Static IP and Router

Question

I have a cable connection coming to my apartment from somewhere in the house. I assume they have a router and a modem and they do like this to grant connectivity to the whole house. To connect, I have to use a static IP address and a netmask like 255.255.255.128.

I am wondering: can I install a wireless router in my flat in order to have wifi connection? Is it enough to buy a router and connect the LAN cable that now I connect to my PC directly to its WAN port and it will propagate the signal via wireless? I assume I have to set the routers IP to the one that I use now on my computer, and the router will take care about generating local IP addresses for the computers connected to it. I would therefore use DHCP settings on all clients of the router.

Do I need to check something specific when buying the router?

Thanks for your advice

Answer 1

Yes you can do this. There are two techniques that you should be aware of though.

First, the Double NAT. This is where your router has a WAN address of say, 192.168.0.100 and a LAN network of say, 10.0.0.0/24. This is the simplest to setup, and will definitely work, but it has a slew of drawbacks. Some stuff just can't work properly this way. Google "double nat" and you'll see a whole bunch of articles.

The better alternative is to put the router into bridge mode. This will make your router more-or-less transparent on the network, you will still connect wirelessly to it, but the DHCP and NATing still occurs on the existing router. Unfortunately, not all consumer routers support this. I have an Airport Express (Apple), it does. Some consumer routers won't show an option called "bridge mode", but may have options to disable both DHCP and NAT, this would work as well.

Answer 2

You should be able to set the wireless router's external interface to the static IP provided to you and set up the wireless LAN to a non-routable subnet which is usually enabled by default.

Answer 3

• Connect WAN port to ethernet modem.
• Configure the router to use the public IP on the WAN interface. (May need to restart modem right after).
• Configure wireless parameters: a SSID (network name) that is unique to prevent confusion, and a WPA2/AES-CCMP encryption key.
• Connect some PC to LAN ports if you want.
• Connect other PC through wifi (you can use LAN and Wifi at the same time for several PC).

Typically DHCP server is enabled by default on the LAN&Wifi side, so you don't have to edit that part.