ref: https://github.com/lathiat/avahi/blob/master/avahi-autoipd/main.c

link_local_ipv4.sh

#!/bin/bash

set -e

if [ -z "$1" ]; then
	echo "Usage: $0 <iface>"
	exit 1
fi

mac=$(cat /sys/class/net/$1/address)
mac1=$(echo $mac | awk -F ':' '{print "0x"$1}')
mac2=$(echo $mac | awk -F ':' '{print "0x"$2}')
mac3=$(echo $mac | awk -F ':' '{print "0x"$3}')
mac4=$(echo $mac | awk -F ':' '{print "0x"$4}')
mac5=$(echo $mac | awk -F ':' '{print "0x"$5}')
mac6=$(echo $mac | awk -F ':' '{print "0x"$6}')

sum=0
sum=$(($sum + ($mac1 * 1)))
sum=$(($sum + ($mac2 * 2)))
sum=$(($sum + ($mac3 * 3)))
sum=$(($sum + ($mac4 * 4)))
sum=$(($sum + ($mac5 * 5)))
sum=$(($sum + ($mac6 * 6)))

sum=$((($sum % 0xFE00) + 0x0100))
IPV4LL_NETWORK=$((0xA9FE0000))
ip=$(($IPV4LL_NETWORK | $sum))

ip1=$(($ip >> 24))
ip2=$((($ip & 0xff0000) >> 16))
ip3=$((($ip & 0xff00) >> 8))
ip4=$(($ip & 0xff))

printf "%d.%d.%d.%d" $ip1 $ip2 $ip3 $ip4