SSH (Secure Shell)

Here’s a step-by-step guide on how to use SSH as a beginner:

1. Open a Terminal (Linux and macOS) or Use an SSH Client (Windows):

• On Linux and macOS, you can open a terminal window. On Windows, you can use an SSH client like PuTTY or the built-in Windows Subsystem for Linux (WSL).

2. Connect to a Remote Server:

• To connect to a remote server, use the ssh command followed by the username and IP address or domain name of the remote server. For example:
  ssh username@remote_server_ip


  Replace username with your remote server’s username and remote_server_ip with the server’s IP address or domain name.

3. Authenticate:

• After running the ssh command, you’ll be prompted to enter your password for the remote server. Type your password (characters won’t be displayed as you type) and press Enter. Alternatively, you can use SSH key-based authentication for enhanced security.

4. Navigate and Execute Commands:

• Once connected, you’ll have access to the remote server’s command-line interface. You can navigate directories, list files, and execute commands just like you would on your local machine. For example, you can use ls to list files and cd to change directories.

5. Exit SSH Session:

• To exit the SSH session and return to your local terminal or SSH client, you can type the following command:
  exit


Using SSH Key-Based Authentication (Optional, but Recommended):

For improved security and convenience, consider using SSH key-based authentication instead of passwords. Here’s how to set it up:

1. Generate SSH Key Pair:

• On your local machine, open a terminal and use the following command to generate an SSH key pair (public and private keys):
  ssh-keygen

• Follow the prompts to specify the key location and set a passphrase (optional but recommended for added security).

2. Copy the Public Key to the Remote Server:

• Use the ssh-copy-id command to copy your public key to the remote server, replacing username and remote_server_ip with the appropriate values:
  ssh-copy-id username@remote_server_ip


3. Test Key-Based Authentication:

• Try connecting to the remote server again using SSH. You should be able to log in without entering a password, provided that you’ve correctly set up key-based authentication.

4. Secure SSH Configuration (Optional, but Recommended):

• To enhance security, you can modify the SSH server’s configuration file (sshd_config) on the remote server to disallow password-based authentication and allow only key-based authentication.

Note: Be cautious when using SSH to connect to remote servers, especially if you are not the server administrator. Always use SSH for legitimate and authorized purposes. Unauthorized access or misuse of SSH can have legal consequences.

By following these steps, you can use SSH to securely access remote servers, execute commands, and transfer files. SSH is a powerful tool for managing remote systems and is widely used in various IT and development tasks. 

Common SSH Commands

Here are some common SSH commands you can use to perform various tasks when connected to a remote server:

1. File Transfer with SCP:

• SCP (Secure Copy Protocol) allows you to securely transfer files between your local machine and a remote server. To copy a local file to the remote server, use the following command:
  scp /path/to/local/file username@remote_server_ip:/path/to/remote/location/

• To copy a file from the remote server to your local machine:
  scp username@remote_server_ip:/path/to/remote/file /path/to/local/location/


2. List Files and Directories:

• Use the following commands to list files and directories on the remote server:
  • List files in the current directory:
    ls

  • List files with detailed information (including permissions and sizes):
    ls -l

  • List all files, including hidden ones:
    ls -a


3. Change Directory:

• To navigate to a different directory on the remote server, use the cd command. For example:
  cd /path/to/directory


4. Create a Directory:

• To create a new directory on the remote server, use the mkdir command:
  mkdir new_directory_name


5. Remove Files and Directories:

• To delete a file, use the rm command:
  rm filename

• To delete a directory and its contents, use the -r flag with rm:
  rm -r directory_name


6. Copy, Move, and Rename Files:

• To copy a file, use the cp command:
  cp source_file destination

• To move or rename a file, use the mv command:
  mv old_filename new_filename


7. View File Contents:

• To view the contents of a file without editing it, you can use the cat or less command:
  cat filename


  or

  less filename


8. Edit Files: – You can use text editors like nano, vim, or emacs to edit files on the remote server. For example: nano filename

9. Check Disk Usage: – To check disk usage on the remote server, use the df (disk free) command: df -h

10. Check System Information: – To view information about the remote server, including its hardware and operating system, you can use the uname command: uname -a

11. Process Management: – To manage processes on the remote server, you can use commands like ps, kill, and top to list, terminate, and monitor running processes.

These are some of the most common SSH commands for interacting with remote servers.