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Advanced Settings
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CENTRIA WNDR4700/WNDR4720
2.
Select
Advanced > Advanced Setup > Wireless Repeating Function
to display the
Wireless Repeating Function screen.
Scroll to view
more settings
3.
Select the
Enable Wireless Repeating Function
check box and select the
Wireless Base
Station
radio button.
4.
Enter the MAC address for one or more repeater units.
5.
Click
Apply
to save your changes.
Set Up a Repeater Unit
Use a wired Ethernet connection to set up the repeater unit to avoid conflicts with the wireless
connection to the base station.
Note:
If you are using the WNDR4700/WNDR4720 base station with a
non-NETGEAR router as the repeater, you might need to change
additional configuration settings. In particular, you should disable the
DHCP server function on the wireless repeater
AP.
To configure the router as a repeater unit:
1.
Log in to the router that will be the repeater.
2.
Select
Basic > Wireless Settings
and
verify that the wireless settings match the base unit
exactly. The wireless security option must be set to None or WEP.
3.
Select
Advanced > Wireless Repeating Function
, and select the
Enable Wireless
Repeating Function
check box and the
Wireless Repeater
radio button.
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4.
Fill in the Repeater IP Address field. This IP address must be in the same subnet as the
base station, but different from the LAN IP address of the base station.
5.
Click
Apply
to save your changes.
6.
Verify connectivity across the LANs.
A computer on any wireless or wired LAN segment of the router can connect to the
Internet or share files and printers with any other wireless or wired computer or server
connected to the other access point.
Port Forwarding and Triggering
By default, the router blocks inbound traffic from the Internet to your computers except replies
to your outbound traffic. You might need to create exceptions to this rule for these purposes:
To allow remote computers on the Internet to access a server on your local network.
To allow certain applications and games to work correctly when your router does not
recognize their replies.
Your router provides two features for creating these exceptions: port forwarding and port
triggering. The next sections provide background information to help you understand how
port forwarding and port triggering work, and the differences between the two.
Remote Computer Access Basics
When a computer on your network needs to access a computer on the Internet, your
computer sends your router a message containing the source and destination address and
process information. Before forwarding your message to the remote computer, your router
has to modify the source information and create and track the communication session so that
replies can be routed back to your computer.
Here is an example of normal outbound traffic and the resulting inbound responses:
1.
You open a browser and your operating system assigns port number 5678 to this
browser session.
2.
You type http://www.example.com into the URL field, and your computer creates a web page
request message with the following address and port information. The request message is
sent to your router.
Source address
. Your computer’s IP address.
Source port number
. 5678, which is the browser session.
Destination address
. The IP address of www.example.com, which your computer finds
by asking a DNS server.
Destination port number
. 80, which is the standard port number for a web server
process.
3.
Your router creates an entry in its internal session table describing this communication
session between your computer and the web server at www.example.com. Before sending
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the web page request message to www.example.com, your router stores the original
information and then modifies the source information in the request message, performing
Network Address Translation (NAT):
The source address is replaced with your router’s public IP address. This is necessary
because your computer uses a private IP address that is not globally unique and cannot
be used on the Internet.
The source port number is changed to a number chosen by the router, such as 33333.
This is necessary because two computers could independently be using the same
session number.
Your router then sends this request message through the Internet to the web server at
www.example.com.
4.
The web server at www.example.com composes a return message with the requested web
page data. The return message contains the following address and port information. The
web server then sends this reply message to your router.
Source address
. The IP address of www.example.com.
Source port number
. 80, which is the standard port number for a web server process.
Destination address
. The public IP address of your router.
Destination port number
. 33333.
5.
Upon receiving the incoming message, your router checks its session table to determine
whether there is an active session for port number 33333. Finding an active session, the
router then modifies the message to restore the original address information replaced by
NAT. Your router sends this reply message to your computer, which displays the web page
from www.example.com. The message now contains the following address and port
information.
Source address
. The IP address of www.example.com.
Source port number
. 80, which is the standard port number for a web server process.
Destination address
. Your computer’s IP address.
Destination port number
. 5678, which is the browser session that made the initial
request.
6.
When you finish your browser session, your router eventually detects a period of inactivity in
the communications. Your router then removes the session information from its session
table, and incoming traffic is no longer accepted on port number 33333.
Port Triggering to Open Incoming Ports
In the preceding example, requests are sent to a remote computer by your router from a
particular service port number. Replies from the remote computer to your router are directed
to that port number. If the remote server sends a reply to a different port number, your router
does not recognize it and discards it. However, some application servers (such as FTP and
IRC servers) send replies to multiple port numbers. Using the port triggering function of your
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router, you can tell the router to open additional incoming ports when a particular outgoing
port originates a session.
An example is Internet Relay Chat (IRC). Your computer connects to an IRC server at
destination port 6667. The IRC server not only responds to your originating source port, but
also sends an “identify” message to your computer on port 113. Using port triggering, you can
tell the router, “When you initiate a session with destination port 6667, you have to also allow
incoming traffic on port 113 to reach the originating computer.” Using steps similar to the
preceding example, the following sequence shows the effects of the port triggering rule you
have defined:
1.
You open an IRC client program to start a chat session on your computer.
2.
Your IRC client composes a request message to an IRC server using a destination port
number of 6667, the standard port number for an IRC server process. Your computer
then sends this request message to your router.
3.
Your router creates an entry in its internal session table describing this communication
session between your computer and the IRC server. Your router stores the original
information, performs Network Address Translation (NAT) on the source address and
port, and sends this request message through the Internet to the IRC server.
4.
Noting your port triggering rule and having observed the destination port number of
6667, your router creates an additional session entry to send any incoming port 113
traffic to your computer.
5.
The IRC server sends a return message to your router using the NAT-assigned source
port (as in the previous example, say port 33333) as the destination port. The IRC
server also sends an “identify” message to your router with destination port 113.
6.
Upon receiving the incoming message to destination port 33333, your router checks its
session table to determine whether there is an active session for port number 33333.
Finding an active session, the router restores the original address information replaced
by NAT and sends this reply message to your computer.
7.
Upon receiving the incoming message to destination port 113, your router checks its
session table and learns that there is an active session for port 113, associated with
your computer. The router replaces the message’s destination IP address with your
computer’s IP address and forwards the message to your computer.
8.
When you finish your chat session, your router eventually senses a period of inactivity in
the communications. The router then removes the session information from its session
table, and incoming traffic is no longer accepted on port numbers 33333 or 113.
To configure port triggering, you need to know which inbound ports the application needs.
Also, you need to know the number of the outbound port that will trigger the opening of the
inbound ports. Usually, you can determine this information by contacting the publisher of the
application or the relevant user groups or news groups.
Note:
Only one computer at a time can use the triggered application.
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Port Forwarding to Permit External Host Communications
In both of the preceding examples, your computer initiates an application session with a
server computer on the Internet. However, you might need to allow a client computer on the
Internet to initiate a connection to a server computer on your network. Normally, your router
ignores any inbound traffic that is not a response to your own outbound traffic. You can
configure exceptions to this default rule by using the port forwarding feature.
A typical application of port forwarding can be shown by reversing the client-server
relationship from the previous web server example. In this case, a remote computer’s
browser needs to access a web server running on a computer in your local network. Using
port forwarding, you can tell the router, “When you receive incoming traffic on port 80 (the
standard port number for a web server process), forward it to the local computer at
192.168.1.123.” The following sequence shows the effects of the port forwarding rule you
have defined:
1.
The user of a remote computer opens a browser and requests a web page from
www.example.com, which resolves to the public IP address of your router. The remote
computer composes a web page request message with the following destination
information:
Destination address
. The IP address of www.example.com, which is the address of your
router.
Destination port number
. 80, which is the standard port number for a web server
process.
The remote computer then sends this request message through the Internet to your
router.
2.
Your router receives the request message and looks in its rules table for any rules
covering the disposition of incoming port 80 traffic. Your port forwarding rule specifies
that incoming port 80 traffic should be forwarded to local IP address 192.168.1.123.
Therefore, your router modifies the destination information in the request message:
The destination address is replaced with 192.168.1.123.
Your router then sends this request message to your local network.
3.
Your web server at 192.168.1.123 receives the request and composes a return message
with the requested web page data. Your web server then sends this reply message to
your router.
4.
Your router performs NAT on the source IP address, and sends this request message
through the Internet to the remote computer, which displays the web page from
www.example.com.
To configure port forwarding, you need to know which inbound ports the application needs.
Usually, you can determine this information by contacting the publisher of the application or
the relevant user groups or news groups.

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