Linux: Error, some other host already uses address

The last week I did a migration from a Virtual Machine (VMware based) from ISP A to ISP B, and after starting the machine it worked fine. Then I needed to add a new IP to the eth0 interface so I made an ifcfg-eth0:0 config file with the new IP.

After starting the eth0:0 i got the message:

Error, some other host already uses address

I was sure the IP was free, and I needed the IP attached to an interface so i could get a license for some software i was using.

Then I did some checkup in the ifup-eth file to see if I could bypass the check, and this was possible!

In the script ifup-eth I found a query and did modify this:

/etc/sysconfig/network-scripts/

# if ! /sbin/arping -q -c 2 -w 3 -D -I ${REALDEVICE} ${ipaddr[$idx]} ; then
# net_log $”Error, some other host already uses address ${ipaddr[$idx]}.”
# exit 1
# fi

As you can see we did comment out the check only! So the command works and can bring up the device. Now i finally could retrieve the file and my software started working.

Now i wanted to know what Device is using the IP address. To check this i took the command in the ifup-eth file and modified it:

/sbin/arping -c 2 -w 3 -D -I eth0 123.123.123.123

Replace 123.123.123.123 with your IP address of the device that is not willing to start.

This will show you the MAC address. Now Happy Hunting!

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