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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Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Ftp2;

public class ChilkatExample {

    public static void main(String[] args) {
        Ftp2 ftp = new Ftp2();

        ftp.setHostname("ftp.example.com");
        ftp.setUsername("myFtpLogin");

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

        // SOCKS5 supports username/password authentication; SOCKS4 uses only a user identifier.
        ftp.setSocksUsername("myProxyLogin");
        ftp.setSocksPassword("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.setPassword("myPassword");

        try {
            ftp.connect();
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

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

        try {
            ftp.disconnect();
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }
    }
}