CHAPTER 3. Firewall NAT240 © SAMSUNG Electronics Co., Ltd.NAT configuration ExamplesDynamic NAT (many to many)In dynamic(many-to-many) NAT type, multiple source IP addresses in thecorporate network will be mapped to multiple NAT IP addresses(notnecessarily of equal number). For a set of local IP address from 10.1.1.1 to10.1.1.4 there will be a set of NAT IP address from 60.1.1.1 to 60.1.1.2. Incase of many-to-many NAT, only IP address translation takes place, i.e., if apacket travels from 10.1.1.1 to yahoo.com, Firewall only substitutes thesource address in the IP header with one of the NAT IP address and the sourceport will be the same as the original. If traffic emanates from the same clientto any other server, the same NAT IP address is assigned. The advantage isthat the NAT IP addresses are utilized in a better and optimum mannerdynamically.If a NAT IP address cannot be allocated dynamically at the connectioncreation time, the packet would be dropped.Figure 3.4 Dynamic NATThe dynamic NAT configuration shown in Figure 25.4 includes:y Private network addresses:10.1.1.1-10.1.1.4y Public(NAT) IP address range: 60.1.1.1-60.1.1.210.1.1.110.1.1.210.1.1.360.1.1.1.60.1.1.2InternetOPAL
