There's more...

It's not just SSH that this can be used with. In the same way, we can forward ports from the remote session to our local machine  we have a wealth of options available to us.

Let's start and background a simple web server on centos1:

[vagrant@centos1 ~]$ python -m SimpleHTTPServer 8888 &
[1] 6010

Now, let's SSH to centos2, while stating that any requests made on the remote machine to 127.0.0.1:7777 are passed back along the established SSH session to centos1:

[vagrant@centos1 ~]$ ssh -R 7777:127.0.0.1:8888 192.168.33.11

On centos2, we should now be able to curl 127.0.0.1:7777 and see the contents of Vagrant's home directory on centos1:

[vagrant@centos2 ~]$ curl 127.0.0.1:7777
127.0.0.1 - - [09/Aug/2018 12:56:43] "GET / HTTP/1.1" 200 -
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html>
<title>Directory listing for /</title>
<body>
<h2>Directory listing for /</h2>
<hr>
<ul>
<li><a href=".bash_history">.bash_history</a>
<li><a href=".bash_logout">.bash_logout</a>
<li><a href=".bash_profile">.bash_profile</a>
<li><a href=".bashrc">.bashrc</a>
<li><a href=".ssh/">.ssh/</a>
</ul>
<hr>
</body>
</html>

Success!