Network Address
Translation (NAT/NAPT)
Network Address Translation (NAT-- see RFC
1631) and Network Address Port Translation (NAPT)
enable network administrators to partition an IP network
between 'public' and 'private' IP addresses. Public IP
addresses are provided for external communication, and
private IP addresses such as those in the 10.x.x.x range
are used for internal communication. Computers with private
addresses are able to communicate via the public network
via Network Address Translation.
Outgoing Network Address Translation
For enabling private computers to connect to remote servers
on the public network, KarlNet products can be upgraded
with Network Address Port Translator support. The NAPT
feature allows multiple computers to share a single IP
address to connect to any IP network, including the Internet.
Instead of having to provide a public IP address for every
computer that will connect to the Internet, a single IP
address is given to the KarlBridge or KarlRouter, and
the connected computers use private, non-routable IP addresses,
such as 10.x.x.x.
Outgoing Network Address Port Translation is especially
useful when combined with KarlNet's DHCP
Server feature. All computers connecting to the KarlBridge
can automatically obtain their private IP address from
the KarlBridge. When the KarlBridge also obtains its IP
address as a DHCP Client, you have a network device that
is truly plug-and-play.
Incoming Network Address Translation
Normal Outgoing Network Address Port Translation is useful
only when none of the systems behind the NAT will act
as public servers on the Internet. When systems behind
a NAT will act as web or FTP servers for access over the
Internet, some form of Incoming NAT is necessary. The
incoming NAT allows you have requests to a server on the
NAT's public IP address(es) be redirected to a system
that is using a private IP address behind the NAT. In
this way, the NAT enables you to provide Internet access
to multiple computers with a single public IP address,
and also to have publicly available servers.
The Incoming and Outgoing NAT features are especially
useful for Internet connection sharing for cable modems
or dialup lines. For more information on using KarlNet
products with dialup lines, see our PPP
feature.
For examples of how Network Address Translation can be
applied in your network, visit the Solutions
section of our Online Library.
