SSH Tunnel example to access http server on private AWS network

ssh-tunnelling.sh

// Goal:  Be able to do a curl from local to  server in AWS private subnet
// Host - The machine running the server in a private subnet
// Bastion - A machine which has access to the Host in the private subnet. You need to have SSH access to this machine
// Local - Your local machine

// Normally, if you SSH into your Bastion, you are able to curl the DNS/IP of the private Host machine running your server
// To be able to curl from your local machine, you'll need to set up a tunnel between your local and the bastion
// When you tunnel, you have to provide the DNS/IP of the private Host as seen from the Bastion. This will typically be a private IP
// an internal DNS name

// Run on local computer to set up tunnel from local to bastion 

ssh -i <keypair> -f ec2-user@<bastionIP> -L <localPort>:<privateHostName>:<hostPort> -N

// localPort - the port you want to expose the Host's server on your local machine
// privateHostName - the hostname/IP of the Host running the server
// hostPort - the port of the server running on the Host

// You are now able to curl from your local machine via localhost and localPort
curl http://localhost:<localPort>

// To see the list of all tunnelled connections
// make sure you kill the tunnel once you are done using it
ps aux | grep ssh