Erik Østergaard - Bridge mode / DMZ (in English)

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Bridge mode / DMZ (in English)

Multiple routers

Cable modems often have built-in router (possibly also built-in wireless router). Do you still want to use a different router than the one, which is built into the cable modem, you can choose to turn off the router in the cable modem and connect another router. This means change from "NAT mode" to "BRIDGE mode".

If your ISP (Internet Solution Provider) has chosen not to support "BRIDGE mode", the DMZ (DeMilitarized Zone) might be used instead.

Use DMZ to configure an IP (Internet Protocol) address whose ports are directly exposed to the public Internet or to the Wide Area Network (WAN). Demilitarized Zone (DMZ) hosting is commonly referred to as "exposed host," and allows you to specify a recipient of WAN traffic that Network Address Translation (NAT) is unable to translate to a known local PC or second router. DMZ hosting forwards all the ports at the same time to one computer or second router. The purpose of a DMZ is to add an additional layer of security to an organization's Local Area Network (LAN); an external attacker only has direct access to equipment in the DMZ, rather than any other part of the network.

Any computer or second router whose port is being forwarded must have its WAN DHCP (Dynamic Host Configuration Protocol) client function disabled and should have a static IP address assigned to it because its IP address may change when it is using the DHCP function.

DMZ

Connect a separate router to a cable modem with a built-in router

This manual is intended for
Level: [ ] beginning - [X] intermediate - [X] advanced

Note: It can not be expected that your ISP (Internet Solution Provider) will provide support for this setup if it fails to work!

Setup: Internet » Modem/router [from ISP (Internet Solution Provider)] » Second router » Computer (possibly wireless).

Connections: Modem/router is with an Ethernet cable (with RJ-45 connector) Category 6 or better connected from LAN "Ethernet 1" port often yellow connector to the Second router WAN Ethernet port often blue connector. The Second router is then again with an Ethernet cable (with RJ-45 connector) Category 6 or better connected from one of its LAN Ethernet port often yellow connector to one's Computer LAN Ethernet port often yellow connector or Second router is then again connected wirelessly to one's computer.

Access: This manual assumes that access to the Modem/router and the Second router is available via the device's web-based setup, that is, in the URL (Uniform Resource Locator) address field on your browser to write the device's default IP address, such as for example for Modem/router can be: 192.168.0.1, or for example for the Second router can be 192.168.1.1. When entering the IP Address to a device such as a modem or router with a web-based configuration, you are not connecting to the Internet or have to be connected to the Internet. The device has the utility built-in to a ROM chip in the device itself. Your computer must be on the same IP subnet to connect to the web-based utility.

DHCP IP addresses: If the Modem/router by default, for example, has the IP address 192.168.1.1 and its DHCP allocates IP addresses from 192.168.1.10 - 192.168.1.99, the Second router may not use these IP addresses. If this is the case, the setup of the Second router must be changed to avoid using the same IP addresses as the Modem/router. This may in this example be done by giving the Second router IP address 192.168.2.1 and let the DHCP allocates IP addresses from 192.168.2.10 - 192.168.2.99. Note that any changes as far as possible must be made in the Second router and not in the Modem/router.

The assumption in the following instructions is that the Modem/router by default has the IP address 192.168.0.1, and that its DHCP allocates IP addresses from 192.168.0.10 - 192.168.0.128, and that the Second router by default has the IP address 192.168.1.1 and that its DHCP allocates IP addresses from 192.168.1.2 - 192.168.1.254.

Changes in the configuration of the Modem/router:

• Disconnect the WLAN (Wireless Local Area Network): "Wireless Network" is set to "Disable".
• Assign a static IP address for the Second router based on its MAC (Media Access Control) address (Static DHCP / Address Reservation is used to allow a DHCP server to assign the same IP to a specific MAC address). For example, set the "MAC Address": ##:##:##:##:##:##, which is the Second router's WAN MAC address (if it is not displayed, it can be found by logging into the Second router and see in its setup under "Internet") and "Assign to IP": 192.168.0.20 where the IP address is selected within the range that the Modem/router's DHCP allocates.
• Enable DMZ: "DMZ Hosting" is set to "Enable" and "DMZ Host IP Address" is set to 192.168.0.20, the IP address that you selected permanent to assign to the Second router.

Changes in the configuration of the Second router:

• Assign the Second router a static WAN IP address: Change under "Internet" - "Internet IP Address" the option from "Get Dynamically from ISP" to be "Use Static IP Address" and set "IP Address" to 192.168.0.20, the IP address that you selected permanent to assign to the Second router in the setup of the Modem/router. The values "IP Subnet Mask": 255.255.255.0 and the "Gateway IP Address": 192.168.0.1 is not changed.

You must now connect all your other equipment to the Second router, after which it should have access to the Internet. Other changes, such as among other things "Port Forwarding" and "Port Triggering" and other customizations in the configuration of your network must also be made in the Second router.

It should be noted that the various menu items and texts may vary depending on the equipment and product it might be.