17-8
Cisco Security Appliance Command Line Configuration Guide
OL-10088-01
Chapter 17 Applying NAT
NAT Overview
Static PAT
Static PAT is the same as static NAT, except it lets you specify the protocol (TCP or UDP) and port for
the real and mapped addresses.
This feature lets you identify the same mapped address across many different static statements, so long
as the port is different for each statement (you cannot use the same mapped address for multiple static
NAT statements).
For applications that require application inspection for secondary channels (FTP, VoIP, etc.), the security
appliance automatically translates the secondary ports.
For example, if you want to provide a single address for remote users to access FTP, HTTP, and SMTP,
but these are all actually different servers on the real network, you can specify static PAT statements for
each server that uses the same mapped IP address, but different ports (see Figure 17-7).
Figure 17-7 Static PAT
See the following commands for this example:
hostname(config)# static (inside,outside) tcp 209.165.201.3 ftp 10.1.2.27 ftp netmask
255.255.255.255
hostname(config)# static (inside,outside) tcp 209.165.201.3 http 10.1.2.28 http netmask
255.255.255.255
hostname(config)# static (inside,outside) tcp 209.165.201.3 smtp 10.1.2.29 smtp netmask
255.255.255.255
You can also use static PAT to translate a well-known port to a non-standard port or vice versa. For
example, if your inside web servers use port 8080, you can allow outside users to connect to port 80, and
then undo translation to the original port 8080. Similarly, if you want to provide extra security, you can
tell your web users to connect to non-standard port 6785, and then undo translation to port 80.
Host
Outside
Inside
Undo Translation
10.1.2.27209.165.201.3:21
Undo Translation
10.1.2.28209.165.201.3:80
Undo Translation
10.1.2.29209.165.201.3:25
FTP server
10.1.2.27
HTTP server
10.1.2.28
SMTP server
10.1.2.29
130031
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