Odroid C2/N2, Raspberry Pi Zero - Network detection script

network-detection-script.sh

#!/bin/bash

# Author: Rajat Nair (aunlead.com)
# Description: This script will periodically check -
#  - if device is on LAN
#  - if remote share is online
#  - Automount remote shares
#  - Verify if DNS resolution is working
#  - Verify if internet connectivity is working
#  - Verify if server can be pinged
#  - Verify if HTTP requests can be made
#  - Automatic log cleanup when it reaches 100MB
#  - Restart of device if it's not connected to LAN
#
# Usage -
# Edit Cron using
# crontab -e
# Copy script and give it execute permissions. To run every 30 minutes-
# */30 * * * * /opt/network/network-detection-script.sh

#
# Configurations
#
GATEWAY_CONFIGURED=$(/sbin/ip route | awk '/default/ { print $3 }' | awk 'NR == 1 {print; exit}')
GATEWAY_EXPECTED=192.168.2.1
VERIFY_DNS=$(cat /etc/resolv.conf | awk '/nameserver/ {print $2}' | awk 'NR == 1 {print; exit}')
VERIFY_DOMAIN=google.com
# Change your mountpoint according to your requirement
CUSTOM_MOUNTPOINT=/mnt
NETWORK_SHARE=192.168.2.3

#
# Logs
#
LOG_FILE=/var/log/network-script.log
TIMESTAMP=$(date +%s)
# 100 MB
LOG_SIZE=100000000

#
# When check fails do..
#
verificationFailure()
{
  # Placeholder to implement your custom notification
  # exit 1
  echo "Verification failed."
}


#
# Netcat to domain on HTTPS port
#
netcatScan()
{
  echo "Scan of $VERIFY_DOMAIN on port 443" >>${LOG_FILE}
  if nc -zw1 $VERIFY_DOMAIN 443; then
    echo "Success. $VERIFY_DOMAIN is available." >>${LOG_FILE}
  else
    echo "Failed. $VERIFY_DOMAIN is unreachable." >>${LOG_FILE}
    verificationFailure
  fi
}

#
# Ping domain
#
internetAccessVerification()
{
  echo "Pinging $VERIFY_DOMAIN to check for internet connection." >>${LOG_FILE}
  ping $VERIFY_DOMAIN -c 4
  if [ $? -eq 0 ]; then
    echo "$VERIFY_DOMAIN pingable. Internet up." >>${LOG_FILE}
  else
    echo "Internet down." >>${LOG_FILE}
    verificationFailure
    #exit 1
  fi
}

#
# Verify DNS resolution
#
dnsVerification()
{
  if [ "$VERIFY_DNS" != "run" ]; then
      echo "Name resolution of $VERIFY_DNS using first DNS server in resolv.conf" >>${LOG_FILE}
      ping "$VERIFY_DNS" -c 4
      if [ $? -eq 0 ]; then
        echo "DNS resolution successful for $VERIFY_DNS." >>${LOG_FILE}
      else
        echo "DNS resolution failed for $VERIFY_DNS." >>${LOG_FILE}
        verificationFailure
        #exit 1
      fi
    else
      echo "DNS resolution skipped" >>${LOG_FILE}
  fi
}

#
# Verify HTTP connection
#
httpVerification()
{
  echo "Verify HTTP connectivity" >>${LOG_FILE}
  case "$(curl -s --max-time 2 -I $VERIFY_DOMAIN | sed 's/^[^ ]*  *\([0-9]\).*/\1/; 1q')" in
  [23]) echo "HTTP connectivity is up" >>${LOG_FILE} ;;
  5)
    echo "Proxy error" >>${LOG_FILE}
    verificationFailure
    ;;
  *)
    echo "HTTP connectivity is down" >>${LOG_FILE}
    verificationFailure
    ;;
  esac
  #  exit 0
}

#
# Mount network shared from fstab
# if they are online
#
mountNetworkShares()
{
  ISMOUNTED=$(df -k | grep $CUSTOM_MOUNTPOINT | wc -l)
  if [ "$ISMOUNTED" -gt 0 ]; then
    echo "$CUSTOM_MOUNTPOINT has been mounted." >>${LOG_FILE}
  else
    echo "$CUSTOM_MOUNTPOINT is not mounted. Attempting to mount." >>${LOG_FILE}
    ping "$NETWORK_SHARE" -c 4
    if [ $? -eq 0 ]; then
      echo "$NETWORK_SHARE is available." >>${LOG_FILE}
      # mount -a will mount drives from /etc/fstab
      /bin/mount -a
    else
      echo "$NETWORK_SHARE is unreachable." >>${LOG_FILE}
      #exit 1
    fi
    #exit 1
  fi
}

#
# Clean up log
#
logCleanup()
{
  size="$(wc -c <"$LOG_FILE")"
  if [ "$size" -gt $LOG_SIZE ]; then
    cat /dev/null >$LOG_FILE
  fi
}


#
# Unrecoverable issue detected. Attempt reboot in 10 minutes.
# To prevent reboot loop, login within 10 minutes
# and run `/sbin/shutdown -c` to cancel it
#
catastrophicFailure()
{
  #/bin/sleep 5m
  /sbin/shutdown -r +10
}

echo "-=-=-=-=-=-=-=-=-=-=-=-=-=-=" >>${LOG_FILE}
echo "Timestamp: $TIMESTAMP" >>${LOG_FILE}
echo "Pinging gateway $GATEWAY_CONFIGURED to verify LAN connectivity" >>${LOG_FILE}
if [ "$GATEWAY_CONFIGURED" = "" ]; then
  echo "No gateway detected" >>${LOG_FILE}
  catastrophicFailure
  #exit 1
fi

if [ "$GATEWAY_CONFIGURED" != "$GATEWAY_EXPECTED" ]; then
  echo "DHCP failed." >>${LOG_FILE}
  catastrophicFailure
  #exit 1
fi

ping "$GATEWAY_CONFIGURED" -c 4

if [ $? -eq 0 ]; then
  echo "Gateway reachable. Proceeding with additional checks." >>${LOG_FILE}
  mountNetworkShares
  dnsVerification
  internetAccessVerification
  netcatScan
  httpVerification
  logCleanup
  exit 0
else
  echo "Gateway unreachable." >>${LOG_FILE}
  catastrophicFailure
  exit 1
fi