Network Address Translation

Network Address Translation - NAT
Network address translation (NAT) is a process that converts network addresses between two different networks. NAT is typically used to convert public network addresses (such as IP addresses) into private local network addresses that are not recognized on the Internet. NAT provides added security as computers connected through public networks cannot access local computers with private network addresses.

Network Address Translation (NAT) Operation

This figure shows the basic operation of a network address translation (NAT) system. In this diagram, the NAT receives a message with a desired pubic IP address (209.67.22.59) originating from a local computer with a private IP address of 10.01.01.01. The NAT translates this originating address to a public IP originating address. The NAT then initiates a session with the Internet server (web site) using the network's public IP address 118.54.23.11 as the originating address. The Internet server receives the request for information and responds with data messages address to the NAT's public IP address. When the NAT receives these data messages for that particular communications session, they are translated to the local (private) IP address 10.01.01.01 and forwarded to the originating computer. If messages are received to the NAT's public IP address that are not part of a communications session that it knows about, the NAT will not route the messages to computers connected to the LAN.

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Session Initiation Protocol - SIP Book
This book explains why people and companies are using SIP equipment and software to efficiently upgrade existing telephone systems, develop their own advanced communications services, and to more easily integrate telephone network with company information systems. This book also provides descriptions of the function parts of SIP systems and operations.

$19.99 Printed, $16.99 eBook