OpenWrt script to update timezone by IP, should be stored in /etc/hotplug.d/iface/, requires zoneinfo-all

99-timezone

#!/bin/sh

if [ "${INTERFACE}" = "loopback" ]; then
    exit 0
fi
if [ "${ACTION}" != "ifup" ] && [ "${ACTION}" != "ifupdate" ]; then
    exit 0
fi
if [ "${ACTION}" = "ifupdate" ] && [ -z "${IFUPDATE_ADDRESSES}" ] && [ -z "${IFUPDATE_DATA}" ]; then
    exit 0
fi

timezone=$(wget -qO- https://ipinfo.io/timezone)

if [ $? -eq 0 ] && [ -n "${timezone}" ] && [ "${timezone}" != "$(uci get system.@system[0].zonename)" ]; then
    uci set system.@system[0].zonename="${timezone}"
    uci set system.@system[0].timezone="$(tail -n1 /usr/share/zoneinfo/${timezone})"
    uci commit system
    /etc/init.d/system reload
    /etc/init.d/cron restart
fi