I have a urgent problem to solve today, but I'm lost. Please help. I've cloned a Virtual Machine hosted on VM Ware ESXi 4.1 The OS is now Ubuntu Server 12.04 LTS, but at the time of cloning it was 10.04 LTS. I fixed the MAC address manually inside /etc/udev/rules.d/70-persistent-net.rules. It is a known problem on Ubuntu. I had to remove the old MAC address and set the new one as eth0. Everything seems to work fine, except ARP. My provider OVH sent me a warning to resolve it today (this is the second day) or they will block my IP! The log contains many lines like this: Tue Jun 5 01:04:29 2012 : arp who-has 178.32.136.212 tell 178.32.136.224 where .224 is the cloned server that is causing problems, and .212 is the cloned one. arp -na returns: ? (178.33.230.254) at 00:07:b4:00:00:02 [ether] on eth0 ? (178.32.136.212) at 00:50:56:09:8e:f1 [ether] on eth0 The first IP is the ESXi machine. The second one should not be there. I'm not an expert and I don't know what else to do to fix this problem. Any help will be very appreciated. Thanks. EDIT: ifcofig on .224: eth0 Link encap:Ethernet HWaddr 00:50:56:01:32:c6 inet addr:178.32.136.224 Bcast:178.32.136.255 Mask:255.255.255.0 inet6 addr: fe80::250:56ff:fe01:32c6/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:399924 errors:0 dropped:465 overruns:0 frame:0 TX packets:241884 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:58006071 (58.0 MB) TX bytes:663603166 (663.6 MB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:516216 errors:0 dropped:0 overruns:0 frame:0 TX packets:516216 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:236284275 (236.2 MB) TX bytes:236284275 (236.2 MB) ifconfig on .212: eth0 Link encap:Ethernet HWaddr 00:50:56:09:8e:f1 inet addr:178.32.136.212 Bcast:178.32.136.255 Mask:255.255.255.0 inet6 addr: fe80::250:56ff:fe09:8ef1/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:16014 errors:0 dropped:0 overruns:0 frame:0 TX packets:14511 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:15134444 (15.1 MB) TX bytes:2683025 (2.6 MB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:9944 errors:0 dropped:0 overruns:0 frame:0 TX packets:9944 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1139347 (1.1 MB) TX bytes:1139347 (1.1 MB)