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TOPIC: all PC are having IP conflict , many are having same MAC add

all PC are having IP conflict , many are having same MAC add 12 years 1 month ago #4541

  • giggs
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HI ,
Does anyone having this porblem before?
"every machine in the building reported an IP Address conflict with the same MAC address"
How to slove it?

George
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Re: all PC are having IP conflict , many are having same MAC add 12 years 1 month ago #4547

  • Chris
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Now here's a problem I've never come accross!

All computers are reporting an IP address conflict? It sounds more like a worm or virus problem rather than an actual conflict, unless your running a dhcp service and something wired is happening with it;

Have you tried scaning a few pc's for virus or trojans? I'd advise you also run a packet sniffer and watch the traffic on the network, see if you can identify any wired behaviour.

Let us know how the network is setup, IP addressing scheme, services running (e.g dhcp, dns e.t.c) and anything else you think could help us help you!

Cheers,
Chris Partsenidis.
Founder & Editor-in-Chief
www.Firewall.cx
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Re: all PC are having IP conflict , many are having same MAC add 12 years 1 month ago #4556

  • giggs
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THanks for your reply , CHris!.
Below is the arp result I got when I am having the IP conflict problem.
Many PC are having the same MAC 00-0c-f1-1d-45-01 and even my router too(10.1.1.254)!
I do have a DHCP server but all the IP below are static IP.
I'm still not sure the source of the problem but I know that the problem start when we are started using wireless lan.
And most of the case, the problem MAC address is belonged to notebook with both wireless and wire connection.

C:\Documents and Settings\george>arp -a


C:\Documents and Settings\george>arp -a

Interface: 10.1.6.11 on Interface 0x1000003
Internet Address Physical Address Type
10.1.1.5 00-0c-f1-1d-45-01 dynamic
10.1.1.127 00-0c-f1-1d-45-01 dynamic
10.1.1.129 00-50-8b-6d-19-08 dynamic
10.1.1.254 00-0c-f1-1d-45-01 dynamic
10.1.5.5 00-01-e6-b5-79-59 dynamic
10.1.6.7 00-01-02-96-04-0d dynamic
10.1.6.25 00-0c-f1-1d-45-01 dynamic
10.1.6.32 00-0c-f1-1d-45-01 dynamic
10.1.6.54 00-0c-f1-1d-45-01 dynamic
10.1.10.241 00-01-02-96-04-0d dynamic
10.1.10.242 00-10-5a-72-5c-78 dynamic
10.1.10.254 00-0c-f1-1d-45-01 dynamic

C:\Documents and Settings\george>arp -a

Interface: 10.1.6.11 on Interface 0x1000003
Internet Address Physical Address Type
10.1.1.5 00-0c-f1-1d-45-01 dynamic
10.1.1.127 00-0c-f1-1d-45-01 dynamic
10.1.1.129 00-50-8b-6d-19-08 dynamic
10.1.1.254 00-0c-f1-1d-45-01 dynamic
10.1.5.5 00-01-e6-b5-79-59 dynamic
10.1.6.7 00-01-02-96-04-0d dynamic
10.1.6.25 00-0c-f1-1d-45-01 dynamic
10.1.6.32 00-0c-f1-1d-45-01 dynamic
10.1.6.54 00-0c-f1-1d-45-01 dynamic
10.1.10.241 00-01-02-96-04-0d dynamic
10.1.10.242 00-10-5a-72-5c-78 dynamic
10.1.10.254 00-0c-f1-1d-45-01 dynamic

C:\Documents and Settings\george>arp -a

Interface: 10.1.6.11 on Interface 0x1000003
Internet Address Physical Address Type
10.1.1.5 00-0c-f1-1d-45-01 dynamic
10.1.1.127 00-0d-60-78-e4-9a dynamic
10.1.1.129 00-50-8b-6d-19-08 dynamic
10.1.1.254 00-0c-f1-1d-45-01 dynamic
10.1.5.5 00-01-e6-b5-79-59 dynamic
10.1.6.7 00-01-02-96-04-0d dynamic
10.1.6.25 00-0c-f1-1d-45-01 dynamic
10.1.6.32 00-0c-f1-1d-45-01 dynamic
10.1.6.54 00-0c-f1-1d-45-01 dynamic
10.1.10.241 00-01-02-96-04-0d dynamic
10.1.10.242 00-10-5a-72-5c-78 dynamic
10.1.10.254 00-0d-60-78-e4-9a dynamic


C:\Documents and Settings\george>arp -d *

C:\Documents and Settings\george>arp -a

Interface: 10.1.6.11 on Interface 0x1000003
Internet Address Physical Address Type
10.1.1.127 00-50-da-0d-dd-1a dynamic
10.1.1.129 00-50-8b-6d-19-08 dynamic
10.1.6.25 00-04-75-ca-9e-88 dynamic
10.1.10.254 00-50-fc-ab-ab-9c dynamic
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Re: all PC are having IP conflict , many are having same MAC add 12 years 1 month ago #4580

  • Jack
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Try: ipconfig /renew and arp -d see if by chance that helps??


Good Luck,
Jack Burgess,
Firewall.cx Staff
News Editor / Forum Moderator
www.jacksjunk.com
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Re: all PC are having IP conflict , many are having same MAC add 12 years 1 month ago #4581

  • giggs
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Thanks for your reply Jack, your suggestion can slove the problem.
But I cannot do it for 300 machines at the same time.
Also, it 's very annoying and it will cost all the network connection down for a few minutes. And it happen 1 to 2 times a week..
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Re: all PC are having IP conflict , many are having same MAC add 12 years 1 month ago #4586

  • sahirh
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This is something really wierd.. you said its all static IP's right ?
hmm that rules out problems with the DHCP scope...
Sahir Hidayatullah.
Firewall.cx Staff - Associate Editor & Security Advisor
tftfotw.blogspot.com
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