1. Information Networking Security and Assurance Lab National Chung Cheng University Private IP(RFC1918) The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private internets. ClassFromTo Class "A" 10.0.0.010.255.255.255 Class "B" 172.16.0.0172.31.255.255 Class "C" 192.168.0.0192.168.255.255

2. Information Networking Security and Assurance Lab National Chung Cheng University Advantages: Increased security. You conserve the world-wide pool of IP Addresses. You do not have to register or pay for these IP Addresses in any way. Little or no performance degradation.

3. Information Networking Security and Assurance Lab National Chung Cheng University Disadvantages If you merge with a company that has chosen the same Private IP Address, one or both of you will have to re-number. This can be difficult and expensive. It may require more work to plan and configure.

4. Information Networking Security and Assurance Lab National Chung Cheng University NAT(Network Address Translation )RFC1631 enables a local-area network (LAN) to use one set of IP addresses for internal traffic

5. Information Networking Security and Assurance Lab National Chung Cheng University NAT serves three main purposes: Provides a type of firewall by hiding internal IP addresses. Enables a company to use more internal IP addresses. Since they're used internally only. Allows a company to combine multiple ISDN connections into a single Internet connection.

6. Information Networking Security and Assurance Lab National Chung Cheng University Sub-net Mask Subnetting is a technique that allows the network administrator to divide a network into smaller networks by using the same network number assignment.

7. Information Networking Security and Assurance Lab National Chung Cheng University The advantages of subnetting Simplified administration- With the help of routers networks can be broken up into smaller subnets that can managed more independently and efficiently. Restructuring of the internal network without affecting external networks- A organization can continue to use it's allocated IP addresses without having to obtain additional IP blocks.

8. Information Networking Security and Assurance Lab National Chung Cheng University Net Mask A Class 255.0.0.0 B Class 255.255.0.0 C Class 255.255.255.0