Nat/Napt Server - Siemens 4100 Series User Manual

Router User's Guide

NAT/NAPT Server

Hosts located on a Local Area Network (LAN) are often required to use private IP addresses as opposed
to public IP addresses. Private IP addresses, however, are not known on the public Wide Area Network
(WAN). In order to expose LAN-side hosts assigned private IP addresses to the public WAN, the Router
can be configured to use one of two methodologies: Network Address Translation (NAT) or Network
Address Port Translation (NAPT). NAT can expose a single LAN-side host to the WAN; NAPT can
expose multiple LAN-side hosts. NAT/NAPT functionality can be individually configured for each WAN
connection.
To configure NAT/NAPT functionality:
1. Select Setup>NAT/NAPT from the left navigation pane of the Web interface. This displays the
"NAT/NAPT Configuration" window showing the WAN Interface connections.
2. Select one of the following for the desired connection:
• NAT & NAPT Disabled
Disable both NAT and NAPT in order, for example, to set up static routes assigned by your ISP.
• NAT Only Enabled
Enable NAT and specify the destination IP address for incoming packets. Depending on your
configuration, NAT is sometimes enabled by default.
• NAPT Only Enabled
Use NAPT only to handle multiple addresses based on port forwarding rules.
• NAT&NAPT Enabled
Some service providers support a concurrent NAT/NAPT. Under this configuration, a single WAN
interface may support multiple NAT connections with each NAT connection again exposing a
single LAN-side host through a single WAN-side public IP address. Through either NAT or NAPT,
the Router ensures that the LAN-side host is known to the WAN side only through the public IP
address of the Router's WAN-side connection. The host's actual private IP address remains
unknown to any WAN-side hosts or servers.
3. Click Apply when you have finished configuring all desired connections.
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Monitoring Network Health