tomato-ovpn-client-watchdog.sh

#!/bin/sh
#DEBUG=; set -x # uncomment/comment to enable/disable debug mode

#          name: tomato-ovpn-client-watchdog.sh
#       version: 2.1.0, 08-aug-2022, by eibgrad
#       purpose: (re)start failed/stopped/unresponsive openvpn client(s)
#   script type: wanup (autostart)
#  installation:
#    1. enable jffs (administration->jffs)
#    2. enable 'start with wan' option for openvpn clients to be monitored
#    3. use shell (telnet/ssh) to execute one of the following commands:
#         curl -kLs bit.ly/tomato-installer|tr -d '\r'|sh -s -- MPnU5WrK wanup
#       or
#         wget -qO - bit.ly/tomato-installer|tr -d '\r'|sh -s -- MPnU5WrK wanup
#    4. optional: use vi editor to modify options:
#         vi /jffs/etc/config/tomato-ovpn-client-watchdog.wanup
#    5. reboot
(
# ------------------------------ 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 ----------------------- #

WAN_IF="$(ip route | awk '/^default/{print $NF}')"

# function _ping( client-num )
_ping() {
    [ $PING_MAXTRY -gt 0 ] || return 0

    local i=1
    local conf="/tmp/etc/openvpn/client${1}/config.ovpn"
    local dev="$(grep '^dev[[:space:]]' $conf | tail -1 | awk '{print $2}')"

    # it's best to check multiple times to prevent false negatives
    while :; do
        ping -qc1 -W3 -I $dev $PING_HOST &>/dev/null && return 0
        [ $((i++)) -ge $PING_MAXTRY ] && break || sleep $PING_INTERVAL
    done

    return 1
}

# reject uninitialized wan and additional instances
{ [ "$WAN_IF" ] && mkdir /tmp/$(basename $0 .${0##*.}).lock &>/dev/null; } || exit 0

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

while sleep $INTERVAL; do
    for i in 1 2 3; do
        # only enabled openvpn clients need to be considered
        $(nvram get vpn_client_eas | grep -q $i) || continue

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

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

) 2>&1 | logger -t "$(basename $0 .${0##*.})[$$]" &