One of the most common questions and complaints I get about cable broadband is that your IP address will not change. You were banned from your favorite gaming server server, a hacker keeps DoSing your system, or you just got +b'd for being a prick in IRC.
Whatever the reason (lets hope its the 2nd one), you might want to know that it is possible to change your IP. It is a bit trickier than just resetting your router or computer with DSL, but possible nonetheless.
First, lets learn a little bit about DHCP (Dynamic Host Configuration Protocol). Basically, what your router uses that assigns IP addresses automatically. It can also do other things, but right now we are concentrating on IP assignment. Your ISP has the same thing, only on a much wider scale.
The way DHCP assigns IPs, is it looks at the range of IPs it can assign, and then it looks at your MAC (Media Access Controller) address. The MAC address is also known as the physical address. It is basically how different equipment knows it is different from other equipment similar. DHCP looks at the MAC address and says, "Hmm...this router/computer is unique, I will assign it a unique IP." This IP is specific to that MAC address. If you changed your MAC address, your DHCP would change your IP, but if you set it back to what it was, your IP would go back to the original.
So, you may have figured out that to change your IP, you need to change your MAC address. Keep in mind, ISPs with static IP addresses don't exactly love you changing your IP. If you really don't want to take the small risk, don't do it.
So how do you change your MAC address? It is rather simple, actually. First, here is what you need to change.
A MAC address is made up of six octets (xx:xx:xx:xx:xx:xx). The octets of a MAC address each contain a hexidecimal number, so the available characters to use are (0-9) and (A-F). The first three octets are the Organizational Unique Identifier (OUI). This is basicically what the manufacturer uses to identify who made the product. You can use this
to look up the first three octets and see who made the product. The last three octets are completely up to the manufacturer to assign.
A trick your ISP may use, is it make sure the first 3 octets are real, and available to use with the service. So do not change those.
What you want to change is something in the last 3 octets.
Basically, go into your router configuration and change something about the last 3 octets. If your MAC address is 00:A0:40:3F:00:B4, you might want to make it 00:A0:40:3F:01
:B4 . If you don't have a router, changing or spoofing the MAC address of your computer is also possible. You may be able to just change it, by going into your network adapter's properties in the device manager, and clicking the advanced tab. It could be under Network Address, MAC Address, Ethernet Address, etc. If there is no option here to change it, fear not, you can still spoof it with SMAC
Now, you need to just simply reset your modem for this to take effect. If you find it does not work, change another digit of your MAC address. Your ISP will obviously not like it if two systems on its network have the same MAC address, thus having the same IP. So there is a very small chance you might have just changed your MAC address to someone elses. If it still doesn't work, your ISP may have put protective measures on your equipment to make sure the original MAC address would be the only one that can work on it. In this case, you should call your ISP and inform them that you have gotten a "new" router, and give them the MAC address so they can add it into the system.