Static Pat - Cisco PIX 500 Series Configuration Manual

Chapter 17 Configuring NAT
NAT Overview
The main difference between dynamic NAT and a range of addresses for static NAT is that static NAT
allows a remote host to initiate a connection to a translated host (if an access list exists that allows it),
while dynamic NAT does not. You also need an equal number of mapped addresses as real addresses with
static NAT.

Static PAT

Static PAT is the same as static NAT, except that 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, provided
the port is different for each statement. You cannot use the same mapped address for multiple static NAT
statements.
For applications that require inspection for secondary channels (for example, FTP and VoIP), 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 17-8).
Figure 17-8 Static PAT
Host
Outside
Undo Translation
209.165.201.3:21 10.1.2.27
Undo Translation
209.165.201.3:25 10.1.2.29
Undo Translation
209.165.201.3:80 10.1.2.28
Inside
FTP server SMTP server
10.1.2.27 10.1.2.29
HTTP server
10.1.2.28
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
Cisco Security Appliance Command Line Configuration Guide
17-9
OL-12172-03