#!/bin/sh

# /etc/NetworkManager/dispatcher.d/pre-up.d/randomize-mac-addresses

# Configure every saved WiFi connection in NetworkManager with a spoofed MAC
# address, seeded from the UUID of the connection and the date eg:
# 'c31bbcc4-d6ad-11e7-9a5a-e7e1491a7e20-2017-11-20'

# This makes your MAC impossible(?) to track across WiFi providers, and
# for one provider to track across days.

# For craptive portals that authenticate based on MAC, you might want to
# automate logging in :)

# Note that NetworkManager >= 1.4.1 (Ubuntu 17.04+) can do something similar
# automatically.

export PATH=$PATH:/usr/bin:/bin

LOG_FILE=/var/log/randomize-mac-addresses

echo "$(date): $*" > ${LOG_FILE}

WIFI_UUIDS=$(nmcli --fields type,uuid connection show |grep 802-11-wireless |cut '-d ' -f3)

for UUID in ${WIFI_UUIDS}
do
    UUID_DAILY_HASH=$(echo "${UUID}-$(date +F)" | md5sum)

    RANDOM_MAC="b4:b6:76:$(echo -n ${UUID_DAILY_HASH} | sed 's/^\(..\)\(..\)\(..\).*$/\1:\2:\3/')"

    CMD="nmcli connection modify ${UUID} wifi.cloned-mac-address ${RANDOM_MAC}"

    echo "$CMD" >> ${LOG_FILE}
    $CMD &
done

wait