merlin-ovpn-client-watchdog.sh

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

#          name: merlin-ovpn-client-watchdog.sh
#       version: 3.0.1, 05-aug-2022, by eibgrad
#       purpose: restart failed/stopped/unresponsive openvpn clients
#       type(s): services-start
#          href: https://tinyurl.com/2p9a68ne
#  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 wyKu0pww
#    3. modify script w/ your preferred options using nano editor:
#         nano /jffs/scripts/merlin-ovpn-client-watchdog.sh
#    4. reboot

SCRIPTS_DIR='/jffs/scripts'
SCRIPT1="$SCRIPTS_DIR/merlin-ovpn-client-watchdog.sh"
SCRIPT2="$SCRIPTS_DIR/services-start"

mkdir -p $SCRIPTS_DIR

# -------------------- begin merlin-ovpn-client-watchdog --------------------- #
cat << 'EOF' > $SCRIPT1
#!/bin/sh
#set -x # comment/uncomment to disable/enable 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
until 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${i} >/dev/null
        echo "openvpn client #$i (re)started @ $(date)"
    done
done

} 2>&1 | logger -t $(basename $0 .sh)[$$]
EOF
[ ${DEBUG+x} ] && sed -ri '2 s/^#(set -x)/\1/' $SCRIPT1
chmod +x $SCRIPT1
echo "installed: $SCRIPT1"
# --------------------- end merlin-ovpn-client-watchdog ---------------------- #

# --------------------------- begin services-start --------------------------- #
create_script() {
cat << 'EOF' > $SCRIPT2
#!/bin/sh
#set -x # comment/uncomment to disable/enable debug mode
{
nohup $SCRIPT1 &>/dev/null &
} 2>&1 | logger -t $(basename $0)[$$]
EOF
[ ${DEBUG+x} ] && sed -ri '2 s/^#(set -x)/\1/' $SCRIPT2
sed "s:\$SCRIPT1:$SCRIPT1:g" -i $SCRIPT2
chmod +x $SCRIPT2
}

if [ -f $SCRIPT2 ]; then
    echo "error: $SCRIPT2 already exists; requires manual installation"
else
    create_script
    echo "installed: $SCRIPT2"
fi
# ---------------------------- end services-start ---------------------------- #