Tool to read the real MAC address of a Jetson Nano

nano-read-mac.sh

#!/bin/bash
#
# This script reads the correct MAC address of a Jetson Nano from the onboard EEPROM over i2c.
# First install i2c-tools package. Then make this script executable, and run it with sudo:
#
#     $ sudo apt-get install i2c-tools
#     $ chmod +x nano-read-mac.sh
#     $ sudo ./nano-read-mac.sh
#          MAC address is xx:xx:xx:xx:xx:xx
#
# The ‘ip’ command can then change the MAC to above, but it does not persist after rebooting.
#    
#     $ ip link set dev eth0 address xx:xx:xx:xx:xx:xx 
#
# There’s also a “macchanger” package that can be installed, has a text UI, and enables a service to 
# change the MAC persistently (but not permanently).  A patch is being developed for the permanent fix.
#
# For more info, see this forum thread:  https://devtalk.nvidia.com/default/topic/1055188/#5348990
#

if [ `whoami` != root ]; then
	echo "Error -- run this script with sudo:"
	echo "         \"sudo $0\""
	exit 1
fi

mapfile -t mac_lines < <( i2cdump -y -r 172-177 2 0x50 b )

len=${#mac_lines[@]}

if [ "$len" -ne "3" ]; then
		echo "FAILED to read MAC address from i2c..."
		echo "EEPROM content:"
		i2cdump -y 2 0x50 b
else 
	mac_strA=(${mac_lines[1]})
	mac_strB=(${mac_lines[2]})

	echo "MAC address is ${mac_strB[2]}:${mac_strB[1]}:${mac_strA[4]}:${mac_strA[3]}:${mac_strA[2]}:${mac_strA[1]}"
fi