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4.5 DHCP Server

The settings of TCP/IP environment include Host IP, Subnet Mask, Gateway, and DNS

configurations. It is not a simple task to correctly configure all the computers in your LAN

environment. Fortunately, DHCP provides a rather simple approach to handle all these

settings. The DI-704 supports the function of DHCP server. If you enable the DI-704’s

DHCP server and configure your computers as “automatic IP allocation” mode, then when

your computer is powered on, it will automatically load the proper TCP/IP settings from the

DI-704. The settings of DHCP server include the following items:

1.

DHCP Server

: Choose “

Disable

” or “

Enable

.”

2.

Range of IP Address Pool

: Whenever there is a request, the DHCP server will

automatically allocate an unused IP address from the

IP address pool

to the requesting

computer. You must specify the starting and ending address of the IP address pool.

3.

Domain Name

: Optional, this information will be passed to the client.

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4.6 Virtual Server

The DI-704’s NAT firewall filters out unrecognized packets to protect your Intranet, so all

hosts behind the DI-704 are invisible to the outside world. If you wish, you can make some

of them accessible by enabling the

Virtual Server Mapping

.

A virtual server is defined as a

Service Port

,

and all requests to this port will be redirected to

the computer specified by the

Server IP

.

For example, if you have an FTP server (port 21) at 192.168.123.1, a Web server (port 80) at

192.168.123.2, and a VPN server at 192.168.123.6, then you need to specify the following

virtual server mapping table:

Service Port

Server IP

Enable

21

192.168.123.1

V

80

192.168.123.2

V

1723

192.168.123.6

V

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4.7 Special AP

Some applications require multiple connections, like Internet games, Video conferencing,

Internet telephony and so on. Due to the firewall function, these applications can not work

with a pure NAT router. Special Applications enables some of these applications to work

with a NAT router. If Special Applications is still insufficient to allow an application to

function correctly, try DMZ host in the

Misc Items

options.

1.

Trigger

: the outbound port number the application issued first.

2.

Incoming Ports

: when the trigger packet is detected, the inbound packets to the

specified port numbers are allowed to pass the firewall.

The DI-704 provides some predefined settings in the gray pad on the bottom of the web page.

Choose the

Popular application

and click

Copy

to copy the predefined setting.

Note! At any time, only one PC can use each Special Application tunnel.

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4.8 Access Control

Access Control allows you to assign different access rights for different users. First, you

have to divide users into different groups. Users are identified by their IP addresses. You can

assign the members of Group 1, 2 and 3. The others are all members of the Default Group.

Second, you have to assign the access rights of each group. Access rights can allow or block

users to access specified TCP and UDP ports. For example:

Group

Members

Access Right

Comments

Default

-

Allow ()

No access right (allow nothing)

Group 1

100-199

Allow (25,53,80,110)

Can browse(80), receive(110)

and send(25) email only

Group 2

50-99

Block (21,119)

Cannot read net news(119) and

FTP(21) only

Group 3

1-9,20

Block ()

Fully access (block nothing)

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4.9 Misc Items

1.

IP Address of DMZ Host

: DMZ (DeMilitarized Zone) Host is a host without the

protection of firewall. It allows a computer to be exposed to unrestricted 2-way

communication. Note that, this feature should be used only when needed.

2.

Remote Administrator Host

: In general, only Intranet users can browse the built-in web

pages to perform administrative tasks. This feature enables you to perform

administrative tasks from a remote host. If this feature is enabled, only the specified IP

address can perform remote administration. If the specified IP address is 0.0.0.0, any

host can connect to the DI-704 to perform administrative tasks. When this feature is

enabled, the web port will be shifted to 88.

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