PowerShell

Require Specific FTPS Server Certificate Fields

Demonstrates the Chilkat Ftp2.SetSslCertRequirement method, which adds a required match against the FTP server certificate. The first argument selects the certificate field (such as SubjectCN or IssuerCN) and the second is the required value. It is a void method; a non-matching certificate causes the connection to fail.

Background: Standard TLS validation confirms a certificate is trusted and valid for the hostname, but it does not guarantee you reached the specific server you expect — a form of pinning closes that gap. Requiring a certificate field to match a known value rejects any certificate that does not, defending against a mis-issued or substituted certificate even if it would otherwise pass validation. Multiple requirements can be added, and all must be satisfied.

Chilkat PowerShell Downloads

Download Chilkat for PowerShell

PowerShell

Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

#  Demonstrates the Ftp2.SetSslCertRequirement method, which adds a required match against the FTP
#  server certificate.  The 1st argument selects the certificate field and the 2nd is the required
#  value.  It is a void method.

$ftp = New-Object Chilkat.Ftp2

$ftp.Hostname = "ftp.example.com"
$ftp.Username = "myFtpLogin"

#  Normally you would not hard-code the password in source.  You should instead obtain it
#  from an interactive prompt, environment variable, or a secrets vault.
$ftp.Password = "myPassword"

#  Use explicit FTPS (AUTH TLS) on the standard FTP port.
$ftp.AuthTls = $true

#  Require that the server certificate's subject common name matches an expected value.  If the
#  presented certificate does not match, the TLS connection fails.  Supported fields include
#  SubjectDN, SubjectCN, IssuerDN, IssuerCN, and others.
$ftp.SetSslCertRequirement("SubjectCN","ftp.example.com")

$success = $ftp.Connect()
if ($success -eq $false) {
    $($ftp.LastErrorText)
    exit
}

$("Connected; server certificate met the requirement.")

$success = $ftp.Disconnect()
if ($success -eq $false) {
    $($ftp.LastErrorText)
    exit
}