Interactive shell accessBidirectional file transfer

👉 Overview

👀 What ?

Interactive Shell Access and Bidirectional File Transfer is a method for remote control of a computer system. An interactive shell can accept user commands and execute them, while bidirectional file transfer allows files to be sent in both directions between two systems.

🧐 Why ?

Understanding these concepts is crucial for both cybersecurity professionals and enthusiasts. The ability to control a remote system and transfer files can be a powerful tool in the hands of a security expert, or a dangerous weapon when misused by malicious actors. Knowing how these processes work can help in developing strategies to detect and prevent unauthorized access to systems.

⛏️ How ?

To establish an interactive shell, one can use various tools and protocols, such as SSH (Secure Shell) or Telnet. Once the shell is established, commands can be sent from the controlling system to the target system. Bidirectional file transfers can be achieved using tools like SCP (Secure Copy), FTP (File Transfer Protocol), or even through the command line.

⏳ When ?

The use of interactive shell access and bidirectional file transfer techniques started as early as the advent of networked computing. However, their use in the context of cybersecurity has become more prevalent with the rise of sophisticated cyber threats.

⚙️ Technical Explanations

Interactive shell access is a technique that allows a user to remotely interact with a computer system. This remote interaction is similar to using a terminal session on the computer system itself. When an interactive shell session is established, the user can send commands from their local machine, which are then executed on the remote system. The results of these commands are then returned to the user. This entire process is facilitated by protocols such as Secure Shell (SSH), which not only ensure the connection between the local and remote system but also encrypt the communication for security purposes.

On the other hand, bidirectional file transfer is a method that allows files to be sent back and forth between two systems. This method is not limited to just sending files from the local system to the remote system, but also allows for files to be sent from the remote system to the local system. This process is typically facilitated by protocols like File Transfer Protocol (FTP) or Secure Copy Protocol (SCP). These protocols handle the logistics of transferring files, including the necessary error checking to ensure files are correctly transferred and recovery mechanisms in case of transfer failures.

For instance, let's say you want to remotely access a server using SSH and transfer a file using SCP.

1. SSH Interactive Shell Access

   To establish an SSH session, you'll first need SSH installed on both your local machine and the remote server. Once installed, you can establish an SSH session using the following command:

   ssh username@server_ip_address
   
   

   Replace username with your username on the remote server, and server_ip_address with the IP address of the server.

   After running this command, you'll be prompted to enter your password. Enter the password, and if the credentials are correct, you'll have interactive shell access to the remote server.

2. Bidirectional File Transfer

   Now, let's say you have a file named test.txt on your local machine that you want to transfer to the remote server.

   The SCP command for this would look like this:

   scp /path/to/local/test.txt username@server_ip_address:/path/to/remote/directory/
   
   

   To transfer a file from the remote server to your local machine, you can reverse the source and destination like this:

   scp username@server_ip_address:/path/to/remote/test.txt /path/to/local/directory/
   
   

   In both cases, replace the paths with the actual file paths on your local machine and remote server.

By understanding and using these commands, you can effectively control a remote system and transfer files to and from it.

🖇️ Références