PowerShell SSH and File Transfer

A comprehensive PowerShell script for SSH connections and secure file transfers.

Features

• Multiple Transfer Methods:

  • Native OpenSSH (SCP) - Built into Windows 10/11
  • Posh-SSH Module (SFTP/SCP) - More features and control

• Flexible Operations:

  • Upload files to remote server
  • Download files from remote server
  • Execute remote SSH commands
  • SSH key authentication support
  • Custom port support

Prerequisites

Method 1: Native OpenSSH (Recommended for Windows 10+)

1. Enable OpenSSH Client (Windows 10/11):

   # Run as Administrator
   Add-WindowsCapability -Online -Name OpenSSH.Client~~~~0.0.1.0

2. Verify Installation:

   ssh -V

Method 2: Posh-SSH Module

# Install Posh-SSH module
Install-Module -Name Posh-SSH -Force -Scope CurrentUser

Quick Start

1. Upload a File

# Using native SCP
Transfer-FileWithSCP `
    -HostName "server.example.com" `
    -UserName "myuser" `
    -LocalPath "C:\Documents\report.pdf" `
    -RemotePath "/home/myuser/report.pdf" `
    -Direction "Upload"

2. Download a File

# Using native SCP
Transfer-FileWithSCP `
    -HostName "server.example.com" `
    -UserName "myuser" `
    -LocalPath "C:\Downloads\backup.zip" `
    -RemotePath "/home/myuser/backups/backup.zip" `
    -Direction "Download"

3. Using SSH Keys

# Upload with private key authentication
Transfer-FileWithSCP `
    -HostName "server.example.com" `
    -UserName "myuser" `
    -LocalPath "C:\data\file.txt" `
    -RemotePath "/home/myuser/file.txt" `
    -PrivateKeyPath "C:\Users\myuser\.ssh\id_rsa" `
    -Direction "Upload"

4. Execute Remote Commands

# Run a command on remote server
$output = Invoke-SSHCommand `
    -HostName "server.example.com" `
    -UserName "myuser" `
    -Command "df -h"

Write-Host $output

5. Transfer Multiple Files

# Upload multiple files
$files = Get-ChildItem "C:\Documents\*.pdf"

foreach ($file in $files) {
    Transfer-FileWithSCP `
        -HostName "server.example.com" `
        -UserName "myuser" `
        -LocalPath $file.FullName `
        -RemotePath "/home/myuser/documents/$($file.Name)" `
        -Direction "Upload"
}

Function Reference

Transfer-FileWithSCP

Upload or download files using native OpenSSH SCP.

Parameters:

• HostName (required): Remote server hostname or IP
• UserName (required): SSH username
• LocalPath (required): Local file path
• RemotePath (required): Remote file path
• Port (optional): SSH port (default: 22)
• Direction (required): 'Upload' or 'Download'
• PrivateKeyPath (optional): Path to private key file

Transfer-FileWithPoshSSH

Upload or download files using Posh-SSH module (SFTP).

Parameters:

• HostName (required): Remote server hostname or IP
• UserName (required): SSH username
• Password (required): SSH password
• LocalPath (required): Local file path
• RemotePath (required): Remote file path
• Port (optional): SSH port (default: 22)
• Direction (required): 'Upload' or 'Download'

Invoke-SSHCommand

Execute commands on remote server using native SSH.

Parameters:

• HostName (required): Remote server hostname or IP
• UserName (required): SSH username
• Command (required): Command to execute
• Port (optional): SSH port (default: 22)
• PrivateKeyPath (optional): Path to private key file

Invoke-SSHCommandWithPoshSSH

Execute commands using Posh-SSH module.

Parameters:

• HostName (required): Remote server hostname or IP
• UserName (required): SSH username
• Password (required): SSH password
• Command (required): Command to execute
• Port (optional): SSH port (default: 22)

Advanced Examples

Transfer Directory Contents

# Upload all files from a directory
$sourceDir = "C:\Projects\website"
$targetDir = "/var/www/html"

Get-ChildItem -Path $sourceDir -Recurse -File | ForEach-Object {
    $relativePath = $_.FullName.Substring($sourceDir.Length)
    $remotePath = "$targetDir$($relativePath -replace '\\', '/')"

    Transfer-FileWithSCP `
        -HostName "webserver.com" `
        -UserName "webadmin" `
        -LocalPath $_.FullName `
        -RemotePath $remotePath `
        -Direction "Upload"
}

Automated Backup Script

# Daily backup script
$date = Get-Date -Format "yyyy-MM-dd"
$backupFile = "C:\Backups\backup-$date.zip"
$remoteBackupDir = "/home/user/backups"

# Create backup
Compress-Archive -Path "C:\Data\*" -DestinationPath $backupFile

# Upload to server
Transfer-FileWithSCP `
    -HostName "backup-server.com" `
    -UserName "backupuser" `
    -LocalPath $backupFile `
    -RemotePath "$remoteBackupDir/backup-$date.zip" `
    -PrivateKeyPath "C:\Users\user\.ssh\backup_key" `
    -Direction "Upload"

# Verify on remote server
$remoteFiles = Invoke-SSHCommand `
    -HostName "backup-server.com" `
    -UserName "backupuser" `
    -Command "ls -lh $remoteBackupDir" `
    -PrivateKeyPath "C:\Users\user\.ssh\backup_key"

Write-Host "Remote backup files:" -ForegroundColor Green
Write-Host $remoteFiles

Progress Monitoring for Large Files

# For large files, use Posh-SSH with progress monitoring
function Transfer-LargeFile {
    param($HostName, $UserName, $Password, $LocalPath, $RemotePath)

    Write-Host "Transferring large file: $LocalPath" -ForegroundColor Yellow

    Transfer-FileWithPoshSSH `
        -HostName $HostName `
        -UserName $UserName `
        -Password $Password `
        -LocalPath $LocalPath `
        -RemotePath $RemotePath `
        -Direction "Upload"
}

Troubleshooting

Common Issues

1. "ssh: command not found"

   • OpenSSH Client is not installed
   • Solution: Run Add-WindowsCapability -Online -Name OpenSSH.Client~~~~0.0.1.0 as Administrator

2. "Permission denied (publickey)"

   • SSH key authentication failed
   • Solution: Check private key permissions and ensure public key is in ~/.ssh/authorized_keys on remote server

3. "Connection refused"

   • SSH service not running or firewall blocking
   • Solution: Verify SSH service is running on remote server and port 22 (or custom port) is open

4. "Host key verification failed"

   • Host key not in known_hosts
   • Solution: Run ssh-keyscan server.com >> ~/.ssh/known_hosts or connect manually first

Enable SSH Debugging

# Add -v flag for verbose output
& ssh -v user@server.com

# For SCP, add -v flag
& scp -v file.txt user@server.com:/path/

Security Best Practices

1. Use SSH Keys Instead of Passwords

   # Generate SSH key pair
   ssh-keygen -t ed25519 -C "[email protected]"
   
   # Copy public key to server
   type $env:USERPROFILE\.ssh\id_ed25519.pub | ssh user@server.com "cat >> ~/.ssh/authorized_keys"

2. Protect Private Keys

   • Store private keys in ~/.ssh/ directory
   • Set appropriate permissions (Windows: Remove inheritance, keep only your user)

3. Use Strong Passwords

   • When using password authentication, use strong, unique passwords
   • Consider using SecureString in scripts:

   $securePassword = Read-Host "Enter password" -AsSecureString

4. Limit Access

   • Configure SSH server to use key-only authentication
   • Disable root login
   • Use non-standard SSH ports when possible

License

This script is provided as-is for educational and practical use.

Contributing

Feel free to submit issues and enhancement requests!