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Server Monitoring with Old Cellphone - Beginings of an Idea


#1

I have the beginings of a weekend project idea but I just need to wrap it up with a bow. What I want to do is use an old cell phone to monitor the servers in my rack and remotly turn on servers.

There are already free apps out there that you can throw on an old cell that will monitor servers on LAN and send out notification in even of down server. But I was thinking the other day when my PFSense box went down for reasons unknow, I would like to be able to turn my PFSense box back on remotly. Any other system on my network can be turned on remotly by VPNing home and using wake on lan but if the PFSense box goes down I am out of luck.

I have an old cellphone and a spare Google FI data only SIM. Any Ideas on how I can turn on my firewall remotly?


#2

I don’t know any good way to interface with a stock phone beside using some hackery. Just to get this out of the way: There is a GSM Shield for the arduino platform and also clones with only the sim card part where you could do something like that quite easily. The downside is, that the shield costs money.

Not sure how far you want to go down the DIY Mac Gyver route but here you go:

I am not sure if you can use the USB port somehow but that might be an option. :thinking:
The easiest thing that I can think of is to use the small LED lamp in most phones and wire a driver + relay into that. An app can toggle the LED when connection to the PFsense box is lost which in turn toggles the relay that is wired between the power supply of the PFsense box.


#3

I don’t think I want to go that deep.

Here is an idea I think could be made to work. But I need to start looking into wake on lan to figure out it’s limitations. I have a spare rasberry pie. I could have the Rasberry Pi connected to the pfsense box directly to a spare ethernet port that has wake on lan enabled. I could have the old cellphone connected to the usb port on the pi. It might be possible to write a small app for the pi and the phone that would allow the phone to tell the pi to send a wake on lan packet to the pfsense box.

Does that sound plausable?


#4

It sure does!

I am just not certain how to go about making it work with USB myself, therefore my vague sentence regarding USB. Personally I am very comfortable with soldering that’s why my suggestion was leaning in that direction. You know, got a hammer, so the problem looks like a nail :wink:.

btw, if you directly reply to my post I get notified, otherwise not. There are a lot of threads and nobody checks all the threads all the time. :slightly_smiling_face:


#5

Just going to throw this out there. You can send Wake on Lan “Magic Packets” to whatever system you want from your monitoring system with a command. After a quick Google search linux has either etherwake or wakeonlan tools that can do this.

If you go the raspberry pi route it should be pretty easy. Just have to integrate that command into a script or interface somehow. Looks like you just need to know the MAC of the system you’re trying to wake.


#6

Does it need to be with a phone?
You can monitor servers/network equipment with prtg
with some minor configuring you can setup a .exe to do wake on lan and call it from prtg aswell.
It supports mail,sms and push notifications with an app.
The tool is free for the first 100 things u monitor. for example ping to 192.168.1.1 is 1 ‘sensor’
SNMP from a switch could be a different sensor, a dns check etc etc.
100 is usually plenty for home use

The only downside is that it has to run on a windows machine as far as I know.
I’m running it on a server with several VM’s thats always on.
If you don’t mind having a windows machine on 24/7 this could be a clean solution with lots of feature’s/expandability


#7

I did this with a ryzen build that had, not yet diagnosed, motherboard issues that would cause the computer to just drop off the network and it would not reappear until you physically reset the computer. But if the computer disappears from the network, you can’t ssh into to reset. So I put a raspberry pi in the case, attached an electronic relay to the pi’s gpio pins, and attached the motherboard’s reset pins to the relay. If the pi could not ping the ryzen computer, it just toggled the reset circuit.

Ryzen host with pi and relay attached to host's reset pins (large picture)

I used the wiring pi library which has a simple C interface. It would be trivial to put nginx on the pi and call the wiring pi library though a cgi program. That’s what I do with my garage too.