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Knowledge Check Question 3.1


Why is IP the only correct answer when in the Layer 2: Configuration section they use ifconfig, ip and ethtool to alter L2 configuration of an adapter?


  • RonaldBarnes
    RonaldBarnes Posts: 14
    edited December 2020

    This is still an issue in December 2020.

    Examples are given under "Layer 2 configuration" using ifconfig & ip to set MTU and ethtool to set link speed, yet only ip is considered a correct answer.

    Layer 2: Configuration

    The following commands are used to change the maximum transmission unit (MTU):

    # ifconfig eth0 mtu 1492
    # ip link set mtu 1492 dev eth0

    The following command is used to change the link speed:
    # ethtool -s eth0 speed 1000 duplex full

  • eg15
    eg15 Posts: 1

    This is still an issue in the end of 2020.

    You can also change an interface MAC address with both ifconfig and ethtool and this is obviously a Layer 2 operation.

    It's really straightforward with ipconfig like

    # ifconfig eth0 hw ether xx:xx:xx:xx:xx:xx

    It's more tricky with ethtool because you'll have to mangle with EEPROM but it's still feasible.
    Google just found me a good write-up about it here: https://blog.kanbach.org/post/how-to-permanently-change-a-mac-address-using-ethtool/

  • lee42x
    lee42x Posts: 380

    Hello, eg15,RonaldBarnes and timothyaw,

    Two items today:
    First, all occurrences of the "ifconfig" command have been eradicated from the material.
    The second part is the question 3.1, it has also been removed.

    Without starting a flame war, ifconfig is dead, let me quote the man page:
    This program is obsolete! For replacement check ip addr and ip link. For statistics use ip -s link.:

    The question was removed because "can" do something vs "should" do something made it a poor question. The number of methods to change the IP addresses, MAC addresses and ip parameters is actually quite a long list and declaring one method to be "best" is problematic.

    Regards, Lee


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