gistfile1.sh

#!/bin/bash

if [ ! -f source.txt ] && [ ! -f destination.txt ]; then
        echo 'SOURCE & DESTINATION FILES DO NOT EXIST. EXITING.'
        exit 0
fi

echo


read -p 'SSH USERNAME: ' -r
USERNAME=$REPLY
read -p 'PORT TO CHECK: ' -r
PORT=$REPLY
echo
echo
echo '*******************'
echo 'SSH USER '$USERNAME
echo '*******************'
echo 'PORT: '$PORT
echo '*******************'
echo 'SOURCE HOSTS: '
cat source.txt
echo '*******************'
echo 'DESTINATION HOSTS'
cat destination.txt
echo '*******************'
echo

##VERIFY AGAIN
read -p 'IS THIS CORRECT (y/n)? ' -r
echo 
if [[ $REPLY =~ ^[Yy]$ ]]
then
        echo ''
elif [[ $REPLY =~ ^[nN]$ ]]
then
        echo 'EXITING BASED ON USER INPUT. NOTHING EXECUTED.'
        exit 0

else
        echo 'INVALID INPUT. EXITING. NOTHING EXECUTED.'
        exit 0
fi

echo
echo 'INITIATING PORT CHECKS'
echo 

for SOURCE_HOST in `cat source.txt` ; do
        #echo 'SOURCE: '$SOURCE_HOST
        for DESTINATION_HOST in `cat destination.txt` ; do
                echo $SOURCE_HOST' > '$PORT' > '$DESTINATION_HOST
                echo $SOURCE_HOST' > '$PORT' > '$DESTINATION_HOST >> verbose.log
                ssh -o StrictHostKeyChecking=no $USERNAME@$SOURCE_HOST "cat < /dev/tcp/$DESTINATION_HOST/$PORT"
                if [ 0 = $? ]; then
                {
                        echo 'CONNECTION ESTABLISHED'
                        echo 'CONNECTION ESTABLISHED' >> verbose.log
                        echo $SOURCE_HOST' > '$PORT' > '$DESTINATION_HOST >> complete.log
                }
                else
                {
                        echo 'CONNECTION FAILED'
                        echo 'CONNECTION FAILED' >> verbose.log
                        echo $SOURCE_HOST' > '$PORT' > '$DESTINATION_HOST >> errors.log
                }
                fi
        done
done
echo
echo 'PORT CHECKS COMPLETE'

exit 0