Christos Georgiadis

Problem Description

I encountered numerous times network issues where I had to manually intervene and resolve them. When the root cause is always the same, you may want to automate the resolution. Beware though, don’t try to automate something that does not occur frequently enough, otherwise you spent time and effort for trivial things that don’t bring any value. When I try to automate something, it is because I am fed up doing it manually (so it is proven it can be automated) or if I want to learn something new.

In this particular case, I have VPN connections to several remote locations and one of them sits behind CGNAT and a 4G router. If, for whatever reason, I lose the VPN to that remote site, I cannot initialize the VPN connection from the central site since the remote site is ‘hidden’ behind the provider’s NAT. In other words, I don’t know its public IP address. After a few trips to the site, I realize the interface (the wlan and eth0) go down and lose their IP address. Up until know, I don’t know the reason, I suspect it has something to do with the DHCPCD service and I am planning to replace it with networkmanager service in the near future. But for now, I need to automate the network recovery. This is all in a raspberry pi running the latest raspberry OS.

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In a previous article I explained how to install telegraf on OPNSense so that you can collect several metrics from the box into your influxdb. In my case, since OPNSense is my DHCP, DNS and VPN server I really want to know if something happened to it and when.

Since I could not really use telegraf to monitor my wireguard connections because of this, I focused on getting metrics from the wireguard interfaces themselves. If the VPN was down there would be no traffic on those interfaces. In order to collect network metrics, you need to go to OPNSense –> Services –> Telegraf –> Input and check the Network checkbox as this is not enabled by default. Once you do that you see the following in influxdb

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Why monitor OPNSense

For those not familiar with OPNSense, is an opensource firewall and routing platform. I use it mainly for DHCP, DNS server, port forwarding, dynamic DNS and VPN server (viva wireguard!). Since many things depend on it, I really wanted to have a way to monitor it. Now you will tell me, what’s the point of monitoring since you will not be even notified if OPNSense goes down. I will not have internet so any notification outside my LAN will be impossible. it could be though that through monitoring, I can at least see into historical data and find out what might have gone wrong.

Monitoring Solution

I have already setup with different docker containers, influxdb and grafana to monitor my openHAB server so everything is almost setup. Influxdb is a time series database that stores data from vaious sources and grafana pulls those data and create very nice-looking graphs. At this point, I am still working in adding several data sources and metric to monitor so I am not too focused on making everything look nice. That will come later.

How to push data to InfluxDB

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It’s the first time I live in a house that has thermostats (one per floor) to control the heating. They are not ‘smart’ thermostats, but over the years and after fiddling with many useless ‘smart’ devices, you tend to appreciate the simplicity of a good old ‘dump’ device. Now that it’s winter and I started using them I realized I don’t like them very much.

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opeenHAB being a vendor and technology agnostic smarthome software provides the posibility to use HTTP to do the following among other things

• Import values from external devices
• Pull data from openhab API
• Update modify and delete values using HTTP POST / DELETE / PUT

You can do this with

• HTTP Actions or
• HTTP binding

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