how to use ifplugd in Linux to execute a command or script when a NIC cable is unplugged or plugged in
It is fairly simple to use once you know how to use it. However, the tricky thing is that by default it doesn't seem to be active or listen on any interface on manually specified.
How To Install ifplugd
First we install ifplugd
sudo apt install ifplugd
Let's enable it on our desired device(s)
vi /etc/default/ifplugd
set this line as so:........
Local Vs Universally Administered MAC Address NIC Refuses to come up
2,6,A or E is what the second digit of your MAC address must be otherwise a lot of OS's will not work. They will say the NIC is down/not connected even though it is.
This is because if the second digit is not set properly it will not view as a valid MAC or device uplink. This is especially an issue with VMs whether in QEMU etc.. if you are making your own MAC.
MAC address is invalid
c4:d1:aa:e5:10:05
To fix it just........
HP Procurve Switch 2824 CLI Telnet Experience , Guide and Tutorial
telnet 192.168.1.54
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ProCurve J4903A Switch 2824
Software revision I.10.77
Copyright (C) 1991-2009 Hewlett-Packard Co. All Rights Reserved.
RESTRICTED RIGHTS LEGEND
Use, duplication, or disclosure by the Government is subject........