It’s a way of channeling your network traffic on a specific port through an encrypted ssh session via a third server. There are rare occasion where you absolutely want or need this, but will forget how to do it in between. Hence these scripts.
Here is a use case scenario: you’re at work and need to ssh into your personal web server, but there is a corporate firewall in the way. It blocks all traffic, except on port 80 and 443. Shit out of luck? Nope.
If you are clever, you have probably envisioned this, and set up a box at home (or spooled up a VM somewhere outside work) that listens for ssh connections on port 443, so you can ssh into that, and from your server. That’s good and all, but what if you need to scp some files to it?
Enter the tunnels: you establish an ssh tunnel to your home box (let’s call it a bounce server) and then you can use that tunnel to use and ssh, scp directly.
You will probably need the color script to make these work.
Here they are:
First you need to create a tunnel. Going with our use case, lets say you want to access destination.host.org and you have already set up home.box.net at home to listen for ssh connections on port 443. Open a terminal window and create a tunnel:
tunnel-create home.box.net destination.host.org 443
To ssh into your destination, just use:
tunnel-ssh myusername
Let’s say you have file.txt you want to upload to /var/www/ on your destination:
tunnel-put ./file.txt /var/www myusername
If you want to grab same file from the destination:
tunnel-get /var/www/file.txt . myusername
In all of the above you can skip the username if it happens to be the same on the destination box as it is on your current machine.