Some of my OpenWRT routers depend on using a rather unstable wireless connection to reach my OpenVPN server. Although they reconnect very reliably for the most part, sometimes something goes wrong. This is where the watchdog script comes in. It pings the WLAN access point and VPN server every minute. If either one doesn’t respond for a few (configurable) minutes, the watchdog will restart the service. Here’s how it works:
Obsolete!
A new and improved watchping script is available, click here!
Configuration
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config watchping 'wifi' option enabled '1' option host 'wifi.accesspoint' option timeout '3' config watchping 'openvpn' option enabled '1' option host 'my.vpn.server.de' option timeout '5' |
First create a new configuration file /etc/config/watchping. This tells the watchdog which hosts to ping and configures the timeout for each service.
The scripts
Create the /usr/lib/watchping folder and upload these scripts:
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#!/bin/sh # # Pings a remote host and restarts WiFi/OpenVPN if the connection is down # Requires "fping" -> opkg install fping # # Copyright (C) 2020 luani.de . /lib/functions.sh # check prerequisites if [ ! -x "$(command -v fping)" ]; then echo 'watchping error: fping is not installed, exiting' >&2 exit 1 fi # read configuration config_load watchping config_get_bool check_wifi wifi enabled "false" config_get_bool check_openvpn openvpn enabled "false" if [ "$check_wifi" -eq "1" ]; then config_get wifi_host wifi host "localhost" config_get wifi_timeout wifi timeout "5" if [ $wifi_timeout -le 0 ]; then wifi_timeout=5 fi wifi_failcount=0 logger -t "watchping" "start wifi watchdog: host '$wifi_host', timeout $wifi_timeout min" fi if [ "$check_openvpn" -eq "1" ]; then config_get openvpn_host openvpn host "localhost" config_get openvpn_timeout openvpn timeout "5" if [ $openvpn_timeout -le 0 ]; then openvpn_timeout=5 fi openvpn_failcount=0 logger -t "watchping" "start openvpn watchdog: host '$openvpn_host', timeout $openvpn_timeout min" fi # check loop while sleep 60; do if [ "$check_wifi" -eq "1" ]; then fping --ipv4 --quiet --count 1 --random ${wifi_host} &> /dev/null if [ $? -ne 0 ]; then let "wifi_failcount++"; else wifi_failcount=0; fi if [ $wifi_failcount -ge $wifi_timeout ]; then wifi_failcount=0 logger -t "watchping" "wifi ($wifi_host) is down for $wifi_timeout min, restarting!" # restart service # "If wifi is already up when you run "wifi" with no parameters, the wifi system will be stopped and restarted." /sbin/wifi fi fi if [ "$check_openvpn" -eq "1" ]; then fping --ipv4 --quiet --count 1 --random ${openvpn_host} &> /dev/null if [ $? -ne 0 ]; then let "openvpn_failcount++"; else openvpn_failcount=0; fi if [ $openvpn_failcount -ge $openvpn_timeout ]; then openvpn_failcount=0 logger -t "watchping" "openvpn ($openvpn_host) is down for $openvpn_timeout min, restarting!" # restart service /etc/init.d/openvpn restart fi fi done exit 0 |
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#!/bin/sh /etc/rc.common # # start watchdog # # https://openwrt.org/docs/guide-developer/procd-init-script-example # Copyright (C) 2020 luani.de # Init sequence START=99 STOP=10 # PROCD USE_PROCD=1 start_service() { procd_open_instance watchping procd_set_param command /bin/sh "/usr/lib/watchping/watchping.sh" procd_set_param respawn ${respawn_threshold:-3600} ${respawn_timeout:-5} ${respawn_retry:-5} procd_set_param stdout 1 # forward stdout of the command to logd procd_set_param stderr 1 # same for stderr procd_set_param pidfile /var/run/watchping.pid procd_close_instance } stop_service() { logger -t "watchping" "watchdog stopped!" } service_triggers() { procd_add_reload_trigger "watchping" } reload_service() { stop start } |
Final touches
The watchdog script requires „fping“ to be installed on the router:
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# install dependencies opkg update opkg install fping # make executable chmod +x /usr/lib/watchping/watchping.sh chmod +x /etc/init.d/watchping # enable & start service # you can also do this from LuCI, system -> startup /etc/init.d/watchping enable /etc/init.d/watchping start |
Check your system log and verify the watchdog started correctly:
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user.notice watchping: start wifi watchdog: host 'wifi.accesspoint', timeout 3 min user.notice watchping: start openvpn watchdog: host 'my.vpn.server.de', timeout 5 min |
Tested with OpenWRT 19.07
Is it possible to watch an usb device, and reset it with „usbreset“ if it has connection problems?
or maybe the better version:
a custom watchdog provider, where I could check for an Exit code, and if it doesn’t match run an other command
Hi Christian,
have a look at the improved watchdog script: https://luani.de/minis/linux-server/openwrt-improved-network-openvpn-wifi-watchdog/
If your usb device provides a network interface that can be checked by ping, you can specify „usbreset“ as a restart command in the configuration file.
Pingback:OpenWRT: Improved Network/OpenVPN/WiFi watchdog – LUANI
Thanks for your work.
Can you adopt the script to watch out only for the wifi. I don’t need the VPN in my case.
Hi spp, glad you like it. You can disable the VPN watchdog in /etc/config/watchping, just set enabled to „0“.
Thanks a lot.