Editing Network address translation (section)

{{Short description|Technique for traversing IP address spaces without routing}}
{{Use American English|date=February 2022}} 
[[File:NAT Concept-en.svg|thumb|Network address translation between a private network and the Internet]]
'''Network address translation''' ('''NAT''') is a method of mapping an IP [[address space]] into another by modifying [[network address]] information in the [[IP header]] of packets while they are in transit across a traffic [[Router (computing)|routing device]].<ref>{{cite book
|edition= 2
|title= Network Protocols Handbook
|url= https://books.google.com/books?id=D_GrQa2ZcLwC
|publisher= Javvin Technologies Inc.
|date= 2005
|page= 27
|isbn= 9780974094526
|access-date= 2014-09-16
}}</ref>  The technique was initially used to bypass the need to assign a new address to every host when a network was moved, or when the upstream [[Internet service provider]] was replaced but could not route the network's address space. It has become a popular and essential tool in conserving global address space in the face of [[IPv4 address exhaustion]]. One Internet-routable [[IP address]] of a NAT gateway can be used for an entire [[private network]].<ref name="rfc4787" />

As network address translation modifies the IP address information in packets, NAT implementations may vary in their specific behavior in various addressing cases and their effect on network traffic. Vendors of equipment containing NAT implementations do not commonly document the specifics of NAT behavior.<ref name="rfc4787">{{cite IETF
|author1=François Audet
|author2=Cullen Jennings
|rfc=4787
|title=Network Address Translation (NAT) Behavioral Requirements for Unicast UDP
|publisher=[[IETF]]
|date=January 2007
}}</ref>