IP conflicts, details inside

Ok, my boss is running an IBM Lenovo laptop on a docking station. He wants wireless and the ethernet cord in and active. He gets an ip conflict everythime he connects. He had a dhcp reservation for both his wireless IP and wired IP. I have since removed the reservation on the wireless as it wasnt needed.
We are running WINS and DHCP and DNS due to the cobbeled state of our network. His Netbios name was attached to 2 different IP's, which is what i thought was cuasing the conflict. I have tried to mimick my settings tohis, as I do not get a conflict, but to no avail.
I can't find much on setting WINS for a mixed network, and I really don't have a ton of experience with all of this being 6 weeks on the job and fresh out of college. His ip's in a ipconfig /all reveal two seperate ip's. When I run ntbstat -a i get two ip's, but both are associated to his Wireless Mac address. Also in ipconfig /all his wireless shows up first then his ehternet nic (which is different from al other machines here, but i cant find anything about it or I am search the wrong key words)
Can anyone point me in a direction? I am trying to install a wireless controller and AP's (which I know nothing about of course, but more than the vendor) and also configuring Groupwise 6.5, so him bothering me with an Ip conflict is killing me.
Thanks

An ip conflict means that more than one machine (or nic) has the same ip address.

You say you are using DHCP. It sounds like either the DHCP server assigned one ip addresses to two different NICs (different mac addresses) or the DHCP server assigned it to one NIC and another user statically assigned the same ip address to their NIC.

If it were me, I'd make note of the ip addresses being used on the machine reporting the conflict.
(BTW: did you statically assign these addresses? or were they assigned via DHCP?)

Then take that machine offline and go to another machine on your network and try to ping it or resolve the other host. Then you can find out if that machine was statically assigned and change it back to DHCP.

The DHCP server *should not* have assigned one ip address to two different mac addresses. You can check the DHCP server to see who the lease belongs to.

Also, if you did assign one of them statically... that is ok, as long as it is outside of the DHCP scope.

Meaning, if you're DHCP server assigns addresses in the 192.168.0.2-50 range, don't statically assign one of those addresses. Use 51-254. etc.

The guy before me set up DHCP reservations. I will have to look more closely, but in my active ip's list from the DHCP server i just see the ip once. I'll muddle through it, so maybe I can move on to other things.....thanks!

His netbios name in WINS shows it as a workstation with an IP address and then as a fileserver with his wireless ip address. Is this the conflict? But this seems to be the case for 2 other laptops if i enable wireless while they are plugged in. All 3 laptops have DHCP reservations on the ethernet NIC, but not the wireless ip's

No, you should only have an ip conflict if two nics are assigned the same ip on the same subnet.

One machine have many names or aliases in dns or whatever.
Those are just means to find the machine.

First thing I would do is mark down the IP(s) that the machine is using.

Then remove it from the network (both wired and wireless).

Try to ping those addresses to see if they respond.

If they respond, then there is another machine with the same ip address and thats why you see the conflict. Go to that machine and see if it is statically assigned. If so, then change it to DHCP.

Is it possible that the former admin assumed that the person with the laptop would be using one or the other (wired or wireless) and forced the same ip to both NICs?

BTW: Why do they need both wireless and wired at the same time?

Because he is my boss.......
honestly, I have reading so much on VLANS and Meru's wireless mesh system to get it up and running before we get busy, and setting up Active Directory, this ip conflict just pisses me off. I have no clue why he wants them both on at the same time. I asked that around the same time I got my head chewed off for mentioning we needed IDS in our network. He yelled and yelled and said we were secure. The following week i brought 7 2003 servers up to Service Pack 1. So, I have a chip on my shoulder at this point with how he goes about things.
And any time I do anything I need to explain it to him like a 2 year old so he can "learn" as he says.
Is there a command line command I can issue to list ip's? Because the current leases i see in DHCP show his ip's once only. But it may be more to it than that.
Thanks

fruastrate junior entry level sys admin <sr sys admin is on vacation>

kill me now please!

An arp -a 10.10.xx.xxx reveals just one Mac

nbtstat -a 10.10.xx.xxx reveals something unique to his system two (00) listings and one <1e>


Name Type Status
---------------------------------------------
MCLENOVO <00> UNIQUE Registered
ADMIN <00> GROUP Registered
ADMIN <1E> GROUP Registered

netbios-ns (137/tcp)


Synopsis :

It is possible to obtain the network name of the remote host.



Description :

The remote host listens on udp port 137 and replies to NetBIOS
nbtscan requests.
By sending a wildcard request it is possible to obtain the name of
the remote system and the name of its domain.



Risk Factor :

None



Plugin output :

The following 3 NetBIOS names have been gathered :

MCLENOVO = Computer name
ADMIN = Workgroup / Domain name
ADMIN = Browser Service Elections

The remote host has the following MAC address on its adapter :
00:
CVE : CVE-1999-0621
Plugin ID : 10150

I don't know why you keep messing with netbios/wins/dns. This is an IP problem...

Again, there are two nics with the same ip address. You need to find which two NICs.
Or, simply find an unused IP address outside of the DHCP scop and assign this laptop a new ip.

I turn the laptop off. The ipis not able to be pinged. turn it on, the laptop tells me there is an ip conflict. No event manager record. Etherreal doesnt show 2 dupes of the NIC. WINS Seemed to be what might be giving me the conflict

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He wants wireless and the ethernet cord in and active.

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Why?!?

Quote:

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turn it on, the laptop tells me there is an ip conflict.

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The message should also include the MAC address of the machine that conflicts..

As said by others, forget netbios/wins/dns.. The problem is IP based..

Forget DHCP either.. A DHCP server will never ever give out the same IP to different machines.. A DHCP server will also not issue an IP that's already in use (it pings the IP before giving it to a client)..

I can't give you an answer you would like for why he wants to do it that way. Suffice it to say he is a man challanged by anything that is not a shortcut on his desktop.

That said, I have taken the advice of ignoring WINS and DHCP since I can find no record of an IP conflict in Event logs. I have however found his wired MAC address floating in IPX RIP packets that seem to be generated by an old Netware programs he never removed.

Otherwise, I have no clue. Taking his system offline produces no Ping to the offending IP address. My Dhcp tables dont show it when it goes. nMap wont find it when the laptop is taken off line and a number of testers will laso not pick up anything on the IP WHEN the laptop is taken offline. This is why I am assuming it was WINS or something stupid where the MAc or Netbios was entered twice.
That being said I am at my wits end and ready to kill this guy. And I am not sure where to go next with this.

Thats the story so far, I'll update as i learn more. thanks!

Just a suggestion....

Does your company (or maybe just your boss) want a particular computer to always have the same internal IP every time it connects to the system?

If so, or you are unsure read on....

You can handle this is 2 ways.

1) Assign static IPs/Subnets/Name Servers/Gateways using network setup. This is no good when the user take their laptop home/ to another site/wifi zone as it is highly unlikely that these locations will have the same network address/subnets etc. so ...

2) Use DHCP in network setup so that the laptop gets the correct details from each of the locations visited. At the work location it is possible to setup the DHCP server so that a particular MAC address of a network card gets the same IP every time. If your boss wants the same address using both wired/wireless then is is possible to assign the same IP address to 2 different MAC addresses (One MAC for the wired network adaptor and another MAC for the wireless adaptor)

If you are using option 2 above then if you enable both wired and wireless networking you get an IP address conflict!

What I would suggest is you ask your boss WHY he wants to do this (& if it's the case why he needs to have the same IP address when connected to the work network). Then come & tell us the reasons.

Remember, you should not let non IT people tell you how to solve their IT problem. Get them to tell you the problem so that the expert (you) can provide the solution.

Steve

Quote:

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Forget DHCP either.. A DHCP server will never ever give out the same IP to different machines.. A DHCP server will also not issue an IP that's already in use (it pings the IP before giving it to a client)..

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Possible, but maybe the DCHP server is the one giving the error message of IP conflict & windows is reporting it.

Steve

I have IP reservations on his two IP's One on his wireless xx.xx.xx.01 and one on his wired xx.xx.xx.02
These are taken out of the mix and assigned everytime to them. We assign static IP's b/c the old Network Admin set IP filtering on some systems, so as to allow a few people access and from a specific IP. he comes in in an hour, I'll know more soon b/c this has been a huge waste of my time so far this week.

Are you able to get the wired and wireless working one at a time?
Steve

Yes, one at a time there is no conflict. Run them both at the same time he gets a conflict. I have set my laptop the same, and run it with both on and no conflict. I am starting to wonder if it is becuase there is something funky with his IBM Lenovo, I say this b/c a google of the model shows that some times they do funky stuff

When you boss gets in, connect them one at a time & see if the wireless & wired adaptors are getting the addresses you think they should be:

Quote:

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One on his wireless xx.xx.xx.01 and one on his wired xx.xx.xx.02

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Imagine the following scenario:

A DHCP server is setup to issue 192.168.0.0/24 addresses.

Computer A uses a static IP address (no DHCP), lets say 192.168.0.10.
It also has a firewall running blocking all incoming packets.

Computer B uses DHCP. It does a DHCP request.

DHCP server wants to give out 192.168.0.10. DHCP server pings the address, no response. DHCP server tells Computer B to use 192.168.0.10.

Computer B want to use this address. When it does it pops up a message "IP Conflict".

Viable situation?

The popup on B should include the MAC address of A. If not, check the eventlog of B. Once you have the MAC of A you can look for it on your network and you'll know which computer is the cause of the conflict.


Another thing just popped into my head... How about someone screwing you over?

net send yourboss IP Conflict detected


NB The IPX traffic should be eliminated if unused but it isn't the cause of the IP conflict. TCP/IP and IPX/SPX are 2 very different network protocols and can coexist without any problem.

I am grasping at straws at this point, that is why i brought it up.
As for your scene you described. That scares the hell out of me. Up untill 4 days ago we had 7 servers way behind in updates, we still have no IDS and I have a boss that reamed me when I brought this stuff up.
That said, if I sniff the network for the offending IP address shouldnt I be able to see traffic from "both" systems using the IP? And if that is the case, tracking down the other system may be something to try.
Food for thought, thanks!

Quote:

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Originally posted here by javatard
That said, if I sniff the network for the offending IP address shouldnt I be able to see traffic from "both" systems using the IP?

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Several reasons why not..

First.. Switched network..

Second.. The second machine that tries to use the IP actually doesn't. The IP stack gets disabled when a conflict is detected.

The fact that the NIC cards work independantly suggests it's neither of your ideas SirDice, since you would see the symptoms with either of the NICs working if it was net send and one of the NICs would show the problem if it was another computer with a static IP.

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Yes, one at a time there is no conflict. Run them both at the same time he gets a conflict.

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I'd still like you to check the actual addresses being assigned when using the NICs one at a time.

Steve

Steve

Ok so.....
Log in with just wireless OR wired and there is no conflict. Enable the other and the conflict appears.
Windows - System Error there is an IP address conflict with another system on the network.
Here is the rub, running wired then enable wireless the NIC for the wired is listed as the hardware address it is conflicting with. And vice versa. Seems it is having a conflict with itself???? ;p
that said, ipconfig /all reveals that when only one is enable, the IP is what it should be. Enable both, and both show as the ip's they should be. then disable the first, ip's are as they should and event viewer shows the conflict as gone.
Questions, comments or funny stories???

Short answer :D Tell your boss to use either wired or wireless ;)

If he doesn't want to ask him why on earth he wants both active at the same time..

Quote:

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Originally posted here by javatard
Ok so.....
Log in with just wireless OR wired and there is no conflict. Enable the other and the conflict appears.
Windows - System Error there is an IP address conflict with another system on the network.
Here is the rub, running wired then enable wireless the NIC for the wired is listed as the hardware address it is conflicting with. And vice versa. Seems it is having a conflict with itself???? ;p
that said, ipconfig /all reveals that when only one is enable, the IP is what it should be. Enable both, and both show as the ip's they should be. then disable the first, ip's are as they should and event viewer shows the conflict as gone.
Questions, comments or funny stories???

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Have you checked this just now?

Is the wired NIC x.x.x.02?
Is the wireless NIC x.x.x.01?

Can you post the ipconfig /all (sanitized) for the NICs when in use one at time & screen capture of the error when you try to use both NICs.

Thanks,
Steve

Damn, I think I see the problem. But I know enough to know I dont know everything, so i will post these 2 screen shots

There are more, but I have to go create some new users.....Be back.

All I can see here is the ipconfig for the wireless adaptor.

Can you use cut & paste for this, since it will be easier.

Steve

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Documents and Settings\mgc.ADMIN>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : McLENOVO
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . :
Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Broadcom NetXtreme Gigabit Ethernet
Physical Address. . . . . . . . . : 00-C0-9F-F0-4E-6C
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 10.10.15.60
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . : 10.10.0.1
DHCP Server . . . . . . . . . . . : 10.10.1.13
DNS Servers . . . . . . . . . . . : 10.10.1.13
Primary WINS Server . . . . . . . : 10.10.1.13
Lease Obtained. . . . . . . . . . : Friday, July 14, 2006 8:53:53 AM
Lease Expires . . . . . . . . . . : Saturday, July 22, 2006 8:53:53 AM

C:\Documents and Settings\mgc.ADMIN>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : McLENOVO
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . :

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Broadcom NetXtreme Gigabit Ethernet
Physical Address. . . . . . . . . : 00-C0-9F-F0-4E-6C
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 10.10.15.60
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . : 10.10.0.1
DHCP Server . . . . . . . . . . . : 10.10.1.13
DNS Servers . . . . . . . . . . . : 10.10.1.13
Primary WINS Server . . . . . . . : 10.10.1.13
Lease Obtained. . . . . . . . . . : Friday, July 14, 2006 8:53:53 AM
Lease Expires . . . . . . . . . . : Saturday, July 22, 2006 8:53:53 AM

Ethernet adapter Wireless Network Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : 11a/b/g Wireless LAN Mini PCI Expres
s Adapter
Physical Address. . . . . . . . . : 00-14-A4-61-A9-85
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 10.10.15.219
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
DHCP Server . . . . . . . . . . . : 10.10.1.13
DNS Servers . . . . . . . . . . . : 10.10.1.13
Lease Obtained. . . . . . . . . . : Friday, July 14, 2006 10:32:38 AM
Lease Expires . . . . . . . . . . : Saturday, July 22, 2006 10:32:38 AM

C:\Documents and Settings\mgc.ADMIN>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : McLENOVO
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . :

Ethernet adapter Wireless Network Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : 11a/b/g Wireless LAN Mini PCI Expres
s Adapter
Physical Address. . . . . . . . . : 00-14-A4-61-A9-85
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 10.10.15.219
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . : 10.10.0.1
DHCP Server . . . . . . . . . . . : 10.10.1.13
DNS Servers . . . . . . . . . . . : 10.10.1.13
Primary WINS Server . . . . . . . : 10.10.1.13
Lease Obtained. . . . . . . . . . : Friday, July 14, 2006 10:32:38 AM
Lease Expires . . . . . . . . . . : Saturday, July 22, 2006 10:32:38 AM

C:\Documents and Settings\mgc.ADMIN>

That all looks fine to me.

I'm assuming its for:
Wired Only.
Both Wired & Wireless.
Wireless Only.

Finally can you screen shot the error message and post that...

But I'm running out of ideas.

Steve

You and me both.... it's a windows error. he took the laptop to a meeting so i no longer have it, but it states

Windows System Error
there is an IP conflict with another system on the network

I'm at my wits ends. And I feel real stupid right now. Screen shot attached

Event id: 4199


Microsoft Event ID 4199

Luck..

Wow... that is freaking weird.

Have you tried to unisntall/reinstall the NICs?
(make sure you download the lastest drivers to the PC before you do this.)

dalek,

I had been there. When I remove the system, the IP is not there. I have tried to ping and arp and nbtstat it when the laptop is offline. It just seems like it is internal.
My DNS records show no conflict. My dhcp server shows no conflicts. My Wins is set

Reinstall of the NIC's. No not yet, but that does seem to be the windows thing to do isnt it. i hadnt thought of it because I thought it was something obvious I was missing in settings. <being new and all>

when you switch PC on and it goes to network, all is OK
BUT when you attempt to use network with a second device on same PC it conflicts ??

could it be that the PC has one IP. and whichever protocol starts first will get it ??

so that when the second protocol attempts to access network, the IP has been used, system 'sees' it as a conflict

in reality there is no conflict
you just have a nutsack for a boss

or have I missed something
I usually do :eek:

updating the drivers for both NIC cards solved the problem. Thanks for all your help. Untill the next time I can't figure something out!