside,outside) tcp 10.1.2.14 telnet 10.1.1.15 telnet netmask
255.255.255.255
hostname(config)# nat (inside) 1 10.1.1.15 255.255.255.255
hostname(config)# global (outside) 1 10.1.2.14
If you also have a separate translation for all inside traffic, and the inside hosts use a different mapped
address from the Telnet server, you can still configure traffic initiated from the Telnet server to use the
same mapped address as the static statement that allows Telnet traffic to the server. You need to create
a more exclusive nat statement just for the Telnet server. Because nat statements are read for the best
match, more exclusive nat statements are matched before general statements. The following example
shows the Telnet static statement, the more exclusive nat statement for initiated traffic from the Telnet
server, and the statement for other inside hosts, which uses a different mapped address.
hostname(config)# static (inside,outside) tcp 10.1.2.14 telnet 10.1.1.15 telnet netmask
255.255.255.255
hostname(config)# nat (inside) 1 10.1.1.15 255.255.255.255
hostname(config)# global (outside) 1 10.1.2.14
hostname(config)# nat (inside) 2 10.1.1.0 255.255.255.0
hostname(config)# global (outside) 2 10.1.2.78
To translate a well-known port (80) to another port (8080), enter the following command:
hostname(config)# static (inside,outside) tcp 10.1.2.45 80 10.1.1.16 8080 netmask
255.255.255.255
Bypassing NAT
This section describes how to bypass NAT. You might want to bypass NAT when you enable NAT control.
You can bypass NAT using identity NAT, static identity NAT, or NAT exemption. See the
NAT when NAT Control is Enabled" section on page 16-10
This section includes the following topics:
•
•
•
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
OL-20748-01
Configuring Identity NAT, page 16-34
Configuring Static Identity NAT, page 16-34
Configuring NAT Exemption, page 16-36
for more information about these methods.
Bypassing NAT
"Bypassing
16-33
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