Recent Posts ¶

Routed IP on Netgear DG834

Ronald MacDonald <ronald@rmacd.com> v1.0, Thu Nov 08 14:13:39 GMT 2007

Did you know?

The DG834v3 supports Routed IP. Hurray!

Routed IP allows you to use more than one IP address on the same internet connection. Through DSL, for example, a range of IP addresses can be used to address the computers on your internal network.

This method is useful if you wish to run more than one email server from home, for example, or simply wish to use different external IP addresses on each of your computers.

Before you start, bear in mind that this does not work with pre-DG834v3 models. To find the model number, look on the sticker on the bottom of your router, where it should display the version number. V3 models have a yellow faceplate on the Ethernet connections.

A little about IP address allocation

Having signed up to your ISP, you should have been given a static or a dynamic IP. This is a number as quad dotted e.g. 192.168.0.254, and is used to allow you to communicate with the rest of the internet. A dynamic IP address means that this number changes each time you connect to the internet, whereas a static address is reserved for your own use, regardless of how often you reconnect to the internet.

Using Routed IP means you are using more than one IP address at the same time, so this tends to be a static one. Your ISP should provide you with up to 16 IP addresses free of charge. If not, it may be worth pushing them a bit – RIPE policy does not allow an ISP to restrict the number of IP addresses used by a client.

Remember that allocation of an address requires two to be reserved – one for gateway and the other for broadcast. So, let’s say you are given 4 addresses (255.255.255.255/30), two are reserved and unusable, giving one for the router, and only one more for allocation within your network. Not much improvement over the single address (255.255.255.255/32) configuration!

Personally, I have a /28 subnet, giving a theoretical 16 addresses, but only 14 can be used for allocation. Given that 1 is used by the router, that only leaves 13 for the rest of the network. So the rule of thumb is x-3. Have a look at wikipedia.org/CIDR for more information on subnet allocation.

Note

Before you Begin

If you are unsure about any of these stages, be sure to print out a copy, or make a note of the procedures, in case your internet connection does not work again. All changes are reversible, but things can understandably become a bit complicated if you cannot use the internet to complete the rest of this guide.

Login and Backup

This is intended to make a backup of your settings, in the event that your router does not reconnect. Your router will still be accessible, even if the internet isn’t.

Firstly, login to your router, entering the username and password, and proceed to the ‘Backup Settings’ link. Clicking on the ‘Backup’ button saves a file to your computer, which can be used to revert back to the current settings in the event your router goes a bit wonky.

Restoring your settings is as simple as selecting the file via the same page on the router, under ‘Restore Saved Settings from a File’.

Firewall Configuration

The firewall on the DG834 only allows for firewall protection on one external IP address. Therefore, the firewall is useless, and only serves to make using Routed IP very difficult. Remove all the rules, using the Delete button on each rule.

Having completed that, move on to the Basic Settings link on the router, and scroll to the bottom of the page. Here, disable the firewall, which will also disable Network Address Translation.

Switching off both NAT and the firewall is necessary since restrictions in the router’s firmware do not allow Routed IP otherwise.

WAN Configuration

Now, we have to assign the DHCP range provided by the ISP to the network, allowing the computers connected to the router to use Routed IP.

Click on the ‘WAN Setup’ router page, which brings up a list of options. It is a good idea to disable Port Scan and DOS Protection, since as these [should be] handled by the firewall, they sometimes conflict with the Routed IP setup. Additionally, do not specify a DMZ server (all connected clients are effectively DMZ’d).

Assign the router’s address and the DHCP range as follows. It is a good idea to set the address of the router one above the bottom of the range given by your ISP, if only for ease of remembering the address. Additionally, the DHCP server on the router will not typically allow for more than one range (i.e. if the router’s IP is halfway between the bottom and top of your range). So if your range is 70.228.193.150 - 70.228.193.164, set your router IP address to 70.228.193.151.

Before applying the settings, make sure to also change the DHCP settings – otherwise, you will find difficulties communicating with the router. Set the Starting IP Address to one address above your router’s, so for range 70.228.193.150 to 70.228.193.164, set the start address to 70.228.193.152, and for the Ending IP Address, set this to 70.228.193.164. Additionally, before applying the settings, set the router to allow access to the ‘Router Management Interface’ by ticking the box. The port number is used to connect to the router via your web browser, so for port 8080, you access the router via http://70.228.193.151:8080/.

Now, you can apply the router settings. This will change the IP address of your router, and so your computer’s network settings must be updated. With DHCP, it is simply a case of asking the network card to request a new address. Under Windows, this is automatically when you hit ‘repair network connection’, which will reassign a new IP address via the router’s DHCP server. Under Linux, it’s even easier, via:

/etc/init.d/networking restart

Finito!