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My new Ubuntu 11.04 server is having issues with the two Ethernet ports on the motherboard. I only need one port, eth1 so I am trying to disable eth2.

I executed sudo ifconfig eth2 down which only worked temporarily as eth2 repopulated in ifconfig within a short time.

I then modified /etc/network/interfaces to disable it:

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
auto eth1
iface eth1 inet dhcp
#auto eth2
#iface eth2 inet dhcp

and executed sudo /etc/init.d/networking restart and even rebooted the system.

For some reason, after about 10-30 mins, eth2 re-enables itself and interrupts all network traffic on eth1. How can I prevent eth2 from ever enabling itself?

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up vote 0 down vote accepted

It could be because network manager is handling your interfaces. You could try disabling the network-manager service, as its primary benefits are its portability (i'm asssuming your server isn't going to be moving often).

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