how to copy over ssh

Secure File Transfer Methods

Introduction

Secure Shell (SSH) provides a suite of protocols for secure network communication. It's commonly used to remotely access and manage servers, and it also supports secure file transfer capabilities. This document outlines key methods for transferring files securely using SSH-based tools.

Secure Copy (SCP)

SCP is a command-line utility that utilizes the SSH protocol to transfer files between a local and a remote host, or between two remote hosts. It encrypts both the data and any passwords transmitted, providing a secure means of copying files.

SCP Syntax and Usage

The basic syntax for SCP is:

scp [options] [source] [destination]
  • Options: Modifiers to control the transfer (e.g., -r for recursive directory copying, -P to specify a port).
  • Source: The file or directory to be copied (local or remote).
  • Destination: The location to which the file or directory is copied (local or remote).

Examples:

  • Copying a local file to a remote server: scp local_file user@remote_host:/remote/directory/
  • Copying a remote file to the local machine: scp user@remote_host:/remote/file local_directory/
  • Recursively copying a local directory to a remote server: scp -r local_directory user@remote_host:/remote/directory/

SCP Security Considerations

While SCP offers secure transfer through encryption, ensure proper authentication is configured (e.g., SSH keys) to prevent unauthorized access. Regularly update your SSH client and server software to patch security vulnerabilities.

Secure FTP (SFTP)

SFTP is a file transfer protocol that also operates over the SSH protocol. It provides a secure, interactive environment for file management, including uploading, downloading, renaming, and deleting files on a remote server.

SFTP Command-Line Client

The SFTP command-line client provides an interactive interface for file transfer. It supports a range of commands similar to traditional FTP, but with the added security of SSH encryption.

Common SFTP Commands

  • get: Download a file from the remote server.
  • put: Upload a file to the remote server.
  • ls: List files in a remote directory.
  • cd: Change the remote directory.
  • pwd: Print the current remote directory.
  • rm: Delete a file on the remote server.
  • mkdir: Create a directory on the remote server.
  • rename: Rename a file on the remote server.

SFTP with Graphical Clients

Many graphical SFTP clients (e.g., FileZilla, Cyberduck, WinSCP) are available, providing a user-friendly interface for file transfer. These clients typically support drag-and-drop functionality and other features that simplify file management.

SFTP Security Considerations

Like SCP, SFTP relies on SSH for encryption and authentication. Employ strong passwords or SSH keys for authentication. Ensure the SFTP server and client software are regularly updated.

rsync over SSH

rsync is a powerful file synchronization tool that can be used in conjunction with SSH to securely and efficiently transfer files. rsync is particularly useful for transferring large files or directories, as it only transfers the differences between the source and destination.

rsync Syntax and Usage with SSH

To use rsync with SSH, specify the -e ssh option:

rsync -avz -e ssh [source] [destination]
  • -a: Archive mode; preserves permissions, ownership, timestamps, etc.
  • -v: Verbose mode; provides more detailed output.
  • -z: Compress data during transfer.
  • -e ssh: Specifies that SSH should be used as the remote shell.

Examples:

  • Synchronizing a local directory to a remote server: rsync -avz -e ssh local_directory/ user@remote_host:/remote/directory/
  • Synchronizing a remote directory to a local machine: rsync -avz -e ssh user@remote_host:/remote/directory/ local_directory/

rsync Benefits

  • Efficiency: rsync only transfers the differences between files, reducing bandwidth usage.
  • Resilience: rsync can resume interrupted transfers.
  • Flexibility: rsync offers a wide range of options for controlling the synchronization process.