Objective-C

SSH Through a SOCKS Proxy

Demonstrates connecting to an SSH server through a SOCKS4 or SOCKS5 proxy. Set the SOCKS properties before calling Connect, and set SocksVersion to match the proxy server.

Background: SOCKS is a general-purpose TCP relay, so unlike an HTTP proxy it is designed from the start to carry arbitrary protocols — usually the smoother option for SSH. The version matters: SOCKS4 supports only a username with no password, while SOCKS5 supports full login/password authentication as well as IPv6 and remote DNS resolution. Note this is the inverse of dynamic port forwarding: here a SOCKS proxy is used to reach the SSH server, rather than SSH providing a SOCKS proxy.

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Objective-C

#import <CkoSsh.h>
#import <NSString.h>

BOOL success = NO;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

//  Demonstrates connecting to an SSH server through a SOCKS4 or SOCKS5 proxy.

CkoSsh *ssh = [[CkoSsh alloc] init];

//  Set the SOCKS proxy properties before connecting.  The hostname may be a domain name or an
//  IP address.
ssh.SocksHostname = @"socks.example.com";
ssh.SocksPort = [NSNumber numberWithInt:1080];
ssh.SocksUsername = @"mySocksLogin";
ssh.SocksPassword = @"mySocksPassword";

//  Set the version to match the proxy server: 4 or 5.
//  Note: SOCKS4 supports only a username, with no password.  SOCKS5 supports full
//  login/password authentication.
ssh.SocksVersion = [NSNumber numberWithInt:5];

NSString *hostname = @"ssh.example.com";
int port = 22;
success = [ssh Connect: hostname port: [NSNumber numberWithInt: port]];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

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

//  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.
NSString *password = @"mySshPassword";

success = [ssh AuthenticatePw: @"mySshLogin" password: password];
if (success == NO) {
    NSLog(@"%@",ssh.LastErrorText);
    return;
}

//  ... use the SSH connection normally ...

[ssh Disconnect];