One IP for several Interfaces

Daniel Thielking Daniel.Thielking at
Sat Feb 21 13:33:22 UTC 2015

Thank you for your replies.

In most cases the clients are Linux (Fedora 21) and Windows 7 or 8.1. I 
know that this is not exactly an DHCP-Server Problem but I thought that 
this would be the best place to ask.

On my Fedora notebook i have tried to enable both wireless and cable 
connection with dhcpclient and both interfaces getting the same IP. 
After a short time approx. 10 seconds later no communication between my 
notebook and all other devices in my network is possible. So I think 
there is an IP address conflict. Is it possible to configure the clients 
to use a prioritized interface i.e. first cable, second wireless?


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Am 20.02.2015 um 15:19 schrieb Simon Hobson:
> Daniel Thielking<Daniel.Thielking at>  wrote:
>> host laptop-2-lan {
>>    hardware ethernet 18:03:73:7a:61:dd;
>>    fixed-address;
>> }
>> host laptop-2-wireless {
>>    hardware ethernet 38:59:F9:0F:1D:ED;
>>    fixed-address;
>> }
>> behind the DNS-Name ist one ip( configured in bind.
>> Now to the problem:
>> If I use laptop-2 in wireless mode everything works fine. If I want to use a cable both Interfaces are getting the same address. It manifests itself in a ip address conflict. How can I configure DHCPd to avoid this? But I do not want to use more than one address.
> OK, firstly it's not really "a DHCP problem".
> The only way to completely fix it is to ensure that only one interface is active at any time - that's easier said than done. However, I've (in the past) done exactly the same thing and it's worked just fine - client is Apple laptop running OS X. AFAICT OS X doesn't complain if you configure the same IP on two interfaces - it just uses the one that's configured to be higher up the list.
> What is the client in your case ?
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