Rust

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.

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// 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.

let ftp = chilkat::Ftp2::new();

ftp.set_hostname("ftp.example.com");
ftp.set_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.set_password("myPassword");

// Use explicit FTPS (AUTH TLS) on the standard FTP port.
ftp.set_auth_tls(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.set_ssl_cert_requirement("SubjectCN", "ftp.example.com");

if ftp.connect().is_err() {
    println!("{}", ftp.last_error_text());
    return;
}

println!("Connected; server certificate met the requirement.");

if ftp.disconnect().is_err() {
    println!("{}", ftp.last_error_text());
    return;
}