merlin-ovpn-watchdog-74660.sh

#!/bin/sh
# version: 2.1.0, 03-dec-2021, by eibgrad
# href: https://tinyurl.com/2p9a68ne

SCRIPTS_DIR='/jffs/scripts'
SCRIPT="$SCRIPTS_DIR/services-start"

mkdir -p $SCRIPTS_DIR

create_script() {
cat << "EOF" > $SCRIPT
#!/bin/sh
set -x # uncomment/comment to enable/disable debug mode
(
# ------------------------------ BEGIN OPTIONS ------------------------------- #

# time (in secs) between checks for failed/stopped/unresponsive openvpn clients
INTERVAL=60

# internet host used for ping checks
PING_HOST='8.8.8.8'

# time (in secs) between ping checks
PING_INTERVAL=10

# maxmium number of ping checks before being considered a failure
PING_MAXTRY=3 # (3 recommended, 0 disables ping checks)

# ------------------------------- END OPTIONS -------------------------------- #

# ---------------------- DO NOT CHANGE BELOW THIS LINE ----------------------- #

# function _ping( vpn-network-interface )
_ping() {
    [ $PING_MAXTRY -gt 0 ] || return 0

    local i=1

    # it's best to check multiple times to prevent false negatives
    while :; do
        ping -qc1 -w3 -I $1 $PING_HOST &>/dev/null && return 0
        [ $(( i++ )) -ge $PING_MAXTRY ] && break || sleep $PING_INTERVAL
    done

    return 1
}

# wait for *reliable* internet connection
while ! ping -qc1 -w3 $PING_HOST &>/dev/null; do sleep 10; done

while sleep $INTERVAL; do
    for i in 1 2 3 4 5; do
        # only enabled openvpn clients need to be considered
        [ "$(nvram get vpn_client${i}_state)" != '0' ] || continue

        # check for failed connection or unresponsive tunnel
        pidof vpnclient${i} &>/dev/null && _ping tun1${i} && continue

        # fall-through means failure; restart the openvpn client
        service restart_vpnclient${i}
        echo "openvpn client #$i (re)started @ $(date)"
    done
done

) 2>&1 | logger -t $(basename $0)[$$] &
EOF
chmod +x $SCRIPT
}

if [ -f $SCRIPT ]; then
    echo "error: $SCRIPT already exists; requires manual installation"
else
    create_script
    echo "installed: $SCRIPT"
fi