Objective-C

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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Objective-C

#import <CkoFtp2.h>

BOOL success = NO;

CkoFtp2 *ftp = [[CkoFtp2 alloc] init];

ftp.Hostname = @"ftp.example.com";
ftp.Username = @"myFtpLogin";

//  SocksVersion selects the proxy: 0 (default) = none, 4 = SOCKS4, 5 = SOCKS5.
ftp.SocksVersion = [NSNumber numberWithInt:5];
ftp.SocksHostname = @"socks.example.com";
ftp.SocksPort = [NSNumber numberWithInt:1080];

//  SOCKS5 supports username/password authentication; SOCKS4 uses only a user identifier.
ftp.SocksUsername = @"myProxyLogin";
ftp.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.Password = @"myPassword";

success = [ftp Connect];
if (success == NO) {
    NSLog(@"%@",ftp.LastErrorText);
    return;
}

NSLog(@"%@",@"Connected through the SOCKS proxy.");

success = [ftp Disconnect];
if (success == NO) {
    NSLog(@"%@",ftp.LastErrorText);
    return;
}