Linux Administration Cookbook

How it works...

When you use the -L flag with SSH, you're specifying that any connection attempts made to the local machine, on the first port listed, are to be forwarded to the remote host and port.

Let's break down the command:

[vagrant@centos1 ~]$ ssh -f -L 9999:127.0.0.1:8888 192.168.33.11 sleep 120

First, the -f and sleep 120 at the end of the command are a quick way to create a session and background it while we perform our test:

-f ... sleep 120

In the real world, you're not limited to just one Terminal window, and generally, you'll find yourself opening a session to a remote host in one window while you work in another.

The second part is the interesting bit:

-L 9999:127.0.0.1:8888

Here, we're saying that local port 9999 should have ...