Modifications made with the ethtool command are by default disappeared after a reboot. For permanent settings, the interface configuration file has to be edited. For each network device, there will be a file in the /etc/sysconfig/network-scripts/
For example, for device eth0 there will be /etc/sysconfig/network-scripts/ifcfg-eth0 containing the properties of the device. A line can be added to the file to automatically implement the settings allowed by the “ethtool -s” command. For example:
# vi /etc/sysconfig/network-scripts/ifcfg-eth0 ETHTOOL_OPTS="autoneg off duplex full speed 100"
Refer to “man ethtools” for options allowed with the “-s” switch.
# man ethtool
These are the only switch options that can be implemented this way because the “ifup” script is not coded to handle other options.
Restart the network service for the changes to take effect:
# service network restart
If this is not the primary interface in use and you have logged in with another IP that is not plumbed to this interface, you can also use “ifdown” and “ifup” commands to make the ethtool settings active.
# ifdown eth0 ifup eth0
These settings will be set permanently, so even after a reboot of the servers you should see these settings intact.