openWRT automatic Wake on LAN

README.md

To make iptables work, make sure that you have netfilter installed:

opkg install kmod-br-netfilter

Thanks, @Reutertu3

autowol.sh

#!/bin/sh
# Inspired by https://wiki.openwrt.org/doc/howto/auto_wake_on_lan
# - code that does not hurt my eyes
# - log that does eat up all the memory
set -euo pipefail
#set -x

target=192.168.0.1
mac=01:23:45:67:89:ab
interface=br-lan

interval=2
t_wait_for_boot=5
logfile="/www/wol/index.html"
max_log_lines=200

echo "<meta http-equiv="refresh" content="5">" > $logfile
echo "AUTO WOL started at $(date +%F__%H-%M-%S)<br>" >> $logfile

log() {
    #echo $@
    echo "$@<br/>" >> $logfile
}
rotate_log() {
    count=$(wc -l $logfile | awk '{ print $1 }')
    if [ $count -gt $max_log_lines ]; then
        head -2 $logfile > /tmp/autowol.log.tmp
        tail -50 $logfile >> /tmp/autowol.log.tmp
        mv /tmp/autowol.log.tmp $logfile
    fi
}

old=""
while sleep $interval; do
    rotate_log
    last_line=$(logread | grep "WOL_LOG.*DST=$target" | tail -1)
    if [ "$last_line" != "" -a "$last_line" != "$old" ]; then
        dt=$(date "+%F %H:%M:%S")
        src=$(echo $last_line | sed -Ee 's/.* SRC=([0-9.]+) .*/\1/')
        if ping -q -W 1 -c 1 $target >/dev/null; then
            log "$dt NOWAKE SRC=$src DST=$target"
        else
            log "$dt WAKE SRC=$src DST=$target"
            etherwake -i $interface $mac >> $logfile
            log ""
            sleep $t_wait_for_boot
        fi
        old=$last_line
    fi
done

etc_firewall.user

iptables -I FORWARD 1 -p tcp -d 192.168.0.1 -m limit --limit 1/min -j LOG --log-prefix "WOL_LOG:  " --log-level 7

etc_init.d_autowol

#!/bin/sh /etc/rc.common

START=90
STOP=90
 
PIDFILE=/var/run/autowol.pid

start() {        
        /root/autowol.sh &
        echo $! > $PIDFILE
}                 
 
stop() {          
        kill -15 `cat $PIDFILE`
        rm $PIDFILE
}

etc_sysctl.conf

# run bridged traffic through iptables too
# http://superuser.com/a/928246
net.bridge.bridge-nf-call-iptables=1

# and update with
# sysctl -p

LICENSE.txt

The MIT License (MIT)

Copyright (c) 2015 Felix Hummel

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Would you mind if I turned this into an OpenWRT package for community use?

@legostax Yes, of course, please do. :)

Thank you for this amazing script. Bridge firewall doesn't come per default and needs to be installed before the iptables entry works. Could maybe include this in the comment.

opkg install kmod-br-netfilter

Thanks, @Reutertu3!
I put it in the README. :)

Hi, will it still work since OpenWRT moved away from iptables to nftable?

Hi, will it still work since OpenWRT moved away from iptables to nftable?

On 22.03.2 I was able to do it via editing file /etc/nftables.d/10-custom-filter-chains.nft. Uncomment and edit:

 chain user_post_forward {
     type filter hook forward priority 1; policy accept;
     ip daddr <nas-ip> ct state new log prefix "WOL_LOG: "
 }

Afterward, I do see log entries with such prefix when I hit my nas.

logread -f -e WOL_LOG