connect_to_private_ec2_instance.sh

#! /bin/bash

port=8022
nat_ip=10.0.0.1
nat_key=~/.ssh/nat.pem
target_key=~/.ssh/private_machine.pem
reuse=0

ssh-keygen -f ~/.ssh/known_hosts -R [localhost]:$port

while getopts "r" opt; do
  case $opt in
    r)
      reuse=1
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit
      ;;
  esac
done

if [ $reuse -eq 0 ];
then
  pid=$(netstat -ltpn 2> /dev/null | grep $port | awk '{print $7}' | tr '\n' ' ' | awk '{print $1}' | cut -d '/' -f1)
  if [ "$pid" != "" ];
  then
    echo "Killing previous tunnel: $pid"
    kill -9 $pid
  fi
  ssh -fNL $port:$1:22 ec2-user@$nat_ip -i $nat_key
fi

ssh -o StrictHostKeyChecking=no -i $target_key -p $port ubuntu@localhost