17-11
Cisco Security Appliance Command Line Configuration Guide
OL-12172-03
Chapter 17 Configuring NAT
NAT Overview
Note
Policy NAT does not support time-based ACLs.
For applications that require application inspection for secondary channels (for example, FTP and VoIP),
the policy specified in the policy NAT statement should include the secondary ports. When the ports
cannot be predicted, the policy should specify only the IP addresses for the secondary channel. With this
configuration, the security appliance translates the secondary ports.
Note
All types of NAT support policy NAT, except for NAT exemption. NAT exemption uses an access list to
identify the real addresses, but differs from policy NAT in that the ports are not considered. See the
“Bypassing NAT” section on page 17-30
for other differences. You can accomplish the same result as
NAT exemption using static identity NAT, which does support policy NAT.
Figure 17-9
shows a host on the 10.1.2.0/24 network accessing two different servers. When the host
accesses the server at 209.165.201.11, the real address is translated to 209.165.202.129. When the host
accesses the server at 209.165.200.225, the real address is translated to 209.165.202.130. Consequently,
the host appears to be on the same network as the servers, which can help with routing.
Figure 17-9
Policy NAT with Different Destination Addresses
See the following commands for this example:
hostname(config)#
access-list NET1 permit ip 10.1.2.0 255.255.255.0 209.165.201.0
255.255.255.224
hostname(config)#
access-list NET2 permit ip 10.1.2.0 255.255.255.0 209.165.200.224
255.255.255.224
hostname(config)#
nat (inside) 1 access-list NET1
hostname(config)#
global (outside) 1 209.165.202.129
hostname(config)#
nat (inside) 2 access-list NET2
hostname(config)#
global (outside) 2 209.165.202.130
Server 1
209.165.201.11
Server 2
209.165.200.225
DMZ
Inside
10.1.2.27
10.1.2.0/24
130039
209.165.201.0/27
209.165.200.224/27
Translation
209.165.202.129
10.1.2.27
Translation
209.165.202.130
10.1.2.27
Packet
Dest. Address:
209.165.201.11
Packet
Dest. Address:
209.165.200.225
Содержание 500 Series
Страница 38: ...Contents xxxviii Cisco Security Appliance Command Line Configuration Guide OL 12172 03 ...
Страница 45: ...P A R T 1 Getting Started and General Information ...
Страница 46: ......
Страница 277: ...P A R T 2 Configuring the Firewall ...
Страница 278: ......
Страница 354: ...17 38 Cisco Security Appliance Command Line Configuration Guide OL 12172 03 Chapter 17 Configuring NAT NAT Examples ...
Страница 561: ...P A R T 3 Configuring VPN ...
Страница 562: ......
Страница 891: ...P A R T 4 System Administration ...
Страница 892: ......
Страница 975: ...P A R T 5 Reference ...
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