Table of Contents

Intro

On Linux sometimes we need to see what hashcat is doing via SSH. By default you can't attach to the same console terminal (tty1, tty2 etc.) However, there is secure option for that called Screen.

Requirements

On this example will be covered only Ubuntu, as it most used by inexpierenced people:

  sudo apt-get install openssh-server openssh-client
  • Program screen
  sudo apt-get install screen
  

Usage

Usage of screen program is super simple. If you plan to use it you should start it before any other process (on this case GPGPU application). After program launch, you will get virtual console with it's own PID. To create a new virtual terminal enter:

screen -S name

To detach from a running virtual terminal we use:

CTRL+AD

To attach back (bearing in mind that we have only one virtual terminal running)

screen -x

If running more than one virtual terminal, we need to know it's PID, or the name you have chosen before as invoking screen -x will give us similar output

There are several suitable screens on:
	19814.pts-0.sl1	(09/19/11 15:28:06)	(Detached)
	12239.pts-0.sl1	(09/10/11 15:02:29)	(Detached)
	1942.name	(09/10/11 17:05:40)	(Detached)
Type "screen [-d] -r [pid.]tty.host" to resume one of them.

So knowing time or PID or name of needed terminal (for example first terminal) we invoke it by typing

screen -r 19814
or
screen -x name

Conclusion

Using Screen effectively not only allows us to attach into an already running terminal, but also eliminates the possibility of data loss when you are using unstable connection, (GPRS, WiMax) as after communication loss without Screen you will lose the process which was running on that terminal.