Linux is an Operating System (OS). An OS is a medium between the applications you use on your desktop and your physical machine and the hardware that is plugged into it. Other OS's that you may be familiar with may be Windows or Mac OS, or maybe a mobile one such as iOS or Android.
Linux comes in many distributions. Each distribution can be vastly different, but in EasyCTF we will be observing one of the more popular Linux distributions, Ubuntu. You can use our Ubuntu server in your browser or you can download your own copy for the full experience.
If you want to know more about any commands than we cover you can use the man command to view formatted online manual pages for the command.
man [command]So for example:
man catLinux features an interface called a shell. In a shell, you may see a prompt symbol, $ , followed by a blinking cursor _, in which you type commands and hit enter, and then the computer executes your commands and prints the output.
Before we had graphical interfaces, people typed commands into shells. Now you may be asking, "well, if we have these awesome graphical interfaces now, why still use shells?" The answer is that although you are seeing a graphical interface, all of the details of how your applications run can be manipulated through the shell. Also, most server computers only use a shell.
In EasyCTF, we have a web shell that you can log in to to solve problems and get some hands-on Linux experience. The shell page should contain your credentials for signing in.
- Windows Users - Use PuTTY to connect, using hostname
shell.easyctf.comand port22 - Mac and Linux Users - Use the
sshcommand in your terminal to connect:ssh yourusername@shell.easyctf.com 22