====== Find ip devices on network ======

This simple script pings a range of addresses to find active devices.

  #!/bin/bash
  
  #intended to loop through range of addresses and ping them to discover active devices.
  #This fails of course if a device is set to ignore icmp.
  
  #turn on debugging, -x starts, +x stops
  set +x
  
  
  #BASEIP=10.106.18
  BASEIP=192.168.1
  
  
  DNSSERVER=192.168.1.1
  
  for IPADDRESS in {1..50}
  do
          #echo "Testing >${BASEIP}.${IPADDRESS}<."
  
          #Prime Ping with a dummy ping which we ignore, timeout 2 seconds
          ping -t 2 -c1 ${BASEIP}.${IPADDRESS}  2>&1 > /dev/null
  
          #Now record the result, RC0=reply, RC1=no reply, RC2=sent but no reply (mac) 
          ping -t 2 -c1 ${BASEIP}.${IPADDRESS}  2>&1 > /dev/null
          PINGRESULT=$?
  
          if [ "${PINGRESULT}" -eq 0 ]; then
                  echo " "
                  echo "Device found on ${BASEIP}.${IPADDRESS}"
                  DNSNAME=`dig @${DNSSERVER} -x ${BASEIP}.${IPADDRESS} | grep -A1  ";; ANSWER" | grep -v ";;"` 2>&1 > /dev/null
  		LOOKUPRET=$?
  
  		if [ "${LOOKUPRET}" -eq 0 ]; then
  			echo "DNS lookup gives >${DNSNAME}<."
  		else 
  			echo "No dns lookup found"
  		fi
  
          elif [ "${PINGRESULT}" -eq 1 ]; then
                  DUMMY=1
                  echo -n "."
          elif [ "${PINGRESULT}" -eq 2 ]; then
  		#Mac rc=2 means ping sent ok, but no reply
                  DUMMY=1
                  echo -n "."
  
          else
                  echo "Unknown return code, >${PINGRESULT}<"       
  
  fi
  
  done
  echo " "
  
  
  exit 0