In networking terms, Network Address Translation, NAT, is
the process of modifying IP Address information in the headers of IP packet
during the movement across a traffic routing device. The most basic type of NAT
provides a one-to-one translation of IP addresses. RFC 2663 type NAT is also
known as the most basic form of NAT. In a basic NAT, only the IP addresses, IP
header checksum and any other higher level checksums that involves IP address
need to be edited, leaving the remaining of the packet untouched. Basic NATs
are usually used when there is a need to interconnect two IP networks with
conflicting addressing. Although it is common to hide an entire IP address
space, usually made up of private IP addresses behind either a single IP
address or in another address space.
As mentioned, NAT enables communication through the router
only when the conversion originates in the masked network, since this creates
the translation tables. However, most up-to-date NAT devices allow the network
administrator to configure translation table entries for permanent use. This is
known as static NAT/port forwarding and it allows traffic from the outside
network to reach their destination host in the masked network.
However, NAT has some grave flaws on the quality of Internet
connectivity and requires careful attention to the details of its
implementation. In particular, all types of NAT break the initial image model
of IP end-to-end connectivity across the Internet and NAPT makes it difficult
for systems behind a NAT to accept incoming communications. Thus NAT traversal
methods have been implemented to ease the problems that occurred.
PAT, which is also known as Port Address Translation, on the other hand
provides most services that are similar to what NAT provides, except that PAT
allows many internal hosts to share a single external IP address and for users
who does not need inbound connection support do not consume public IP addresses
Jeremy's post allow me to understand network address translation better. He manage to explain it well in simple term without confusing readers. I learn a lot through his post. He gave me a better knowledge and understanding of the network address translation.
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