ZyXEL NBG4615 v2 User Guide - Page 168

What You Need To Know

Page 168 highlights

Chapter 18 NAT • Use the Port Forwarding screen to set a default server and change your NBG4615 v2's port forwarding settings to forward incoming service requests to the server(s) on your local network (Section 18.3 on page 170). • Use the Port Trigger screen to change your NBG4615 v2's trigger port settings (Section 18.5.3 on page 175). 18.1.2 What You Need To Know The following terms and concepts may help as you read through this chapter. Inside/Outside This denotes where a host is located relative to the NBG4615 v2, for example, the computers of your subscribers are the inside hosts, while the web servers on the Internet are the outside hosts. Global/Local This denotes the IP address of a host in a packet as the packet traverses a router, for example, the local address refers to the IP address of a host when the packet is in the local network, while the global address refers to the IP address of the host when the same packet is traveling in the WAN side. Note: Inside/outside refers to the location of a host, while global/local refers to the IP address of a host used in a packet. An inside local address (ILA) is the IP address of an inside host in a packet when the packet is still in the local network, while an inside global address (IGA) is the IP address of the same inside host when the packet is on the WAN side. The following table summarizes this information. Table 68 NAT Definitions ITEM Inside Outside Local Global DESCRIPTION This refers to the host on the LAN. This refers to the host on the WAN. This refers to the packet address (source or destination) as the packet travels on the LAN. This refers to the packet address (source or destination) as the packet travels on the WAN. Note: NAT never changes the IP address (either local or global) of an outside host. What NAT Does In the simplest form, NAT changes the source IP address in a packet received from a subscriber (the inside local address) to another (the inside global address) before forwarding the packet to the WAN side. When the response comes back, NAT translates the destination address (the inside global address) back to the inside local address before forwarding it to the original inside host. Note that the IP address (either local or global) of an outside host is never changed. The global IP addresses for the inside hosts can be either static or dynamically assigned by the ISP. In addition, you can designate servers, for example, a web server and a telnet server, on your local 168 NBG4615 v2 User's Guide

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Chapter 18 NAT
NBG4615 v2 User’s Guide
168
Use the
Port Forwarding
screen to set a default server and change your NBG4615 v2’s port
forwarding settings to forward incoming service requests to the server(s) on your local network
(
Section 18.3 on page 170
).
Use the
Port Trigger
screen to change your NBG4615 v2’s trigger port settings (
Section 18.5.3
on page 175
).
18.1.2
What You Need To Know
The following terms and concepts may help as you read through this chapter.
Inside/Outside
This denotes where a host is located relative to the NBG4615 v2, for example, the computers of
your subscribers are the inside hosts, while the web servers on the Internet are the outside hosts.
Global/Local
This denotes the IP address of a host in a packet as the packet traverses a router, for example, the
local address refers to the IP address of a host when the packet is in the local network, while the
global address refers to the IP address of the host when the same packet is traveling in the WAN
side.
Note: Inside/outside refers to the location of a host, while global/local refers to the IP
address of a host used in a packet.
An inside local address (ILA) is the IP address of an inside host in a packet when the packet is still
in the local network, while an inside global address (IGA) is the IP address of the same inside host
when the packet is on the WAN side. The following table summarizes this information.
Note: NAT never changes the IP address (either local or global) of an outside host.
What NAT Does
In the simplest form, NAT changes the source IP address in a packet received from a subscriber
(the inside local address) to another (the inside global address) before forwarding the packet to the
WAN side. When the response comes back, NAT translates the destination address (the inside
global address) back to the inside local address before forwarding it to the original inside host. Note
that the IP address (either local or global) of an outside host is never changed.
The global IP addresses for the inside hosts can be either static or dynamically assigned by the ISP.
In addition, you can designate servers, for example, a web server and a telnet server, on your local
Table 68
NAT Definitions
ITEM
DESCRIPTION
Inside
This refers to the host on the LAN.
Outside
This refers to the host on the WAN.
Local
This refers to the packet address (source or destination) as the packet travels on the LAN.
Global
This refers to the packet address (source or destination) as the packet travels on the WAN.