Tag: VirtualBox
[VirtualBox/Linux/Windows] Copied Linux Guests Increasing eth devices
by Chuck Kozler on Jan.13, 2010, under Computers, Linux/Unix, Ubuntu, Windows
I noticed that when you copy Linux guests (VBoxManage clonevdi) and then try to use them, your ethernet device adapters keep increasing by one (eth0,eth1,eth2..etc).
This happens because the OS is looking in /etc/udev/rules.d/70-persistent-net.rules to look for the MAC address and corresponding adapter. Since the MAC address on the now new guest has been changed by VirtualBox, obviously the Guest OS can not find this MAC address. Naturally, it disables eth0 and creates eth1 with the new VirtualBox generated MAC address.
This can become quite troublesome, especially if you make a copy of a copy of a copy and so on.
I wrote a quick script to swap these MAC addresses around for you. I had to write something like this because I had to deploy about 20 Virtualized Guests and I created a base VDI to copy over and over as I needed it. I placed this script in the /root directory so I could just “su” and execute it, restart, and my address was fixed.
#!/bin/bash user=`whoami` if [ $user != "root" ]; then echo "You must be root to run this. Exiting." exit 300 fi function swapMacs { eth0_mac=`cat /etc/udev/rules.d/70-persistent-net.rules | grep -i "eth0" | cut -d ',' -f4 | cut -d '=' -f3 | cut -d '"' -f2 | sed -e 's/:/\\\\:/g'` if [ -z $eth0_mac ]; then echo " ! MAC Address for eth0 is empty. Could not retrieve MAC from udev file." exit 100 fi eth1_mac=`cat /etc/udev/rules.d/70-persistent-net.rules | grep -i "eth1" | cut -d ',' -f4 | cut -d '=' -f3 | cut -d '"' -f2 | sed -e 's/:/\\\\:/g'` if [ -z $eth1_mac ]; then echo " ! MAC Address for eth1 is empty. Could not retrieve MAC from udev file. ( Are you sure the line exists? )" exit 100 fi echo " * Find old mac: $eth0_mac" echo " * Replacing with: $eth1_mac" sed -i "s/$eth0_mac/$eth1_mac/g" /etc/udev/rules.d/70-persistent-net.rules if [ $? -eq 0 ]; then echo " + Successfully swapped mac addresses" echo " * Setting new udev file" new_rule=`cat /etc/udev/rules.d/70-persistent-net.rules | grep -i "eth0"` echo $new_rule > /etc/udev/rules.d/70-persistent-net.rules if [ $? -eq 0 ]; then echo " + We have successfully updated the udev file" else echo " ! Problem updating the udev file" exit 100 fi else echo " ! Problem swapping mac addresses" exit 100 fi } swapMacs
