How To Change Ip Address With Comcast

MOONCRICKET · #1 07-28-2008

If you have a router installed after your Comcast modem, then it is easy to get the Comcast system to dynamically generate a new IP address. If you do not have a router, I strongly suggest you get one to have an extra firewall between your computer and the Internet. Most IP addresses given out by the Comcast DHCP system are in a leased mode. This means that if your modem is turned off for several days or more, the IP address goes back to a group of IP addresses to be automatically reassigned to other users. Turning off the modem for short periods of time will not reset the leased IP address because the modem is assigned the IP address based on the original computer's MAC address. Every type of networking hardware has a unique code that is the Media Access Control address or MAC address for short.

Router's also have a MAC address. Once this MAC address is synced up with the cable modem, the Comcast DHCP system assigns the IP address to the online outlet. However, if the MAC address is changed, the Comcast DHCP system assigns a new IP address to the online outlet, because it thinks it is a different location. Each computer, with a network card, also has unique MAC addresses. If a person were to hook up a different computer directly to the cable modem, it is likely that a new IP address would be assigned by powering down and then up again the cable modem. However, with a router it is much easier to assign a new MAC address to the router itself. Most routers today have what is referred to as 'clone the MAC address'. This feature allows the user to make the router look like any one of the computers that reside on the premises. Simply logging into the router through a web browser by typing http://192.168.1.1 for Linksys or do a search for Router IP Address to find your particular brand. Then type in the login name and password. Hopefully you changed these for security purposes (and wrote them down) when you installed them from the defaults. This allows you to login and set up the router using the internal configuration program. Find the area where you can clone your MAC address and perform a clone to a new MAC address. Before you clone the MAC address, write it down. This is so you can put it back to the original if you need to. Once the cloning is done, then you can try a release IP address and renew IP address in the router's programming structure. This sends a release the lease to the Comcast DHCP and then renews with a new IP address. Suggest powering down the cable modem, router, and computer at this time. Then re-power everything back up and you should have a new IP address.

Last setp is to check your ip address:
What Is My IP Address? - IP Address Lookup, Bandwidth Speed Test, IP Info, plus more

Good luck.

**aspkin** · #2 07-28-2008

Thanks MOONCRICKET, another how to change your IP address thread. I hope it helps someone.

coopster72 · #3 07-30-2008

Nice Post Mooncricket! I do the same thing with Time-Warner cable only I use two NIC cards in my main pc in place of the router.

For some reason spoofing the MAC ID in my router does not change the IP. However spoofing the NIC card's MAC ID does though, very strange. I've tried three completely different routers and I still cannot get my IP to change.

So here is what I figured out. You're going to love this.
- I have an ethernet cable from the cable modem to the 1st NIC card.
- I have internet sharing enabled with the 2nd NIC card and a Static IP of 192.168.11.1 on the 2nd NIC card.
- I have another ethernet cable from the 2nd NIC card to any LAN port on the router
- I have the router setup as access point only (with WPA). I disabled DHCP and assigned the router a Static IP of 192.168.11.254
- This carries the signal over to my laptop which is manually assigned 192.168.11.2
- my iphone is .3, my wife's is .4, and so on

Now that I've explained the setup let's begin the IP switch process (takes less then a minute).
- I first turn the power off on the modem. Since I'm lying in bed with a beer in my hand I have this remote keychain that turns the power on and off in the other room

and my cable modem is plugged into that. Here's a link of what I purchased Wireless Remote Control Power Outlet Indoor On/Off Switch with 100 Feet Range
- I then VNC Download UltraVNC 1.0.4 RC16 - FileHippo.com from the laptop to my desktop
- I use MAC Makeup Mac MakeUp - MAC Address spoofing tool to spoof the MAC ID of the 1st NIC card. I do it twice, once with the "auto on/off" checked and once with it unchecked.
- Then I disable the 1st NIC card
- I turn back on the cable modem with my spiffy remote
- I wait about 30 seconds and re-enable the 1st NIC connection
- Wait another 30 seconds and check your ip IP Burger - What is my IP Address? Find Your IP Address!

I have to do it exactly in that order or else it doesn't work.

The trick is to see if you can use the same 2 or 3 MAC ID's to keep the same 2 or 3 IP addresses. I keep mine for weeks as long as I log into each one every day.

vipers1999 · #4 09-04-2008

The comcast method worked perfect for me. Thanks!! That will definitely come in handy.

ParkAvenueChic · #5 09-06-2008

Ok, I have a problem, we have comcast internet but we have an apple airport extreme router. Is there a way to change the IP address with that?

moomooj · #6 09-17-2008

Thank you so much for the tips. I just tried it and it worked. However, here's a question: I use Netgear router, which does not let me "clone Mac" (at least I didn't see it). Instead, it gave me three options: 1. use the default Mac; 2. Use computer's Mac; 3. Use a Mac address specified by Netgear. So does this mean I can only change my mac address three times, and I can only have 3 different IPs. Any help is appreciated. Thank you in advance!

Quasi_Mojo · #7 09-17-2008

What is the model number of your Netgear router?

moomooj · #8 09-18-2008

It's WPN824 V2. Can I make up mac addresses?

Quasi_Mojo · #9 09-18-2008

moomooj, according to your wireless router's User Guide, this is what you should do to clone your computer's MAC Address (after you change the computer's MAC Address):

Quote:

Some cable modem ISPs require you to use the MAC address of the computer registered on the account. If so, in the Router MAC Address section of the Basic Settings menu, select Use this Computer’s MAC Address. The router will then capture and use the MAC address of the computer that you are now using. You must be using the computer that is registered with the ISP. Click Apply to save your settings. Restart the network in the correct sequence.

Here's a thread you might want to read: http://www.aspkin.com/forums/ebay-tr...uter-uses.html

As far as I can tell, you can have unlimited MAC Addresses. IP Addresses are issued from your ISP, so you'll want to keep track of which IPs you are using for each eBay/PP account.

Caseyjr86 · #10 09-18-2008

Quote:

Originally Posted by moomooj

Thank you so much for the tips. I just tried it and it worked. However, here's a question: I use Netgear router, which does not let me "clone Mac" (at least I didn't see it). Instead, it gave me three options: 1. use the default Mac; 2. Use computer's Mac; 3. Use a Mac address specified by Netgear. So does this mean I can only change my mac address three times, and I can only have 3 different IPs. Any help is appreciated. Thank you in advance!

I have a netgear also and your in the right spot, we can't "clone". I know the first two one is the router, the other you can bypass it with your computers card mac address.. I also see the custom option as was wondering that also.. Let me know if you try it, If I get around to it I'll post if it worked with a "made up" mac address.

BooMer · #11 09-30-2008

Here is the Link to the Original Post that I made to change your IP for your Router connected to your Cable Modem. It will work for any brand of Router. It was my First post.

Changing your IP Address through your Router