Change active ethernet port

If you have 2 ethernet ports and you want to switch to make the other one active you can do it with this procedure.  To make eth0 inactive and eth1 active do the following:

nano /etc/sysconfig/network-scripts/ifcfg-eth0
change the “onboot=yes” to “onboot=no”
Also note the IP settings which you are likely to want to copy over to the other port.

nano /etc/sysconfig/network-scripts/ifcfg-eth1
change the “onboot=no” to “onboot=yes”      

Also change any of the IP settings to whatever you want which I won't bother explaining.        

reboot or startup by typing the following commands:
eth0 down
eth1 up