Disappearing network interfaces in Ubuntu Server

If you change network cards on ubuntu server then you will find that the new cards no longer come up. This also occurs when you copy a vmware virtual machine.

To fix this, edit the persistent-net-rules file

sudo vi /etc/udev/rules.d/70-persistent-net.rules

You should see a line (plus a commented heading) for the affected interface(s) like this;

# PCI device 0x14e4:0x1659 (r8169)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:1c:c0:db:32:e7", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

(Forgive the formatting but blogger.com has a ridiculously narrow content column and long lines tend to disappear behind crap on the RHS of the page or wrap around and look like multiple lines)

Anyway, all you need to do is delete the line for the affected interface and reboot your system.

Once the system has rebooted, the persistent-net-rules file will be repopulated with the details for the new interface and your Ethernet adapter will be working once again.