Ping plugin used with computer name

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Hi guys,

having a little problem with the ping plugin. I use it to test two pc’s for presence. But only one of them has a fixed ip, so I use the name as host for this device. Works fine when this pc is on, but when off I get an error: getaddrinfo ENOTFOUND. Can you somehow help?

regards,
Anduril

@Anduril said:

a little problem with the ping plugin. I use it to test two pc’s for presence. But only one of them has a fixed ip,

What kind of Router do you use? I assume the name resolution applies to a host on the local network and you router should provide the name resolution. In a typical home home network setting the DSL Router provides a local DNS server for the host on the network, e.g. Fritzbox provides this out-of-the-box and I can ping my “firefly” host as “firefly.fritz.box”. Note, however, the local DNS may remove local entries after some time.

I’m using a speedport w724v, a special router of our provider (Deutsche Telekom). It has quite often the problem of mixing the names and ip’s, so I use fixed ip’s where possible. But this one is mobile and I don’t want to change between automatic and fixed ip all the time. is it possible to deactivate the error message?

@Anduril said:

is it possible to deactivate the error message?

Unfortunately no., but this could be implemented. For example, as part of pimatic-probe I have implemented a strategy to log repeatedly occurring errors only once. Another strategy is to suppress all error messages, e.g., by introducing a “silent” mode. Note beyond I think it is unwise to change the log level of the specific log message as this may problematic in other case where the ENOENT is an error, e.g. due to a bad configuration

@Anduril do you have the possibility to reserve DHCP leases in your router? If yes then all you need to do is assign an IP to the mobile computer it will pick up the same IP each time you connect to your network.

@sebastienvg Most likely this is not supported. Fritzbox does not support this at least via Web UI. It is possible via command-line though.

Well this should be possible with a speedport.
Konfiguration/Netzwerk -> “Nat & Portregeln” -> “Liste für zugelassene Geräte” / “Weiteres Gerät hinzugefügen”.

Normally this needs to be done to define portrules but has the side-effect that the speedport will assign this device the same ip each time.

@Oitzu said:

… the side-effect that the speedport will assign this device the same ip each time.

Interesting. Thanks for pointing this out.

@Oitzu thanks for your hint, but there is no menu as you described. Maybe the W724V has a different GUI than yours. I can also send you a screenshot, but don’t know how to add it to this post.
I know where to setup the lease time for the dhcp, but this was reduced. I had problems connecting to the wifi and called a technician, who statet that it’s known to have kind of overflow in its name cache for dhcp… crap firmware…
I use port forwarding with at my fixed ip’s, and even they get messed up sometimes by this router. Also when rebooting, it deletes it’s complete dhcp cache, so all devices with dhcp get new adresses.

If the problem is know, isn’t there a possibility to get other working hard- or firmware ?

I think the best solution is, to ping the mac adress. Perhaps the autor can add this feature.

@noxx said:

think the best solution is, to ping the mac adress. Perhaps the autor can add this feature.

As far as I know the underlying net-ping package does not support this (it does ICMP only). One would need to integrate an ARP-cache abstraction such as as node-ife or an implementation of the ARP protocol, e.g. arpjs.

@mwittig agreed, additionally if your home network is connected by VPN with work network, then pinging Mac address would be useless because I could be at work and pimatic would think I am home.

@sebastienvg
Depends on how the router handles VPN connections. Sometimes the MAC address gets lost, also hostnames can get lost in a VPN scenario.
IP is the most likely one to find it’s way to ping’s approach. Even then the VPN settings affect (Assigned local network ip by the VPN).

I would take a second look at the DHCP reservation lists. It’s highly unlikely it would not be in the settings of the router, even with custom firmwares of your operator.

https://telekomhilft.telekom.de/riokc95758/attachments/riokc95758/Fragen/309528/1/Screenshot+2014-02-13+21.45.40.png This came up with Google, I’m not fluent with German, so my help might be limited.

Hi,

It’s not that difficult.
Please note that I only installed pimatic last night and that I only registered to this forum last night, so I can’t give a full-fledged solution. I just know a little about linux/debian and networks.

Install required software
Install arp-scan: sudo apt-get install arp-scan

Finding the mac address:
arp-scan can find the active devices on your network by mac address and ip-address. If your MAC address is something like AA:BB:CC:DD:EE:FF, you can give the following command:
sudo arp-scan --localnet | grep -i AA:BB:CC:DD:EE:FF

If your device is “online” you will get something like: 192.168.1.100 aacc:dd:ee:ff

finetuning this with:
sudo arp-scan --localnet | grep -i aa:bb:cc:dd:ee:ff | awk {'print $1'}
would give 192.168.144.1.100
or with:
sudo arp-scan --localnet | grep -i aa:bb:cc:dd:ee:ff | awk {'print $2'}
would give aacc:dd:ee:ff

Using a ShellSensor device with variables and rules you should always be able to detect whether the phone is “in house” or not (unless it is in deep sleep with WiFi off)

Edit: First posts did not contain block quotes. First had to find the synstax

sounds interesting, I will try this when I find the time.

I dived into it and now have the following script:

#!/bin/bash

detect=$(arp-scan --localnet | grep -i  $1 | awk {'print $1'})

# check if detect is  unset or empty
if [ -z "$detect" ];
then
	echo "not home"
else
	echo "home"
fi

and as device I have (for a person called Barak):

    {
      "id": "phone-1",
      "name": "phone-barak",
      "class": "ShellSensor",
      "attributeName": "mobile Barak",
      "attributeType": "string",
      "attributeUnit": "",
      "command": "sudo /opt/pimatic/scripts/find_phone.sh AA:BB:CC:DD:EE:FF",
      "interval": 60000
    }

In my screen I now get a simple:

mobile Barak     					home

or

mobile Barak						not home

And eventually you could add a sensor to detect the color of his house

Hi @Harry-van-der-Wolf ,

I tried arp-scan which looks really good. But I failed at a very simple thing… where to place the sh script. I’m used to my windows machine and am not very familiar with the linux path references. I didn’t want to use the /opt/ dir but my home dir to be able to modify the script via network. At the moment the script is at /Scripte/find_phone.sh. How to add this to the shellsensor?

Hi,

Did you also do a

 chmod a+x find_phone.sh

on the linux command line for your script?
On windows it needs to have extension .bat, .cmd, .com, .exe and it is “automatically” executable.
On linux/unix you need to make a file executable, and then any file can be executed regardless the extension.

Assuming you put your scripts in a scripts folder, you can create a scripts folder in your home folder or in your home/pimatic folder.
Then you can call the script using “command” in the device something like:

 "sudo /home/<username>/scripts/find_home.sh <mac-address>"

or

"sudo /home/<username>/pimatic-app/scripts/find_home.sh <mac-address>"

I personally keep scripts and “other stuff” one layer higher then my pimatic-app install (which is in /opt/pimatic/pimatic-app), to make sure that with updates, clean ups or stupid mistakes by myself, i do not remove those scripts and “other stuff”

Thank you very much, works like a charm now. You were right, I forgot the chmod…