How do I force IP's? Complicated...

[sygyzy]

Okay I have a Windows Me machine (A) and a Win2k machine (B). Originally A had the IP 1 (for the sake of simplicity). I just bought a new network card for B but since it was better than the one A had, I gave A's to B and the new one to A. Apparently the IP on my school's LAN are assigned by network cards (MAC addresses I assume). I know this because despite plugging B into the RJ45 port in my living room, it takes A's IP of 1. And A now has a different IP - 2. The IP's at my school are technically not static but they might as well be. I have never seen them change, ever. So I know IP's 1 and 2 are free. Since I have an FTP server, I'd like A to use 1 like it did originally. So I went to my network settings to force A to take 1 and B to take 2. Well it didn't work. I get these IP conflict errors. I only typed in the IP field. I don't know what to put for subnet or any of the other fields. This shouldn't be against school rules or anything because I am taking 2 IPs that are designated to me anyways, but just switching them. Any clues?

 

[spidey07]

I don't know if you school is using DHCP reservations for everybody. That wouldn't mac much sense. Probably just using regular DHCP and the IP followed the MAC address. Once you obtain a DHCP lease, it is yours for the entire lease duration and will follow the MAC.

Do me a favor, use winipcfg on the 98 box and also "ipconfig/all" for the 2000 box and read every setting you have. Of importance here is the LEASE DURATION. I normally set leases to 7 days or even a month depending on the environment.

Even in DHCP environment your IP address doesn't change.

 

[sygyzy]

Here is the info!

Windows Me (AKA BOX A):

IP Address 128.111.183.114
Subnet Mask 255.255.255.0
Default Gateway: 128.111.183.1
DHCP Server: 128.111.30.12
Primary WINS Server: 128.111.30.12
Lease Obtained: 03 06 01 9:28:30AM
Lease Expired: 03 06 01 9:28:30AM

Windows 2000 (AKA BOX B):
DHCP Enabled. . . . . . . . . . . : Yes

Autoconfiguration Enabled . . . . : Yes

IP Address. . . . . . . . . . . . : 128.111.183.98

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 128.111.183.1

DHCP Server . . . . . . . . . . . : 128.111.30.12

DNS Servers . . . . . . . . . . . : 128.111.30.3
128.111.1.2
128.111.1.1
Primary WINS Server . . . . . . . : 128.111.30.12

Lease Obtained. . . . . . . . . . : Tuesday, March 06, 2001 5:34:05 AM

Lease Expires . . . . . . . . . . : Tuesday, March 06, 2001 5:34:05 PM

 

[spidey07]

looks like a 12 hour lease. But I was thinking and am not sure if you could selectively get the IP that you want.

Try this: boot both computers and release the IP from both. use winipcfg on 98 and ipconfig /release on 2000. Then wait twelve hours. Click renew on the 98 box and see if you get a different address. (or just turn both off for 12 hours and turn the 98 box on first...wait for 5 minutes after it has booted then boot 2000)

I know it sounds stupid, but it is the best I can think of. Maybe you can call the network admin dept and see if they'll setup a DHCP reservation. This way the 98 box and ONLY the 98 box can lease a particular IP. The 2000 will just grab what it can.

 

[sygyzy]

Thanks for your help, any other takers?

 

[cavingjan]

Without access to the DHCP server, your only shot is releasing the IP address. Or switch your nics back to their original homes. Why did you switch? Specific reason like a problem or just something new.

 

[Ladi]

Try releasing DHCP lease from A and B, then renewing from B, then A.

If you need to be able to keep the same IP for each machine to be able to access it, you may want to look into signing up for a dynamic DNS service (like dyndns.org, although many others exist) and updating it any time your IP changes (this can be done automatically).

~Ladi

 

[DieselMan]

PMC4EVER and I once played around and found a solution to your problem. You need LINUX or some UNIX distribution, and what you basically do is manually change your MAC address for your Network card; I have never found a way to do it under Windows NT but I am sure there's some hacks around (you may be able to edit VMWare's MAC address settings to a "real" MAC address, but I haven't played around with it for a long time).


Here's how you do it in Unix/Linux:

/sbin /ifconfig eth0 hw ether 00:00:00:00:00:00

Assuming eth0 is the network card you want to use, just change the MAC address to the desired MAC address (the one from your other machine; you have to unplug the "real" NIC that has the MAC you're trying to hack, or else you'll get a network hardware conflict).

I don't know if you realize this, but if you have a laptop, you can pretty much go just about anywhere (many schools and libraries), and "log" your machine in using this trick...

 

[sygyzy]

Thanks for your help guys. I think I'll just take the addresses they gave me. I don't want to do the DHCP since it is not that important to me for my users to have a constant IP to connet to. It's their loss if they don't ask me when there is a change. I also really don't want to install a whole new OS just to get an IP back. Thanks so much for the help. I appreciate it.