rename eth1 to eth0

if you change motherboard and restart ubuntu system,
you may find all networks can't work with correct interfaces.
You can rename the interface to map the correct networks.

1.modify the /etc/udev/rules/70-persistent-net.rules
#vim /etc/udev/rules/70-persistent-net.rules

change eth? to correct number with mac address

2.remove all setting on /etc/network/interfaces except lo setting
vim /etc/network/interfaces

3.reboot server

4.add network setting on /etc/network/interfaces
vim /etc/network/interfaces
auto eth1
iface eth1 inet static
address 10.x.x.x
network 255.255.255.x
gateway 10.x.x.x.x

5.restart networks
#/etc/init.d/networking restart