Network connection watcher script

netwatch.sh

#!/bin/bash
set -u -e
exec >> /tmp/conncheck.log
exec 2>&1

router_ip="192.168.20.1"
ping_ip="8.8.8.8"
admin_pw="$(echo '.....insert base64 encoded pw here .....'|base64 -d)"
check_interval=300
recheck_count=10
recheck_interval=40
router_recheck_interval=5

check_net () {
    ping -c 1 "$ping_ip"
}

check_router () {
    ping -c 1 "$router_ip"
}

reboot_router () {
    time (sleep 10; echo -e 'admin'; sleep 3; echo "$admin_pw"; sleep 5; echo 'system reboot') |
        nc -q 10 "$router_ip" 23
}

while true; do
    echo "*** conn check @ $(date)"

    if ! check_net; then
        ok=
        echo "*** suspected connection failure"
        for ((i = 0; i < 3; i++)); do
            if check_net; then
                ok=y
                break
            fi
        done
        if [ -z "$ok" ]; then
            router_ok=y
            while ! check_router; do
                echo "*** cannot contact the router"
                sleep $router_recheck_interval
                router_ok=
            done
            if [ -z "$router_ok" ]; then
                # perhaps the router was down, let it reboot
                sleep $recheck_interval
            fi
            if [ -n "$router_ok" ] || ! check_net; then
                echo "*** rebooting the router"
                reboot_router
                ok=
                for ((i = 0; i < recheck_interval; i++)); do
                    echo "*** waiting for network connection"
                    sleep $recheck_interval
                    if check_net; then
                        echo "*** success"
                        ok=y
                        break
                    fi
                done
                if [ -n "$ok" ]; then
                    continue
                fi
            fi
        fi
    fi

    sleep $check_interval
done