How to Use ADSL Modem as WiFi Router

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I have a ADSL router with wifi.now i have purchased cable internet and i want to use my existing ADSL modem as a wifi router. The modem is this one http://www.pcwintech.com/screenshots-beetel-450tc1-beetel-firmware

i get the idea that we have to disable ADSL/DHCP on it, but i want an exact guide/option/solution for the same.
Thanks

Update:
i am not able to figure out how to disable the integrated ADSL modem, when i directly connect the cable to my computer i get a static ip address and a default gateway assigned. So what i did was to disable DHCP on the modem, and configure it's static ip to the IP which was assigned to my laptop. I then connected the cable to one of the RJ45 ports of the modem, but i don't get it to work still. When i open a page i get the Figure 1 and Figure 2 has the settings.

alt text

Updating details for the new setup:
I don't have a cable modem, all i was provided with was a LAN cable by the provider which i directly plugin into Ethernet port of the laptop, and it assigns me a static ip address, default gateway and DNS which is always same everytime. Will anything change now?

Update:
I believe the lan cable is connected to a box which in turn negotiates with the main IP. The provider confirmed to me that the ip remains static and i get it assigned as
124.123.163.164/255.255.192.0
Default Gateway:124.123.168.1
and some DNS entries.

I now am thinking of buying a Non ADSL Wifi router, which can solve my problems i suppose.

Best Answer

The provider confirmed to me that the ip remains static and i get it assigned as 124.123.163.164/255.255.192.0 Default Gateway:124.123.168.1 and some DNS entries.

Because this is a very different situation than what I originally thought we were talking about, I've completely replaced my previous answer. If anyone is curious what I deleted, the previous revisions are still out there, of course.

@Anirudh

While I'm not very skilled at such things, I did try to do a whois.net lookup of the IP they gave you, 124.123.163.164. It appears to be registered with "Asia Pacific Network Information Centre" in Milton, Australia. But the contact info points to "Beam Telecom", "Beam Cable System", and/or "Beam Telecom Pvt Ltd", 8-2-610/A, Road No - 10 Banjara Hills, Hyderabad, India.

The subnet mask they gave you, 255.255.192.0, implies that your IP and the 16,382 (?) other IPs in the range 124.123.128.1 to 124.123.191.254 are on the same subnet of the larger Internet. In other words, all these public IPs are in some sense "local" to your IP. That's a relatively big subnet which I find surprising. It makes me wonder how their network actually functions. Oh, well.

What you appear to have is a one static IP which is on the public Intenet. In other words, you don't have a local LAN at all, just an IP which gives you direct, unfiltered ... and unprotected! ... access to the Internet. This would also mean there is no DHCP server so you would need to manually enter the IP configuration data ... the IP address, the default route, and the DNS servers ... into the one computer you could connect to the Internet using this IP address.

So, yes, I would recommend you obtain another router and put it between you and the free rolling chaos which is the unfiltered public Internet. Put your systems on a local LAN behind a router which uses (at least) NAT, SPI and DHCP.

You would then enter the one static IP you were given as the WAN information for the router, connect the router via its WAN port to the ethernet port from your ISP, and then connect your systems to the router LAN ports. Your computer(s) would then have local LAN IPs assigned to them by the router's DHCP.

I would also recommend ignoring the DNS servers your ISP gave you and going with one of the public DNS providers such as OpenDNS or Google DNS. Maybe it's just me, but I like having even a small bit of extra filtering between me and the hoards of malicious sites out there these days.

As for the router itself, there are two ways you could go.

You could, as you mentioned, obtain a home router which includes wireless.

But you could also use a wired home router, connect your Beetle to it, and then use the Beetle for wireless access. This is what I thought you were trying to do in my previous answers.

I mention this as an option because you might know someone who has a wired router they no longer use which you could re-purpose. Depending on your situation, it might be a quicker or cheaper solution for you.

The important thing is to get a router, either wired or wireless, which gives you some isolation from the public Internet by using NAT plus "stateful packet inspection" (SPI) to create your own LAN. The router's DHCP would also save you the hassle of entering static configuration info and would allow multiple computers to use/share your Internet access at the same time.

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