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Upcoming Project: LED IP Status Indicator. How?

Kuya.Marc

The Situation

 

I've configured my Broadband Internet Router to have fixed DHCP addresses for allowed devices (being used by household relatives). Before shutting off the Internet (so I can sleep), I typically ping IP addresses to see if they're connected. These are Wi-Fi connections, therefore, I can't physically see a LED light up on the router, itself.

 

The Configuration

 

I have the Raspberry Pi, Model B at 512MB, that has a physical LAN connect to my Broadband Internet Router, which also is a Wi-Fi access point. I am able to manually ping IP addresses when logging in via SSH.

 

The Project

 

Having a LED (connected via GPIO with resistor) light up when a specific IP address is active, without requiring a SSH or direct login. In other words, its a hardware version of the ping utility.

 

The Questions

 

  1. Can this be a BASH script that runs without SSH login?
  2. Can this be compiled from C source code? (I'm not used to Python, yet.)
  3. Can this run as a system service, whereas it's transparent to Raspberry Pi operations (Raspbian, XBMC, etc.)?

 

The Summary

 

I am not asking someone to write the code as I'm a veteran C programmer with 15+ years of Linux experience. I've never written code to test, and constantly retest of a specific IP address is alive or not. This project may be anywhere from extremely easy to extremely hard, but I know the Raspberry Pi can do it.

 

I will give credit to those that wish to make the initial code for me, as this project can be beneficial in many ways, such as checking if a specific device (computer, smartphone, etc.) is online or not.  Thanks in advance!

 

Kuya Marc

  • in reply to Kuya.Marc

    I just saw your post, sorry for my late reply.
    How about you open your router's attached devices page and parse it for the MAC address you are checking for?

  • in reply to gregoryfenton

    So, while I was playing dumb and pretended that we know the IP address of the device in question, you are now pretending/assuming we know the mac address.

     

    But the problem remains a generic one. It seems we're looking for a specific device, how do we recognize that device?

  • in reply to rew

    You both are right. First we need to know the device which is connecting with Raspberry Pi. I made RPi access point following this guide. I think we need to check the log file to get the IP of the device first and using that IP we can turn ON the LED connected with GPIO but I don't know how to do that.

  • in reply to jhz

    My ISC-DHCPD shows:

    Jan 26 13:40:14 myserver dhcpd[6871]: DHCPACK on 192.168.xxx.yy to xx:yy:zz:49:62:08 via enp4s0

    in the /var/log/syslog file when a DHCP lease is given out or extended.

     

    So with

    tail -f /var/log/syslog | awk  '/DHCPACK/ { system ("/home/pi/ip_given_out"  $8 );}'

    you can have a script (/home/pi/ip_given_out) run with as an argument the IP address that was just given out. You can save that to a file

    LASTIP_FILE=/home/pi/.lastip

    echo $1 > $LASTIP_FILE

    and then use

    the_IP=`cat $LASTIP_FILE`

    in the script I've typed (and not tested) above. (some merging/mangling still required. Left as an excercise for the reader).