The use of ssh has some limitations to what you can do with a single terminal until you learn the screen command. 

This command allows you to create a virtual terminal which permits the creation of additional multiplexed terminal sessions within the context of the single ssh terminal window displayed on the connecting users system. 

This concept is not the easiest to follow but lets try to explain this in a easier to understand language. 

When you connect to a server using ssh you are given a single terminal on that remote system and if you need additional terminals to launch commands while the original terminal window is consumed with active output from a command as example:

    tcpdump -v -i eth0     # cmdline sniffing

With the command above your display would be update regularly with output captured from the ethernet interface and would not allow you to launch more commands and in retrospect would require an additional SSH session to give the end user the ability to monitor the interface traffic and continue to launch commands on the remote system.

Now that you understand that having a bunch of ssh terminals open to remote systems can be cumbersome and not that practical as well it is  difficult to keep track of them, thus we give you screen. Lets get started shall we?

In a terminal on your local *nix system lets issue the following command:


This should produce some output in your terminal as follows: