IP Renew Trouble 2

[mikey62]

I have comcast cable modem using XP through a linksys router. My problem is when I do a dhcp renew in the router I keep getting the same IP 24.14.xxx.xx as an example as my wan ip. the router then dispenses to my nic a 192 address which is the norm. However when ever I release renew in the router I keep getting the same Ip! I called comcast and they could do nothing. I also hardlined directly to the cable modem using my laptop as a direct connection = I rec a different IP of 67.173.xx.x as an example. but when I do a ipconfig /release and then I renew I still get the same 67.173.xx.x Ip from comcast. so?

does comcast have ip's set aside to authenticate with my mac address on my machines? even though they supposedly use dhcp? the tech could not believe it but understood. my problem is I don't want a static IP but seem to have one!

is my situation a common one?

any ipspoofing ware out there I can use to get a new IP or at least hide behind something to be safer?

any help appreciated or any sites welcome.

thanks!

Mikey

 

[bcastner]

The behavior you are seeing is perfectly normal. To truely force a different WAN IP (I seriously doubt it is tied to your MAC in any formal way):

Unplug (do not use if available the on/off switch) the modem.

Wait at least 35 minutes. Overnight is best. (34 minutes is the typical MAC authentication sweep for cable systems).

Plug in the modem. Restart your machine.

 

[mikey62]

Thanks B. I will try your method. I did not know about the modem sweep issue. Is it still possible that I will get my same IP back after maybe waiting a day or so?

Mike

 

[bcastner]

It is possible, yes.
But you are fighting the good fight to draw from their IP block a different one.

 

[mikey62]

kinda interested in this mac sweep authentication thing. does the cable sys sweep for the mac of the modem or the router or the pc? in other words am I using 3 nic cards in a sense to communicate with the "cloud" ex. pc 1 nic next router 2nd nic next router connected to cable modem 3rd nic?
.....man that is a lot of st nic's!

Mike

 

[bcastner]

It sees the MAC of the device connected to the modem. This is why many consumer class modems offer a freature to "clone" or manually assign a MAC. My personal preference would be to change ISPs, but you can still find dinosaur ISPs that will refuse to allow a home LAN. You take the MAC address of your principal PC (an IPCONFIG /All will reveal this as the 'Physical Address' of you network adapter) and plug that into the configurable MAC setting of the router.

This works perfectly, but my preference would be to change ISPs if your service agreement does not permit a LAN sharing of the internet access.

 

[AvayaNovice]

Hmmmmm, I might be able to help with this.

I work for Charter Communications...

We actually use an 8 hour window for IP lease expirations. Secondly, your Ip address IS tied to your MAC address. The only time it WILL change is if the MAC address table for your particular router is rebuilt, and your place is changed, otherwise, you'll keep the same IP for long periods of time.

It is DHCP still, as we are issuing the address.

 

[mikey62]

Man! I love this IP stuff. George Orwell = eat your heart out because Big Bro is here!. Even though DHCP because they issue etc...

I believe in Mel Gibson conspiracy theory movie to make it still more fun.

again thanks for replying and any more info please forward here. very knowledegable all!
any cool links?

thanks again I like this site. Learning is fun.

Mikey