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NAT Configuration Examples
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10.4.1 Dynamic NAT (many to many)
In dynamic (many-to-many) NAT type, multiple source IP addresses in the corporate network will be mapped to multiple NAT
IP addresses (not necessarily of equal number). For a set of local IP address from 10.1.1.1 to 10.1.1.4 there will be a set of
NAT IP address from 60.1.1.1 to 60.1.1.2. In case of many-to-many NAT, only IP address translation takes place, i.e., if a
packet travels from 10.1.1.1 to yahoo.com, Black Box-Firewall only substitutes the source address in the IP header with one of
the NAT IP address and the source port will be the same as the original. If traffic emanates from the same client to any other
server, the same NAT IP address is assigned. The advantage is that the NAT IP addresses are utilized in a better and optimum
manner dynamically.
If a NAT IP address cannot be allocated dynamically at the connection creation time, the packet would be dropped.
Figure 19 Dynamic NAT
The dynamic NAT configuration shown in Figure 19 includes:
Private network addresses:10.1.1.1—10.1.1.4
Public (NAT) IP address range: 60.1.1.1—60.1.1.2
To create NAT pool with type dynamic, specify the IP address and the NAT ending IP address.Then add a policy with the
source IP address range, and attach the NAT pool to the policy.
60.1.1.1-60.1.1.2
OPAL
10.1.1.3
10.1.1.2
10.1.1.1
INTERNET
10.1.1.4
Blackbox/configure> firewall corp
Blackbox/configure/firewall corp> object
Blackbox/configure/firewall corp/object> nat-pool addresspoolDyna
dynamic 60.1.1.1 60.1.1.2
Blackbox/configure/firewall corp/object> exit
Blackbox/configure/firewall corp> policy 8 out address 10.1.1.1
10.1.1.4 any any
Blackbox/configure/firewall corp/policy 8 out> apply-object
nat-pool addresspoolDyna
Blackbox/configure/firewall corp/policy 8 out> exit 2
Blackbox/configure>