# Could IP address conflict indicate hacking?



## naomikay (Apr 12, 2013)

Hi, my mum's laptop/netbook is displaying the following message: 
'Another computer on this network has the same IP address as this computer'. 
I realize that this is often a general problem that can occur, but is there any chance her computer system has been hacked, and how would we be able to find out whether this is a possibility? If so, how could this be done and what could be done about it? 

I know this sounds slightly far fetched, but the reason we are asking is that she has very recently come out of a year long relationship with a man who was often paranoid and unstable (accusing her of cheating with no rational reason to think so, threatening suicide when she had tried to break up with him, etc.), knew some dodgy people, and was very computer savvy. He had, in the past, also hidden cameras in the house while they were together, and broken into my mum's email (claimed that he knew her passwords by watching her type them but my mum is skeptical). 

We are worried about contacting the police, as in my area they are renown for not taking enough action before something major happens. He is also a prison officer, which has helped him get off charges in the past (minor incidents such as dangerous driving where other people have been injured and it has been acknowledged that the accidents were his fault), he has the same protection as a police officer, and is actually friendly with a lot of his past inmates who he has threatened people with in the past. 

I live in the UK, if that has any relevance at all.


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## lunarlander (Sep 22, 2007)

How many PCs are in the same home network? 

This error is usually a result of a DHCP hiccup. And usually a reboot will fix the problem. Also try powering off the router and powering it on again. If that does not fix the problem. then assign a static ip address to that PC, by going to Control Panel > Network and Sharing Center > Local Area Connection > Properties button > click on Internet Protocol v4, and click on Properties button > select Use the following ip address. Type in an ip address that matches your network. 

Your network's address can be found by opening up a command prompt and typing in the "ipconfig /all" command. Usually in the form of 192.168.0.x. or 192.168.1.x . Make up the x part with a number less than or equal to 254. The subnet mask is 255.255.255.0 and the gateway address is the same as given in the ipconfig command. Also use the same DNS server addresses as given by ipconfig.


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## Watiod (Apr 19, 2013)

Actually nope.. If you have a IP conflict means 2 of your gadgets(PC/laptops/netbooks) used same IP. how is it? your router provide IP to your gadgets which sometimes send double IP. just repair it in your network icon or reset your router.. ok..


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## zx10guy (Mar 30, 2008)

Umm....not really. A DHCP server will never "knowingly" issue duplicate IP addresses. A DHCP server has an internal database where it keeps track of IPs it has issued. Where you usually get IP conflicts is if a device was taken off the network and not placed back on the network for some time during the lease renewal period. During this time, the DHCP server would assume the IP is available as the device it was assigned to has not performed a lease renewal. So it issues this IP address to a device requesting an IP. And if during this time, the previous device gets turned on and placed back on the network you now have an IP address conflict issue.

The proper way to prevent this from happening is if you know a device is going to be off the network for a while is to perform an IP release. In Windows from a command prompt, you would issue the following command: ipconfig /release

As a side discussion, more advanced DHCP servers can be configured to ping an IP address it is looking to assign to a DHCP client. If the DHCP server gets a reply, it knows that IP address can't be used and moves to the next available IP to issue out to the client.


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## TerryNet (Mar 23, 2005)

Does your mum's computer have a static or dynamic (Dhcp) address?

Does any device on the network have a static IP?


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