Internet connectino Watchdog

this is about creating a raspberry pi based appliance that monitors your internet conenction and if it goes down, automatically debugs it and restarts stuff like modem / router etc. as necessary. the device should also be reachable via an on-demand gsm link that can be initated by sms to login to the device and debug the link manually

so far, this is just a collection of snippets of information and links, i'll write it up into a nice article one day, but not today ;)

apt update && apt install wvdial gammu gammu-smsd picocom 

• Software: Gammu
• Hardware: TP-Link MA260
• on the tp-link stick the last serial device seems to be the one that can be used for sms (gammu identify only gets information from that device).

  gammu-detect | grep -B1 TP-LINK | grep ttyUSB | tail -n 1

  to get the device name for the config

• /etc/gammu-smsdrc.template

  # Configuration file for Gammu SMS Daemon
  
  # Gammu library configuration, see gammurc(5)
  [gammu]
  port = %PORT%
  connection = at
  #logformat = textall
  
  # SMSD configuration, see gammu-smsdrc(5)
  [smsd]
  service = null
  logfile = syslog
  # Increase for debugging information
  debuglevel = 0
  RunOnReceive = /opt/process-sms.sh

• /root/.gammurc

  [gammu]
  device = %PORT%
  connection = at

• /opt/updateModemPort.sh

  updateModemPort.sh

  #!/bin/bash
  port=$(gammu-detect | grep -B1 TP-LINK | grep ttyUSB | tail -n 1 | awk -F = '{print $2}' | tr -d " ")
  sed -e "s|%PORT%|${port}|" /etc/gammu-smsdrc.template > /etc/gammu-smsdrc
  sed -e "s|%PORT%|${port}|" /root/.gammurc.template > /root/.gammurc

• installation:

  apt install gammu gammu-smsd

• process-sms.sh

  #!/bin/bash
  for i in `seq $SMS_MESSAGES` ; do
      numvar="SMS_${i}_NUMBER"
      textvar="SMS_${i}_TEXT";
      echo "${!numvar}:${!textvar}" >> /tmp/messages
      if [ "${!textvar}" == "connect" ]; then
        echo "connect!" >> /tmp/messages
      fi
  done

• Hardware: See above
• Software: wvdial
• config: /etc/wvdial.conf.template

  [Dialer Defaults]
  Init1 = ATZ
  Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
  Init3 = AT+CGDCONT=1,"IP","internet"
  Modem Type = Analog Modem
  Baud = 960000
  New PPPD = yes
  Modem = %PORT%      
  ISDN = 0
  Phone = *99#
  Password = { }
  Username = { }

• Hardware: Conrad electronics, part number 967720 (Relaiskarte 8Fach Seriell)
• Software: http://www.thomas-dohl.de/?Projekte___Relaiskarte

• via dual prolific basead usb to serial converter, one link goes to the relay card, the other to the serial terminal of the pfsense router.
• usb link is extended down to the basement via cat7 link, I simply cut a usb extension cord into two and attached RJ45 plugs to both ends with identical pin layout. works like a charm :)
• software: picocom