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Default DMZ Server

The default DMZ server feature is helpful when you are using some online games and

videoconferencing applications that are incompatible with Network Address Translation

(NAT). The router is programmed to recognize some of these applications and to work

correctly with them, but there are other applications that might not function well. In some

cases, one local computer can run the application correctly if that computer’s IP address is

entered as the default DMZ server.

WARNING!

DMZ servers pose a security risk. A computer designated as the

default DMZ server loses much of the protection of the firewall and

is exposed to exploits from the Internet. If compromised, the DMZ

server computer can be used to attack other computers on your

network.

Incoming traffic from the Internet is usually discarded by the router unless the traffic is a

response to one of your local computers or a service that you have configured in the Port

Forwarding/Port Triggering screen. Instead of discarding this traffic, you can have it

forwarded to one computer on your network. This computer is called the default DMZ server.



To set up a default DMZ server:

1.

On the WAN Setup screen, select the

Default DMZ Server

check box.

2.

Type the IP address.

3.

Click

Apply

.

Change the MTU Size

The Maximum Transmission Unit (MTU) is the largest data packet a network device

transmits. When one network device communicates across the Internet with another, the data

packets travel through many devices along the way. If any device in the data path has a lower

MTU setting than the other devices, the data packets have to be split or “fragmented” to

accommodate the device with the smallest MTU.

The best MTU setting for NETGEAR equipment is often just the default value, and changing

the value might fix one problem but cause another. Leave MTU unchanged unless one of

these situations occurs:

•

You have problems connecting to your ISP or other Internet service, and the technical

support of either the ISP or NETGEAR recommends changing the MTU setting. These

web-based applications might require an MTU change:

-

A secure website that will not open, or displays only part of a web page

-

Yahoo email

-

MSN portal

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-

America Online’s DSL service

•

You use VPN and have severe performance problems.

•

You used a program to optimize MTU for performance reasons, and now you have

connectivity or performance problems.

Note:

An incorrect MTU setting can cause Internet communication

problems such as the inability to access certain websites, frames

within websites, secure login pages, or FTP or POP servers.

If you suspect an MTU problem, a common solution is to change the MTU to 1400. If you are

willing to experiment, you can gradually reduce the MTU from the maximum value of 1500

until the problem goes away. The following table describes common MTU sizes and

applications.

Table 2.

Common MTU sizes

MTU

Application

1500

The largest Ethernet packet size and the default value. This is the typical setting for

non-PPPoE, non-VPN connections, and is the default value for NETGEAR routers,

adapters, and switches.

1492

Used in PPPoE environments.

1472

Maximum size to use for pinging. (Larger packets are fragmented.)

1468

Used in some DHCP environments.

1460

Usable by AOL if you do not have large email attachments, for example.

1436

Used in PPTP environments or with VPN.

1400

Maximum size for AOL DSL.

576

Typical value to connect to dial-up ISPs.



To change the MTU size:

1.

Select

Advanced > Setup > WAN Setup

.

2.

In the MTU Size field, enter a new size between 64 and 1500.

3.

Click

Apply

to save the settings.

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LAN Setup

The LAN Setup screen allows configuration of LAN IP services such as Dynamic Host

Configuration Protocol (DHCP) and Routing Information Protocol (RIP).

The router is shipped preconfigured to use private IP addresses on the LAN side and to act

as a DHCP server. The router’s default LAN IP configuration is:

•

LAN IP address.

192.168.1.1

•

Subnet mask.

255.255.255.0

These addresses are part of the designated private address range for use in private networks

and should be suitable for most applications. If your network has a requirement to use a

different IP addressing scheme, you can make those changes in the LAN Setup screen.



To change the LAN settings:

Note:

If you change the LAN IP address of the router while connected

through the browser, you will be disconnected. You will have to open

a new connection to the new IP address and log in again.

1.

Select

Advanced > Setup > LAN Setup

to display the following screen:

2.

Enter the settings that you want to customize. These settings are described in the following

section,

LAN Setup Screen Settings

.

3.

Click

Apply

to save your changes.

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LAN Setup Screen Settings

LAN TCP/IP Setup

•

IP Address

. The LAN IP address of the router.

•

IP Subnet Mask

. The LAN subnet mask of the router. Combined with the IP address, the

IP subnet mask allows a device to know which other addresses are local to it, and which

have to be reached through a gateway or router.

•

RIP Direction

. Router Information Protocol (RIP) allows a router to exchange routing

information with other routers. This setting controls how the router sends and recieves

RIP packets. Both is the default setting. With the Both or Out Only setting, the router

broadcasts its routing table periodically. With the Both or In Only setting, the router

incorporates the RIP information that it receives.

•

RIP Version

. This controls the format and the broadcasting method of the RIP packets

that the router sends. It recognizes both formats when receiving. By default, the RIP

function is disabled.

-

RIP-1

is universally supported. It is adequate for most networks, unless you have an

unusual network setup.

-

RIP-2

carries more information. Both RIP-2B and RIP-2M send the routing data in

RIP-2 format. RIP-2B uses subnet broadcasting. RIP-2M uses multicasting.

Use Router as a DHCP Server

This check box is usually selected so that the router functions as a Dynamic Host

Configuration Protocol (DHCP) server.

•

Starting IP Address

. Specify the start of the range for the pool of IP addresses in the

same subnet as the router.

•

Ending IP Address

. Specify the end of the range for the pool of IP addresses in the

same subnet as the router.

Address Reservation

When you specify a reserved IP address for a computer on the LAN, that computer receives

the same IP address each time it accesses the router’s DHCP server. Assign reserved IP

addresses to servers that require permanent IP settings.

Use the Router as a DHCP Server

By default, the router functions as a DHCP server, allowing it to assign IP, DNS server, and

default gateway addresses to all computers connected to the router’s LAN. The assigned

default gateway address is the LAN address of the router. The router assigns IP addresses to

the attached computers from a pool of addresses specified in this screen. Each pool address

is tested before it is assigned to avoid duplicate addresses on the LAN. For most

applications, the default DHCP and TCP/IP settings of the router are satisfactory.

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You can specify the pool of IP addresses to be assigned by setting the starting IP address

and ending IP address. These addresses should be part of the same IP address subnet as

the router’s LAN IP address. Using the default addressing scheme, you should define a range

between 192.168.1.2 and 192.168.1.254, although you might want to save part of the range

for devices with fixed addresses.

The router delivers the following parameters to any LAN device that requests DHCP:

•

An IP address from the range you have defined

•

Subnet mask

•

Gateway IP address (the router’s LAN IP address)

•

Primary DNS server (if you entered a primary DNS address in the Internet Setup screen;

otherwise, the router’s LAN IP address)

•

Secondary DNS server (if you entered a secondary DNS address in the Internet Setup

screen)

To use another device on your network as the DHCP server, or to manually configure the

network settings of all of your computers, clear the

Use Router as DHCP Server

check box

and click

Apply

. Otherwise, leave this check box selected. If this service is not enabled and

no other DHCP server is available on your network, you need to set your computers’ IP

addresses manually or they will not be able to access the router.

Address Reservation

When you specify a reserved IP address for a computer on the LAN, that computer always

receives the same IP address each time it accesses the router’s DHCP server. Reserved IP

addresses should be assigned to computers or servers that require permanent IP settings.



To reserve an IP address:

1.

In the Address Reservation section of the screen, click the

Add

button.

2.

In the IP Address field, type the IP address to assign to the computer or server. (Choose an

IP address from the router’s LAN subnet, such as 192.168.1.x.)

3.

Type the MAC address of the computer or server.

Tip:

If the computer is already on your network, you can copy its MAC

address from the Attached Devices screen and paste it here.

4.

Click

Apply

to enter the reserved address into the table.

The reserved address is not assigned until the next time the computer contacts the

router’s DHCP server. Reboot the computer or access its IP configuration and force a

DHCP release and renew.

To edit or delete a reserved address entry, select the radio button next to the reserved

address you want to edit or delete. Then click

Edit

or

Delete

.