Send arbitrary FTP commands in PowerShell

I've been doing plenty of stuff using PSFTP Module by Michal Gajda

Until I wanted to send arbitrary commands such as :

quote SITE LRECL=132 RECFM=FB

or

quote SYST

I have found that this can't be achieved using FtpWebRequest, but only a third-party FTP implementation.

I want to ask what is the best open source FTP implementation compatible with PowerShell?

You can send an arbitrary FTP command with WinSCP .NET assembly used from PowerShell using the Session.ExecuteCommand method:

try
{
    # Load WinSCP .NET assembly
    Add-Type -Path "WinSCPnet.dll"
 
    # Setup session options
    $sessionOptions = New-Object WinSCP.SessionOptions
    $sessionOptions.Protocol = [WinSCP.Protocol]::Ftp
    $sessionOptions.HostName = "example.com"
    $sessionOptions.UserName = "user"
    $sessionOptions.Password = "password"
 
    $session = New-Object WinSCP.Session
 
    try
    {
        # Connect
        $session.Open($sessionOptions)

        # Execute command
        $session.ExecuteCommand("SITE LRECL=132 RECFM=FB").Check() 
    }
    finally
    {
        # Disconnect, clean up
        $session.Dispose()
    }
 
    exit 0
}
catch [Exception]
{
    Write-Host $_.Exception.Message
    exit 1
}

There's also the PowerShell module build on top of WinSCP .NET assembly that you can use like:

$session = New-WinSCPSessionOptions -Protocol Ftp -Hostname example.com -Username user -Password mypassword | Open-WinSCPSession
Invoke-WinSCPCommand -WinSCPSession $session -Command "SITE LRECL=132 RECFM=FB"

(I'm the author of WinSCP)