Verify FTP SSL Server Certificate

Download: Chilkat .NET Assemblies

This example demonstrates how to verify the FTP server's certificate and authenticity. The intent is to verify the authenticity of the server before passing a login/password to it.

Chilkat.Ftp2 ftp = new Chilkat.Ftp2();

bool success;

//  Any string unlocks the component for the 1st 30-days.
success = ftp.UnlockComponent("Anything for 30-day trial");
if (success != true) {
    MessageBox.Show(ftp.LastErrorText);
    return;
}

ftp.Hostname = "ftp.myftpserver.com";
ftp.Username = "myUsername";
ftp.Password = "myPassword";

//  Establish an AUTH SSL secure channel after connection
//  on the standard FTP port 21.
ftp.AuthSsl = true;

//  The Ssl property is for establishing an implicit SSL connection
//  on port 990.  Do not set it.
ftp.Ssl = false;

//  Indicate that the FTP server must have a verifiable SSL certificate.
//  Do not accept self-signed certs or certificates that are
//  expired, revoked, or cannot be verified to a root authority:
ftp.RequireSslCertVerify = true;

//  You may also set a requirement.  In this example,
//  the certificate's Common Name (CN) must match the
//  required string exactly:
ftp.SetSslCertRequirement("subjectcn","Chilkat Software, Inc.");

//  Connect and login to the FTP server.
success = ftp.Connect();
if (success != true) {
    MessageBox.Show(ftp.LastErrorText);
    return;
}
else {
    //  LastErrorText contains information even when
    //  successful. This allows you to visually verify
    //  that the secure connection actually occurred.
    textBox1.Text += ftp.LastErrorText + "\r\n";
    textBox1.Refresh();
}

//  After logging on, you may examine the FTP server's cert:
Chilkat.Cert cert;
cert = ftp.GetSslServerCert();
if (cert == null ) {
    MessageBox.Show("No server certificate!");
}
else {
    //  Display the distinguished name of the SSL cert.
    MessageBox.Show(cert.SubjectDN);
}

MessageBox.Show("Secure FTP Channel Established!");

//  Do whatever you're doing to do ...
//  upload files, download files, etc...

ftp.Disconnect();