merlin-wol-port-forward.sh

#!/bin/sh
#DEBUG= # uncomment/comment to enable/disable debug mode

#          name: merlin-wol-port-forward.sh
#       version: 2.1.0, 27-jul-2022, by eibgrad
#       purpose: wol to target of port forwarding
#       type(s): init-start, nat-start
#          href: https://tinyurl.com/2hwea3y7
#  installation:
#    1. enable jffs custom scripts and configs (administration->system)
#    2. ssh to router and copy/paste the following command:
#         curl -kLs bit.ly/merlin-installer|tr -d '\r'|sh -s b7p6f102
#    3. modify script w/ your preferred options using nano editor:
#         nano /jffs/configs/merlin-wol-port-forward.options
#    4. reboot

CONFIGS_DIR='/jffs/configs'
CONFIG="$CONFIGS_DIR/merlin-wol-port-forward.options"

SCRIPTS_DIR='/jffs/scripts'
SCRIPT1="$SCRIPTS_DIR/merlin-wol-port-forward.nat"
SCRIPT2="$SCRIPTS_DIR/merlin-wol-port-forward.init"
SCRIPT3="$SCRIPTS_DIR/nat-start"
SCRIPT4="$SCRIPTS_DIR/init-start"

mkdir -p $CONFIGS_DIR $SCRIPTS_DIR

# ------------------ begin merlin-wol-port-forward.options ------------------- #
cat << 'EOF' > $CONFIG
# ------------------------------ BEGIN OPTIONS ------------------------------- #

# protocol (tcp|udp) of port forward
PROTO='tcp'

# source ip(s)/network(s) of port forward (comma-separated)
SOURCE='0.0.0.0/0'

# external port of port forward
EXT_PORT='5900'

# internal ip of port forward
INT_IP='192.168.1.100'

# internal port of port forward
INT_PORT='5900'

# mac address of internal ip (unspecified = static lease search)
MAC_ADDR='' # hexidecimal format: XX:XX:XX:XX:XX:XX

# broadcast interface of internal ip
BCAST_IF='br0'

# how often (in secs) to check for new wol messages
INTERVAL=10

# ------------------------------- END OPTIONS -------------------------------- #
EOF
echo "installed: $CONFIG"
# ------------------- end merlin-wol-port-forward.options -------------------- #

# -------------------- begin merlin-wol-port-forward.nat --------------------- #
cat << 'EOF' > $SCRIPT1
#!/bin/sh
#set -x # comment/uncomment to disable/enable debug mode
{
. $CONFIG

# create port forward
iptables -t nat -I VSERVER -p $PROTO -s $SOURCE --dport $EXT_PORT \
    -j DNAT --to $INT_IP:$INT_PORT

# record access of port forward to log
iptables -t nat -I VSERVER -p $PROTO -s $SOURCE --dport $EXT_PORT \
    -j LOG --log-prefix "WPF: DIP=$INT_IP "

exit 0
} 2>&1 | logger -t $(basename $0)[$$]
EOF
[ ${DEBUG+x} ] && sed -ri '2 s/^#(set -x)/\1/' $SCRIPT1
sed -i "s:\$CONFIG:$CONFIG:g" $SCRIPT1
chmod +x $SCRIPT1
echo "installed: $SCRIPT1"
# --------------------- end merlin-wol-port-forward.nat ---------------------- #

# -------------------- begin merlin-wol-port-forward.init -------------------- #
cat << 'EOF' > $SCRIPT2
#!/bin/sh
#set -x # comment/uncomment to disable/enable debug mode
(
. $CONFIG

# mask used for finding wol messages
WOL_MSG_MASK="[W]PF: DIP=$INT_IP .* PROTO=$PROTO .* DPT=$INT_PORT "

# work files
CURR_MSG="/tmp/tmp.$$.curr_msg"
PREV_MSG="/tmp/tmp.$$.prev_msg"; > $PREV_MSG

# ignore any saved wol messages across a reboot
if [ -f /jffs/syslog.log ]; then
    grep "$WOL_MSG_MASK" /jffs/syslog.log > $PREV_MSG
fi

# wait for *reliable* internet connection
until ping -qc1 -W3 8.8.8.8 &>/dev/null; do sleep 10; done

# validate mac address
if [ ! "$MAC_ADDR" ]; then
    MAC_ADDR=$(get_mac $INT_IP)
    if [ ! "$MAC_ADDR" ]; then
        echo "fatal error: mac address not found: $INT_IP"
        exit 1
    fi
else
    if ! echo "$MAC_ADDR" | \
            grep -qE '^([[:xdigit:]]{2}:){5}[[:xdigit:]]{2}$'; then
        echo "fatal error: invalid/malformed mac address: $MAC_ADDR"
        exit 1
    fi
fi

while sleep $INTERVAL; do
    # extract all wol messages
    grep "$WOL_MSG_MASK" /tmp/syslog.log > $CURR_MSG

    # if there are any new wol messages, then wol as necessary
    if [ -s $CURR_MSG ] && ! ping -qc1 -W3 $INT_IP &>/dev/null; then
        if [ ! -s $PREV_MSG ] || \
                grep -m1 -Fxvf $PREV_MSG $CURR_MSG >/dev/null; then

            # try up to three (3) times to wake the device
            for i in 1 2 3; do
                echo "info: waking up $MAC_ADDR (attempt #${i}) ..."
                ether-wake -bi $BCAST_IF $MAC_ADDR && sleep 20 || break
                if ping -qc1 -W3 $INT_IP &>/dev/null; then
                    echo "info: $MAC_ADDR is alive!"
                    break
                fi
                [ $i -eq 3 ] && echo "warning: $MAC_ADDR did NOT respond :("
            done
        fi
    fi

    # remember which wol messages have already been processed
    mv $CURR_MSG $PREV_MSG
done
) 2>&1 | logger -t $(basename $0)[$$] &
EOF
[ ${DEBUG+x} ] && sed -ri '2 s/^#(set -x)/\1/' $SCRIPT2
sed -i "s:\$CONFIG:$CONFIG:g" $SCRIPT2
chmod +x $SCRIPT2
echo "installed: $SCRIPT2"
# --------------------- end merlin-wol-port-forward.init --------------------- #

# ----------------------------- begin nat-start ------------------------------ #
create_script() {
cat << 'EOF' > $SCRIPT3
#!/bin/sh
#set -x # comment/uncomment to disable/enable debug mode
{
$SCRIPT1
} 2>&1 | logger -t $(basename $0)[$$]
EOF
[ ${DEBUG+x} ] && sed -ri '2 s/^#(set -x)/\1/' $SCRIPT3
sed -i "s:\$SCRIPT1:$SCRIPT1:g" $SCRIPT3
chmod +x $SCRIPT3
}

if [ -f $SCRIPT3 ]; then
    echo "error: $SCRIPT3 already exists; requires manual installation"
else
    create_script
    echo "installed: $SCRIPT3"
fi
# ------------------------------ end nat-start ------------------------------- #

# ----------------------------- begin init-start ----------------------------- #
create_script() {
cat << 'EOF' > $SCRIPT4
#!/bin/sh
#set -x # comment/uncomment to disable/enable debug mode
{
$SCRIPT2
} 2>&1 | logger -t $(basename $0)[$$]
EOF
[ ${DEBUG+x} ] && sed -ri '2 s/^#(set -x)/\1/' $SCRIPT4
sed -i "s:\$SCRIPT2:$SCRIPT2:g" $SCRIPT4
chmod +x $SCRIPT4
}

if [ -f $SCRIPT4 ]; then
    echo "error: $SCRIPT4 already exists; requires manual installation"
else
    create_script
    echo "installed: $SCRIPT4"
fi
# ------------------------------ end init-start ------------------------------ #