Java

Connect to FTP Through a SOCKS Proxy

Demonstrates connecting through a SOCKS proxy using SocksVersion, SocksHostname, SocksPort, SocksUsername, and SocksPassword.

Background: SOCKS is a general-purpose TCP relay, so it carries FTP transparently. SocksVersion is the switch — 0 disables it, while 4 or 5 selects the protocol. SOCKS5 supports username/password authentication and is the usual choice; SOCKS4 supports only a user identifier. Because FTP opens separate data connections, a SOCKS proxy combined with passive mode is generally the most reliable arrangement.

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Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    CkFtp2 ftp = new CkFtp2();

    ftp.put_Hostname("ftp.example.com");
    ftp.put_Username("myFtpLogin");

    //  SocksVersion selects the proxy: 0 (default) = none, 4 = SOCKS4, 5 = SOCKS5.
    ftp.put_SocksVersion(5);
    ftp.put_SocksHostname("socks.example.com");
    ftp.put_SocksPort(1080);

    //  SOCKS5 supports username/password authentication; SOCKS4 uses only a user identifier.
    ftp.put_SocksUsername("myProxyLogin");
    ftp.put_SocksPassword("myProxyPassword");

    //  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.put_Password("myPassword");

    success = ftp.Connect();
    if (success == false) {
        System.out.println(ftp.lastErrorText());
        return;
        }

    System.out.println("Connected through the SOCKS proxy.");

    success = ftp.Disconnect();
    if (success == false) {
        System.out.println(ftp.lastErrorText());
        return;
        }
  }
}