Network Address Translation

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Network Address Translation

(NAT, or Network Address Translator, Virtual LAN) A technique in which a router or firewall rewrites the source and/or destination Internet addresses in a packet as it passes through, typically to allow multiple hosts to connect to the Internet via a single external IP address. NAT keeps track of outbound connections and distributes incoming packets to the correct machine.

NAT is an alternative to adopting IPv6 (IPng). It allows the same IP addresses (10.x.x.x is the conventional range) to be used on many private local networks while requiring only one of the increasingly scarce public addresses to be allocated to each private network.

NAT does not however allow an external service to initiate a TCP connection to an internal host, nor does it support stateless protocols based on UDP well unless the router software has extensions to support each specific protocol.
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(Network Address Translation) The technology that maintains the privacy of the addresses of the computers in a home or business network when accessing the Internet. It converts the private addresses that are assigned to the internal computers to one or more public addresses that are visible on the Internet (see private IP address). NAT is an IETF standard that is implemented in a router or firewall as well as in any user's machine that is configured to share its Internet connection (see ICS).

NAT assigns a number to the packet headers of the messages going out to the Internet and keeps track of them via an internal table that it creates. When responses come back from the Internet, NAT uses the table to perform the reverse conversion to the private IP address of the requesting client machine (see illustration below).

A First-Level Firewall
NAT enhances security by keeping internal addresses hidden from the outside world. It prevents several kinds of first-level attacks, but not all, and must be used in conjunction with the firewall built into the router or the personal firewall in each user's machine. Enterprises generally use very robust firewall architectures for security (see firewall). See dynamic NAT.

NAT Port Address Translation (PAT)
This common NAT method assigns a different TCP port number to each client session with a server on the Internet. When responses come back, the source port becomes the destination port and determines which user to route the packets to. It also validates that the incoming packets were requested. See TCP/IP port.
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References in periodicals archive ?
The tool's built-in Network Address Translation (NAT) allows a session to be established even if the user's computer is behind a firewall or NAT device.
The NAT service is located on a carrier-grade NAT device (CGN) in the provider's network, which also is a tunnel terminator for the Pv4-in-IPv6 tunnel.
The MessengerSDK enhancements also follow Eyeball's previous updates to its popular AnyFirewall NAT traversal software, which enable PCs, tablets, and other devices to provide reliable communications through any firewall or NAT device.
According to the company, the new patents include: 7,570,636 - "System and method for traversing a NAT device for peer-to-peer hybrid communications"; 7,623,476 - "System and method for conferencing in a peer-to-peer hybrid communications network"; 7,623,516 - "System and method for deterministic routing in a peer-to-peer hybrid communications network"; and "7,656,870 - System and method for peer-to-peer hybrid communications".
The addition of new IPSec/TCP support extends the 3002 capabilities in Extranet environments, enabling users to connect to their "home" corporate network through a foreign firewall or NAT device.
A NAT device changing the IP addresses in the middle of a secure tunnel will transform packets in a way that resembles a "man in the middle" attack, thus causing the IPSec connection to fail.
Eyeball's AnyFirewall[TM] solutions enable other iPhone and iPad app developers to overcome the barriers associated with running applications from behind a corporate firewall, NAT device, or WiFI hotspot, and focus on delivering a high quality user experience.
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This is used to get through the NAT devices. There are two types of bubbles present.
Without going into the nitty-gritty about security, you will no longer have to worry about NAT devices with IPv6 if you make the switch.