I have a few suggestions for you......
FIRST: (consider opt A OR opt B)
- OPTION A: If you are (for the most part) the only one using the DSL line, then don't use a router... Just plug the computer directly into the DSL modem. Next, you would install the client to connect to your DSL account on the PC. this is usually on a CD packaged with your 'installation kit'. While DSL & cable are 'ALWAYS ON' connections, they DO NOT work if you don't have the username & password.
- OPTION B: Leave the router hooked up, but REMOVE the account username & password for the internet from the router when you are done using the net. This way, the router won't be connected to the net, and NO ONE will be able to use it UNLESS then know the username & password for the account.
SECOND: Don't try to block a PC's access by IP address, because it would be too easy to get around. With my D-link router (and I assume yours too) there is a way to enable MAC Address filtering. Each NIC (Network Interface Card) has it's OWN UINQUE MAC address, and not as easy to change as an IP Address. Simply log into your router, Find the MAC filtering tab, and then put in your computers MAC Address (there SHOULD be an option to pick from a list of computer names in a drop-down menu and just select your computer, and it will auto populate the field for you. THEN, change the MAC filter to "ENABLED, and ALLOW only addresses listed." The other options are "OFF" and "ENABLED and DENY addressess listed". You COULD block the MAC addresses of others, but it is MUCH easier to just allow your own, than to have to input a number of different ones.
THIRD: Change the IP address of the router, so that it isn't using the default 192.168.0.1 (or 192.168.1.1 in non D-link routers) IP address that came with the router.
Example: My network is set up in the follow subnet: 10.10.5.24/29
Router: 10.10.5.25 - 255.255.255.248
Etc, etc, etc, for 2 host PC's and a PS2.
FOURTH: Set a password for your router... It is in there in the settings.... My D-Link has TWO usernames & passwords.... 1 is the Admin, and the other is 'user' for a READ ONLY view of the config. MAKE SURE you change the 'user' account name & password so that no one can go and look at you network's IP info.
FIFTH: SAVE THE ROUTER CONFIG ON YOUR COMPUTER, as any bonehead can give you a hard time by reseting it to factor defaults.
Those 5 steps are pretty straigh-forward, and should keep you solo on your internet connection. Please note that there are some ADDITIONAL steps you can take if your router is wireless.
Good Luck
-Zach