Netgear C3000 N300 Wifi Cable Modem Router User Manual

							Specify Internet Port Settings 
91  N300 WiFi Cable Modem Router Model C3000
How the Modem Router Implements the Port Forwarding Rule
The following sequence shows the effects of a port forwarding rule:
1. When you type the URL www.example.com in your browser, the browser sends 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 modem router.
•Destination port number. 80, which is the standard port number for a web server 
process.
2. Your modem router receives the message and finds your port forwarding rule for incoming 
port 80 traffic. 
3. The modem router changes the destination in the message to IP address 192.168.0.123 
and sends the message to that computer.
4. Your web server at IP address 192.168.0.123 receives the request and sends a reply 
message to your modem router.
5. Your modem router performs Network Address Translation (NAT) on the source IP address, 
and sends the reply through the Internet to the computer or wireless device that sent the 
web page request. 
Set Up Port Triggering
Port triggering is a dynamic extension of port forwarding that is useful in these cases:
•An application uses port forwarding to more than one local computer (but not 
simultaneously).
•An application opens incoming ports that are different from the outgoing port.
With port triggering, the modem router monitors traffic to the Internet from an outbound 
“trigger” port that you specify. For outbound traffic from that port, the modem router saves the 
IP address of the computer that sent the traffic. The modem router temporarily opens the 
incoming port or ports that you specify in your rule, and forwards that incoming traffic to that 
destination.
Port forwarding creates a static mapping of a port number or range of ports to a single local 
computer. Port triggering can dynamically open ports to any computer when needed and 
close the ports when they are no longer needed.
Note:If you use applications such as multiplayer gaming, peer-to-peer 
connections, real-time communications such as instant messaging, or 
remote assistance (a feature in Windows XP), enable Universal Plug 
and Play (UPnP). See 
Improve Network Connections with Universal 
Plug and Play on page 63. 
						

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N300 WiFi Cable Modem Router Model C3000 
Add a Port Triggering Service
To add a port triggering service:
1. 
Launch a web browser from a computer or wireless device that is connecte\
d to the 
network.
2.  T
ype  http://routerlogin.net  or http://192.168.0.1.
A login screen displays.
3.  Enter the modem router user name and password.
The user name is  admin. 
 The default password is password . The user name and 
password are case-sensitive.
The BASIC Home screen displays.
4.  Select  ADV
 ANCED > Advanced Setup > Port Forwarding/Port Triggering. 
5.  Select the  Port T
 riggering radio button.
6. Click the  Add Service button.
7. In the Service Name field, type a descriptive service name. 
8.  In the Service User list, select  Any
 , or select Single address and enter the IP address of 
one computer: 
						

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 N300 WiFi Cable Modem Router Model C3000
•
Any  (the default) allows any computer on the Internet to use this service\
. 
• Single address restricts the service to a particular computer
 . 
9.  Select the service type, either  TCP or UDP or  TCP/UDP (both). 
If you are not sure, select TCP/UDP .
10.  In the T
riggering Port  field, enter the number of the outbound traffic port that will open the 
inbound ports. 
11.  Enter the inbound connection port information in the  Connection T
 ype, Starting Port, and 
Ending Port  fields.
12.  Click the  Apply button.
The service is now in the Portmap table. You must enable port triggering before the  modem router  uses port triggering. See Specify When to Use Port Triggering on page  93.
Specify When to Use Port Triggering
To specify when to use port triggering: 
1. Launch a web browser from a computer or wireless device that is connecte\
d to the 
network.
2.  T
ype  http://routerlogin.net  or http://192.168.0.1.
A login screen displays.
3.  Enter the modem router user name and password.
The user name is  admin. 
 The default password is password. The user name and 
password are case-sensitive.
The BASIC Home screen displays.
4.  Select  ADV
 ANCED > Advanced Setup > Port Forwarding/Port Triggering.
5.  Select the Port T
 riggering radio button.
6. Select a radio button to specify when you want to use port triggering: 
						

							Specify Internet Port Settings 
94 N300 WiFi Cable Modem Router Model C3000 
•Never. The modem router does not use port triggering even if you have specified port 
triggering settings.
•Per Schedule. Port triggering is used based on the settings in the Schedule screen.
•Always. Always use port triggering.
7. In the Port Triggering Timeout field, enter a value up to 9999 minutes. 
This value controls how long the inbound ports stay open when the modem router detects 
no activity. This value is required because the modem router cannot detect when the 
application terminates.
Application Example: Port Triggering for Internet Relay Chat 
Some application servers, such as FTP and IRC servers, send replies to multiple port 
numbers. Using port triggering, you can tell the modem router to open more incoming ports 
when a particular outgoing port starts 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 modem router, “When you initiate a session with destination port 6667, you must also 
allow incoming traffic on port 113 to reach the originating computer.” 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 modem router.
3. Your modem router creates an entry in its internal session table describing this 
communication session between your computer and the IRC server. Your modem 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. Based on the port triggering rule with the destination port number of 6667, the modem router 
creates another session entry to send any incoming port 113 traffic to your computer.
5. The IRC server sends a return message to your modem router using the NAT-assigned 
source port (for example, port 33333) as the destination port. The IRC server also sends an 
“identify” message to your modem router with destination port 113.
6. When your modem router receives the incoming message to destination port 33333, it 
checks its session table to see if a session is active for port number 33333. Finding an active 
session, the modem router restores the original address information replaced by NAT and 
sends this reply message to your computer.
7. When your modem router receives the incoming message to destination port 113, it checks 
its session table and finds an active session for port 113 associated with your computer. The 
modem 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 modem router eventually senses a period of 
inactivity in the communications. The modem router removes the session information from 
its session table, and incoming traffic is no longer accepted on port numbers 33333 or 113. 
						

							95
9
9.   Troubleshooting
This chapter gives information about troubleshooting your modem router. 
This chapter includes the following sections:
•Use LEDs to Troubleshoot 
•Cannot Log In to the Modem Router 
•Troubleshoot the ISP Connection 
•Troubleshoot a TCP/IP Network Using a Ping Utility 
Tip:NETGEAR provides helpful articles, documentation, and the latest 
software updates at 
support.netgear.com. 
						

							Troubleshooting 96
N300 WiFi Cable Modem Router Model C3000 
Use LEDs to Troubleshoot
The following table provides help when using the LEDs for troubleshootin\
g.
Table 3.  LED troubleshooting
LED BehaviorAction
All LEDS are off when the modem  router is plugged in. Make sure that the power cord is properly connected to your modem 
router and that the power supply adapter is properly connected to a 
functioning power outlet. 
Check that you are using the 12 VDC power adapter from NETGEAR 
for this product.
If the error persists, you have a hardware problem. Contact technical 
support.
All LEDs stay on. • Clear the configuration of the modem router to its factory defaults. 
This operation sets the IP address of the modem router to  192.168.0.1. See  Factory Default Settings on page  101. 
•  If the error persists, you have a hardware problem. Contact 
technical support.
LAN LED is off for a port with an 
Ethernet connection. • 
Make sure that the Ethernet cable connections are secure at the 
modem router and at the hub or computer

.
•  Make sure that power is turned on to the connected hub or 
computer

.
•  Be sure that you are using the correct cable.
Internet LED is off and the modem 
router is connected to the cable 
television cable. • 
Make sure that the coaxial cable connections are secure at the 
modem router and at the wall jack.
•  Make sure that your cable service provider has provisioned your 
cable Internet service. 

Your provider can verify that the signal 
quality is good enough for modem router service.
•  Remove any excessive splitters that you have on your cable line. 
Run a “home run” back to the point where the cable enters your 
home.
Cannot Log In to the Modem Router
If you cannot access the modem router from a computer on your local netw\
ork, check the 
following:
• If you are using a WiFi connection, check to make sure that your compute\
r or mobile 
device is connected to the correct WiFi network.
• If your computer is connected to the modem router wtih an Ethernet cable\
, check the 
connection.
• Make sure that your computer
 ’s IP address is on the same subnet as the modem router. 
If you are using the recommended addressing scheme, the address of your \
computer is 
in the range of 192.168.0.10 to 192.168.0.254.  
						

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97  N300 WiFi Cable Modem Router Model C3000
Note:If the IP address of your computer is shown as 169.254.x.x: 
Recent versions of Windows and Mac OS generate and assign an IP 
address when the computer cannot reach a DHCP server. These 
autogenerated addresses are in the range of 169.254.x.x. If your IP 
address is in this range, check the connection from the computer to 
the modem router and reboot your computer.
•If the IP address of your modem router has been changed and you do not know its 
current IP address, clear the configuration of the modem router to its factory defaults. 
This sets the IP address of the modem router to 192.168.0.1. For more information, see 
Factory Default Settings on page 101.
•Make sure that your browser has Java, JavaScript, or ActiveX enabled. If you are using 
Internet Explorer, click the Refresh button to make sure that the Java applet is loaded.
•Try quitting the browser and launching it again.
•Make sure that you are using the correct login information. The modem router user name 
admin is lowercase (Caps Lock is off). The default password is password. 
If the modem router does not save changes you have made, do the following:
•When entering configuration settings, be sure to click the Apply button before moving to 
another screen, or your changes are lost. 
•Click the Refresh or Reload button in the web browser. The changes have occurred, but 
the web browser might be caching the old configuration.
Troubleshoot the ISP Connection
When your modem router cannot access the Internet and your Internet LED is on, register 
the cable MAC address or device MAC address of your modem router with your cable service 
provider. 
Additionally, your computer might not have the modem router configured as its TCP/IP 
gateway. If your computer obtains its information from the modem router by DHCP, reboot the 
computer and verify the gateway address.
Troubleshoot a TCP/IP Network Using a Ping Utility
Most TCP/IP terminal devices and routers contain a ping utility that sends an echo request 
packet to the designated device. The device then responds with an echo reply. You can 
easily troubleshoot a TCP/IP network by using the ping utility in your computer or 
workstation. 
						

							Troubleshooting 
98 N300 WiFi Cable Modem Router Model C3000 
Use Ping to Test the LAN Path to Your Gateway
You can use ping to verify that the LAN path to your modem router is set up correctly.
To ping the modem router from a computer running Windows 95 or later:
1. From the Windows toolbar, click the Start button and select Run.
2. In the field that is provided, type ping and then the IP address of the modem router, as in 
this example:
ping 192.168.0.1
3. Click the OK button.
You see a message like the following:
Pinging  with 32 bytes of data
If the path is working, you see this message:
Reply from < IP address >: bytes=32 time=NN ms TTL=xxx
If the path is not working, you see this message:
Request timed out
If the path is not working correctly, you could have one of the following problems:
•Wrong physical connections.
-Make sure that the LAN LED is lit. If this LED is off. for more information, see Use 
LEDs to Troubleshoot on page 96.
-Check the corresponding link LEDs are on for your network interface card and the 
hub ports (if any) that are connected to your workstation and modem router.
•Wrong network configuration.
-Verify that the Ethernet card driver software and TCP/IP software are both 
installed and configured on your computer or workstation.
-Verify that the IP address for your modem router and your workstation are correct 
and that the addresses are on the same subnet.
Use Ping to Test the Path from a Windows Computer to a 
Remote Device
After verifying that the LAN path works correctly, test the path from the Windows computer to 
a remote device. 
To test the path from a Windows computer to a remote device:
1. From the Windows toolbar, click the Start button and select Run.
where  is the IP address of a remote device such as the DNS server of your 
ISP. 
						

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99  N300 WiFi Cable Modem Router Model C3000
If the path is working, you see this message:
Reply from < IP address >: bytes=32 time=NN ms TTL=xxx
2. If you do not receive this reply, do the following:
•Check that the Internet LED is lit.
•If your ISP assigned a host name to your computer, enter that host name as the 
account name in the Internet Setup screen.
•Check that your computer has the IP address of your modem router listed as the 
default gateway. If DHCP assigns the IP configuration of your computer, this 
information is not visible in the Network Control Panel of your computer. 
•Check that the network address of your computer (the portion of the IP address 
specified by the netmask) is different from the network address of the remote device. 
						

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A
A.   Supplemental Information
This appendix includes the following sections.
•Factory Default Settings 
•Technical Specifications