SCP Key Setup Guide for Secure File Transfers

This guide helps you use SCP (Secure Copy Protocol) to securely transfer files between your local machine and a remote server, or between two remote systems.

What is SCP, and Why Use It?

SCP is a secure command-line tool to copy files over SSH. It encrypts both the files and any authentication information during transfer.

Why Use SCP?

• Securely transfer files over the internet
• Works with any server that supports SSH
• Simple syntax for fast file operations
• No need for setting up FTP or other services

Prerequisites

Before using SCP, you must:

1. Ensure SSH is Installed

On Linux/macOS (usually pre-installed):

ssh -V

On Windows (PowerShell 7+ or Git Bash):

ssh -V

If not installed, install OpenSSH from Windows Features or Git for Windows

2. Generate an SSH Key (if needed)

ssh-keygen -t ed25519 -C "[email protected]"

When prompted for a passphrase, you can either:

• Leave it empty (less secure, but no password prompts), or
• Set a passphrase (recommended), and follow step 3 to avoid repeated prompts.

3. Add SSH Key to SSH Agent

This step ensures your key is unlocked once per session, and avoids repeated password prompts.

eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519

If your key has a passphrase, you'll be asked to enter it once here. After that, the agent keeps it in memory.

4. Copy Your SSH Key to the Remote Server

ssh-copy-id user@server-ip

This adds your public key to the remote server so you can connect without a password.

1. Basic Syntax

scp [options] source destination

You can copy:

• From local → remote
• From remote → local
• Between two remote servers

2. Copy a File from Local to Remote

scp file.txt user@server-ip:/path/to/destination/

Sends file.txt from your computer to a directory on the remote machine

3. Copy a File from Remote to Local

scp user@server-ip:/path/to/file.txt /local/destination/

Downloads a file from the remote machine to your current directory

4. Copy a Directory Recursively

scp -r my_folder user@server-ip:/path/to/destination/

-r allows you to copy an entire folder and its contents

5. Use a Specific Port

scp -P 2222 file.txt user@server-ip:/path/

If your SSH server runs on a non-default port (not 22), specify it with -P

6. Copy Between Two Remote Hosts

scp user1@host1:/path/file.txt user2@host2:/path/

Useful for transferring files directly between two remote servers

7. Preserve File Attributes

scp -p file.txt user@server-ip:/path/

Keeps the original timestamps and modes (permissions)

8. Increase Verbosity (Debugging)

scp -v file.txt user@server-ip:/path/

Shows detailed output of the copy process — helpful for troubleshooting

SCP Cheatsheet