Netgear Router WGT624 V3 User Manual

							Reference Manual for the 108 Mbps Wireless Firewall Router WGT624 v3
Network, Routing, Firewall, and Basics B-11
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Stateful Packet Inspection
Unlike simple Internet sharing routers, a firewall uses a process called stateful packet inspection to 
ensure secure firewall filtering to protect your network from attacks and intrusions. Since 
user-level applications such as FTP and web browsers can create complex patterns of network 
traffic, it is necessary for the firewall to analyze groups of network connection states. Using 
Stateful Packet Inspection, an incoming packet is intercepted at the network layer and then 
analyzed for state-related information associated with all network connections. A central cache 
within the firewall keeps track of the state information associated with all network connections. 
All traffic passing through the firewall is analyzed against the state of these connections in order to 
determine whether or not it will be allowed to pass through or rejected.
Denial of Service Attack
A hacker may be able to prevent your network from operating or communicating by launching a 
Denial of Service (DoS) attack. The method used for such an attack can be as simple as merely 
flooding your site with more requests than it can handle. A more sophisticated attack may attempt 
to exploit some weakness in the operating system used by your router or gateway. Some operating 
systems can be disrupted by simply sending a packet with incorrect length information.
Ethernet Cabling
Most Ethernet networks now use unshielded twisted pair (UTP) cabling. UTP cable has eight 
wires arranged in four twisted pairs, and terminated with an RJ45 connector. Normal straight- 
through UTP Ethernet cable follows the EIA568B standard as described in Ta b l e  B - 1.
Table B-1. UTP Ethernet cable wiring, straight-through
Pin Wire color Signal
1 Orange/White Transmit (Tx) +
2 Orange Transmit (Tx) -
3 Green/White Receive (Rx) +
4Blue
5 Blue/White
6 Green Receive (Rx) -
7 Brown/White
8Brown 
						

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Category 5 Cable Quality
Category 5 distributed cable that meets ANSI/EIA/TIA-568-A building wiring standards can be a 
maximum of 328 feet (ft.) or 100 meters (m) in length, divided as follows:
20 ft. (6 m) between the hub and the patch panel (if used)
295 ft. (90 m) from the wiring closet to the wall outlet
10 ft. (3 m) from the wall outlet to the desktop device
The patch panel and other connecting hardware must meet the requirements for 100 Mbps 
operation (Category 5). Only 0.5 inch (1.5 cm) of untwist in the wire pair is allowed at any 
termination point.
A twisted pair Ethernet network operating at 10 Mbits/second (10BASE-T) will often tolerate low 
quality cables, but at 100 Mbits/second (10BASE-Tx) the cable must be rated as Category 5, or 
Cat 5, by the Electronic Industry Association (EIA). This rating will be printed on the cable jacket. 
A Category 5 cable will meet specified requirements regarding loss and crosstalk. In addition, 
there are restrictions on maximum cable length for both 10 and 100 Mbits/second networks.
Inside Twisted Pair Cables
For two devices to communicate, the transmitter of each device must be connected to the receiver 
of the other device. The crossover function is usually implemented internally as part of the 
circuitry in the device. Computers and workstation adapter cards are usually media-dependent 
interface ports, called MDI or uplink ports. Most repeaters and switch ports are configured as 
media-dependent interfaces with built-in crossover ports, called MDI-X or normal ports.  Auto 
Uplink technology automatically senses which connection, MDI or MDI-X, is needed and makes 
the right connection.
Figure B-1 illustrates straight-through twisted pair cable. 
						

							Reference Manual for the 108 Mbps Wireless Firewall Router WGT624 v3
Network, Routing, Firewall, and Basics B-13
202-10090-01, April 2005 Figure B-1:  Straight-Through Twisted-Pair Cable
Figure B-2 illustrates crossover twisted pair cable.
Figure B-2:  Crossover Twisted-Pair Cable
Figure B-3:  Category 5 UTP Cable with Male RJ-45 Plug at Each End 
						

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Note: Flat “silver satin” telephone cable may have the same RJ-45 plug. However, using telephone 
cable results in excessive collisions, causing the attached port to be partitioned or disconnected 
from the network.
Uplink Switches, Crossover Cables, and MDI/MDIX Switching
In the wiring table above, the concept of transmit and receive are from the perspective of the PC, 
which is wired as Media Dependant Interface (MDI). In this wiring, the PC transmits on pins 1 and 
2. At the hub, the perspective is reversed, and the hub receives on pins 1 and 2. This wiring is 
referred to as Media Dependant Interface - Crossover (MDI-X). 
When connecting a PC to a PC, or a hub port to another hub port, the transmit pair must be 
exchanged with the receive pair. This exchange is done by one of two mechanisms. Most hubs 
provide an Uplink switch which will exchange the pairs on one port, allowing that port to be 
connected to another hub using a normal Ethernet cable. The second method is to use a crossover 
cable, which is a special cable in which the transmit and receive pairs are exchanged at one of the 
two cable connectors. Crossover cables are often unmarked as such, and must be identified by 
comparing the two connectors. Since the cable connectors are clear plastic, it is easy to place them 
side by side and view the order of the wire colors on each. On a straight-through cable, the color 
order will be the same on both connectors. On a crossover cable, the orange and blue pairs will be 
exchanged from one connector to the other.
The WGT624 v3 wireless router incorporates Auto Uplink
TM technology (also called MDI/MDIX). 
Each LOCAL Ethernet port will automatically sense whether the Ethernet cable plugged into the 
port should have a normal connection (e.g. connecting to a PC) or an uplink connection (e.g. 
connecting to a router, switch, or hub). That port will then configure itself to the correct 
configuration. This feature also eliminates the need to worry about crossover cables, as Auto 
Uplink
TM will accommodate either type of cable to make the right connection. 
						

							Preparing Your Network C-1
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Appendix C
Preparing Your Network
This appendix describes how to prepare your network to connect to the Internet through the 
WGT624 v3 108 Mbps Wireless Firewall Router and how to verify the readiness of broadband 
Internet service from an Internet service provider (ISP).
Preparing Your Computers for TCP/IP Networking
Computers access the Internet using a protocol called TCP/IP (Transmission Control Protocol/
Internet Protocol). Each computer on your network must have TCP/IP installed and selected as its 
networking protocol. If a Network Interface Card (NIC) is already installed in your PC, then TCP/
IP is probably already installed as well.
Most operating systems include the software components you need for networking with TCP/IP:
•Windows
® 95 or later includes the software components for establishing a TCP/IP network. 
• Windows 3.1 does not include a TCP/IP component. You need to purchase a third-party TCP/
IP application package such as NetManage Chameleon.
• Macintosh Operating System 7 or later includes the software components for establishing a 
TCP/IP network.
• All versions of UNIX or Linux include TCP/IP components. Follow the instructions provided 
with your operating system or networking software to install TCP/IP on your computer.
Note: If an ISP technician configured your computer during the installation of a 
broadband modem, or if you configured it using instructions provided by your ISP, you 
may need to copy the current configuration information for use in the configuration of 
your firewall. Write down this information before reconfiguring your computers. Refer 
to “Obtaining ISP Configuration Information for Windows Computers” on page C-19 or 
“Obtaining ISP Configuration Information for Macintosh Computers” on page C-20 for 
further information. 
						

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C-2 Preparing Your Network
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In your IP network, each PC and the firewall must be assigned a unique IP addresses. Each PC 
must also have certain other IP configuration information such as a subnet mask (netmask), a 
domain name server (DNS) address, and a default gateway address. In most cases, you should 
install TCP/IP so that the PC obtains its specific network configuration information automatically 
from a DHCP server during bootup. For a detailed explanation of the meaning and purpose of 
these configuration items, refer to “Appendix B, “Network, Routing, Firewall, and Basics.” 
The WGT624 v3 wireless router is shipped preconfigured as a DHCP server. The firewall assigns 
the following TCP/IP configuration information automatically when the PCs are rebooted:
• PC or workstation IP addresses—192.168.0.2 through 192.168.0.254
• Subnet mask—255.255.255.0
• Gateway address (the firewall)—192.168.0.1
These addresses are part of the IETF-designated private address range for use in private networks.
Configuring Windows 95, 98, and Me for TCP/IP Networking
As part of the PC preparation process, you need to manually install and configure TCP/IP on each 
networked PC. Before starting, locate your Windows CD; you may need to insert it during the 
TCP/IP installation process.
Install or Verify Windows Networking Components
To install or verify the necessary components for IP networking:
1.On the Windows taskbar, click the Start button, point to Settings, and then click Control Panel.
2.Double-click the Network icon.
The Network window opens, which displays a list of installed components: 
						

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You must have an Ethernet adapter, the TCP/IP protocol, and Client for Microsoft Networks.
If you need to install a new adapter, follow these steps:
a.Click the Add button.
b.Select Adapter, and then click Add.
c.Select the manufacturer and model of your Ethernet adapter, and then click OK.
If you need TCP/IP:
a.Click the Add button.
b.Select Protocol, and then click Add.
c.Select Microsoft.
d.Select TCP/IP, and then click OK.
Note: It is not necessary to remove any other network components shown in the 
Network window in order to install the adapter, TCP/IP, or Client for Microsoft 
Networks.  
						

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If you need Client for Microsoft Networks:
a.Click the Add button.
b.Select Client, and then click Add.
c.Select Microsoft.
d.Select Client for Microsoft Networks, and then click OK.
3.Restart your PC for the changes to take effect.
Enabling DHCP to Automatically Configure TCP/IP Settings
After the TCP/IP protocol components are installed, each PC must be assigned specific 
information about itself and resources that are available on its network. The simplest way to 
configure this information is to allow the PC to obtain the information from a DHCP server in the 
network. 
You will find there are many similarities in the procedures for different Windows systems 
when using DHCP to configure TCP/IP.
The following steps will walk you through the configuration process for each of these 
versions of Windows.
Locate your Network Neighborhood icon.
• If the Network Neighborhood icon is on the Windows desktop, position your mouse 
pointer over it and right-click your mouse button.
• If the icon is not on the desktop,
• Click Sta rt on the task bar located at the bottom left of the window.
• Choose Settings, and then Control Panel. 
• Locate the Network Neighborhood icon and click on it. This will open the Network 
panel as shown below. 
  
						

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Verify the following settings as shown: 
• Client for Microsoft Network exists
• Ethernet adapter is present
• TCP/IP is present
•Primary Network Logon is set to 
Windows logon
Click on the Properties button. The 
following TCP/IP Properties window will 
display.  
						

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Selecting Windows’ Internet Access Method
1.On the Windows taskbar, click the Start button, point to Settings, and then click Control Panel.
2.Double-click the Internet Options icon.
3.Select “I want to set up my Internet connection manually” or “I want to connect through a 
Local Area Network” and click Next.
4.Select “I want to connect through a Local Area Network” and click Next.
5.Uncheck all boxes in the LAN Internet Configuration screen and click Next.
6.Proceed to the end of the Wizard.
Verifying TCP/IP Properties
After your PC is configured and has rebooted, you can check the TCP/IP configuration using the 
utility winipcfg.exe:
1.On the Windows taskbar, click the Start button, and then click Run. • By default, the IP Address tab is open on 
this window.
• Verify the following:
Obtain an IP address automatically is 
selected. If not selected, click in the radio 
button to the left of it to select it.  This 
setting is required to enable the DHCP server 
to automatically assign an IP address. 
• Click OK to continue.
Restart the PC.
Repeat these steps for each PC with this 
version of Windows on your network.