N600 Wireless Dual Band Router WNDR3400 User Manual

Customizing Your Network Settings

5-4

v1.0, August 2010

Using 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. Click

the link to the online document

“TCP/IP Networking Basics” in Appendix B

for an explanation of

DHCP and information about how to assign IP addresses for your network.

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 wish 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 Basic Settings screen;

otherwise, the router’s LAN IP address)

•

Secondary DNS Server (if you entered a secondary DNS address in the Basic Settings 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. Otherwise,

leave it selected. If this service is not selected and no other DHCP server is available on your

network, you will 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.

Click

Add

.

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N600 Wireless Dual Band Router WNDR3400 User Manual

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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.

4.

Click

Apply

to enter the reserved address into the table.

To edit or delete a reserved address entry:

1.

Select the radio button next to the reserved address you want to edit or delete.

2.

Click

Edit

or

Delete

.

Using a Dynamic DNS Service

If your Internet Service Provider (ISP) gave you a permanently assigned IP address, you can

register a domain name and have that name linked with your IP address by public Domain Name

Servers (DNS). However, if your Internet account uses a dynamically assigned IP address, you do

not know in advance what your IP address will be, and the address can change frequently. In this

case, you can use a commercial Dynamic DNS service, which allows you to register your domain

to their IP address, and forwards traffic directed at your domain to your frequently changing IP

address.

Your router contains a client that can connect to the Dynamic DNS service provided by

DynDNS.org. You must first visit their website at

www.dyndns.org

and obtain an account and host

name, which you configure in the router. Then, whenever your ISP-assigned IP address changes,

Tip:

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

address from the Attached Devices screen and paste it here.

Note:

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.

Note:

If your ISP assigns a private WAN IP address (such as 192.168.x.x or 10.x.x.x), the

Dynamic DNS service will not work because private addresses are not routed on

the Internet.

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your router automatically contacts the Dynamic DNS service provider, logs in to your account, and

registers your new IP address. If your host name is hostname, for example, you can reach your

router at hostname.dyndns.org.

From the main menu, under Advanced, select

Dynamic DNS

to display the Dynamic DNS screen.

To configure Dynamic DNS:

1.

Register for an account with one of the Dynamic DNS service providers whose names appear

in the

Service Provider

list. For example, for DynDNS.org, select

www.dyndns.org

.

2.

Select the

Use a Dynamic DNS Service

check box.

3.

Select the name of your Dynamic DNS service provider.

4.

Type the host name (or domain name) that your Dynamic DNS service provider gave you.

5.

Type the user name for your Dynamic DNS account. This is the name that you use to log in to

your account, not your host name.

6.

Type the password (or key) for your Dynamic DNS account.

7.

If your Dynamic DNS provider allows the use of wildcards in resolving your URL, you can

select the

Use Wildcards

check box to activate this feature.

For example, the wildcard feature causes *.yourhost.dyndns.org to be aliased to the same IP

address as yourhost.dyndns.org.

8.

Click

Apply

to save your configuration.

Figure 5-2

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Customizing Your Network Settings

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Configuring the WAN Setup Options

The WAN Setup screen lets you configure a DMZ (demilitarized zone) server, change the

Maximum Transmit Unit (MTU) size, and enable the wireless router to respond to a ping on the

WAN (Internet) port. From the main menu, under Advanced, click

WAN Setup

to view the WAN

Setup screen.

The WAN Setup fields are described in the following table:

Figure 5-3

Table 5-2.

WAN Setup Settings

Setting

Description

Disable SPI Firewall

The Stateful Packet Inspection (SPI) firewall protects your network and

computers against attacks and intrusions. A stateful packet firewall carefully

inspects incoming traffic packets, looking for known exploits such as

malformed, oversized, or out-of-sequence packets. The firewall should be

disabled only in special circumstances, such as when you are troubleshooting

application issues.

Default DMZ Server

This feature is sometimes helpful when you are using some online games and

videoconferencing. Be careful when using this feature because it makes the

firewall security less effective. See the following section,

Configuring Static

Routes

.

Respond to Ping on Internet

Port

If you want the wireless router to respond to a ping from the Internet, select

this check box. This should be used only as a diagnostic tool, since it allows

your wireless router to be discovered. Do not select this check box unless you

have a specific reason to do so.

MTU Size (in bytes)

The normal MTU (Maximum Transmit Unit) value for most Ethernet networks

is 1500 bytes, or 1492 Bytes for PPPoE connections. For some ISPs you

might need to reduce the MTU. This is rarely required, and should not be done

unless you are sure it is necessary for your ISP connection. See

“Changing

the MTU Size” on page 6-6

.

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Setting Up a 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.

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.

The WAN Setup screen lets you configure a default DMZ server.

To assign a computer or server to be a default DMZ server:

1.

Click the

Default DMZ Server

check box.

2.

Type the IP address.

NAT Filtering

Network Address Translation (NAT) determines how the router processes

inbound traffic. Secured NAT provides a secured firewall to protect the

computers on the LAN from attacks from the Internet, but might prevent some

Internet games, point-to-point applications, or multimedia applications from

functioning. Open NAT provides a much less secured firewall, but allows

almost all Internet applications to function.

Disable SIP ALG

Select this feature if you have a SIP (Session Initiation Protocol) telephone or

other SIP base devices, and you want them to communicate with other

people. If you have been unable to build a successful SIP connection,

selecting this check box allows for such a connection without compromising

other SIP ALG (Application-level gateway) firewall settings, such as Disable

SPI Firewall. If you are not using SIP devices, leave this check box

unchecked.

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.

Table 5-2.

WAN Setup Settings

Setting

Description

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