C

FTP through SSH Tunnel with Dynamic Port Forwarding

See more FTP Examples

Demonstrates how to start a background thread that runs a portable SSH tunnel w/ dynamic port forwarding that the foreground thread can be used for establishing FTP sessions through an SSH tunnel.

Note: Some developers may be accustomed to starting an stunnel.exe proxy from https://www.stunnel.org. The stunnel.exe is not necessary here. Chilkat's background thread fulfills the task of what the external stunnel.exe does. Therefore, your application is self-contained, meaning that it can run anywhere because the SSH tunnel proxy is built-in.

C

#include <C_CkSshTunnel.h>
#include <C_CkFtp2.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSshTunnel tunnel;
    const char *sshHostname;
    int sshPort;
    HCkFtp2 ftp;
    const char *localFilename;
    const char *remoteFilename;
    BOOL waitForThreadExit;

    success = FALSE;

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

    success = FALSE;

    tunnel = CkSshTunnel_Create();

    sshHostname = "sftp.example.com";
    sshPort = 22;

    // Connect to an SSH server and establish the SSH tunnel:
    success = CkSshTunnel_Connect(tunnel,sshHostname,sshPort);
    if (success != TRUE) {
        printf("%s\n",CkSshTunnel_lastErrorText(tunnel));
        CkSshTunnel_Dispose(tunnel);
        return;
    }

    // Authenticate with the SSH server via a login/password
    // or with a public key.  
    // This example demonstrates SSH password authentication.
    success = CkSshTunnel_AuthenticatePw(tunnel,"mySshLogin","mySshPassword");
    if (success != TRUE) {
        printf("%s\n",CkSshTunnel_lastErrorText(tunnel));
        CkSshTunnel_Dispose(tunnel);
        return;
    }

    // Indicate that the background SSH tunnel thread will behave as a SOCKS proxy server
    // with dynamic port forwarding:
    CkSshTunnel_putDynamicPortForwarding(tunnel,TRUE);

    // We may optionally require that connecting clients authenticate with our SOCKS proxy server.
    // To do this, set an inbound username/password.  Any connecting clients would be required to 
    // use SOCKS5 with the correct username/password.
    // If no inbound username/password is set, then our SOCKS proxy server will accept both
    // SOCKS4 and SOCKS5 unauthenticated connections.

    CkSshTunnel_putInboundSocksUsername(tunnel,"chilkat123");
    CkSshTunnel_putInboundSocksPassword(tunnel,"password123");

    // Start the listen/accept thread to begin accepting SOCKS proxy client connections.
    // Listen on port 1080.
    success = CkSshTunnel_BeginAccepting(tunnel,1080);
    if (success != TRUE) {
        printf("%s\n",CkSshTunnel_lastErrorText(tunnel));
        CkSshTunnel_Dispose(tunnel);
        return;
    }

    // Now that a background thread is running a SOCKS proxy server that forwards connections
    // through an SSH tunnel, it is possible to use any Chilkat implemented protocol that is SOCKS capable,
    // such as HTTP, POP3, SMTP, IMAP, FTP, etc.  The protocol may use SSL/TLS because the SSL/TLS
    // will be passed through the SSH tunnel to the end-destination.  Also, any number of simultaneous
    // connections may be routed through the SSH tunnel.

    ftp = CkFtp2_Create();

    // Indicate that the HTTP object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
    CkFtp2_putSocksHostname(ftp,"localhost");
    // The SocksPort must equal the port passed to BeginAccepting above.
    CkFtp2_putSocksPort(ftp,1080);
    CkFtp2_putSocksVersion(ftp,5);
    // The SOCKS5 login/password set here must equal the InboundSocksUsername/Password set above.
    CkFtp2_putSocksUsername(ftp,"chilkat123");
    CkFtp2_putSocksPassword(ftp,"password123");

    // This is the actual FTP server domain or IP address, and the login/password for the user account on the destination FTP server.
    CkFtp2_putHostname(ftp,"ftp.someFtpServer.com");
    CkFtp2_putUsername(ftp,"myLogin");
    CkFtp2_putPassword(ftp,"myPassword");
    CkFtp2_putAuthTls(ftp,TRUE);

    // Connect and login (via the SSH tunnel) to the FTP server.
    success = CkFtp2_Connect(ftp);
    if (success != TRUE) {
        printf("%s\n",CkFtp2_lastErrorText(ftp));
        CkSshTunnel_Dispose(tunnel);
        CkFtp2_Dispose(ftp);
        return;
    }

    // Change to the remote directory where the file is located.
    // This step is only necessary if the file is not in the root directory
    // for the FTP account.
    success = CkFtp2_ChangeRemoteDir(ftp,"junk");
    if (success != TRUE) {
        printf("%s\n",CkFtp2_lastErrorText(ftp));
        CkSshTunnel_Dispose(tunnel);
        CkFtp2_Dispose(ftp);
        return;
    }

    localFilename = "c:/temp/hamlet.xml";
    remoteFilename = "hamlet.xml";

    // Download a file.  (the data connection is also automatically established through the 
    // SSH tunnel using dynamic port forwarding..)
    success = CkFtp2_GetFile(ftp,remoteFilename,localFilename);
    if (success != TRUE) {
        printf("%s\n",CkFtp2_lastErrorText(ftp));
        CkSshTunnel_Dispose(tunnel);
        CkFtp2_Dispose(ftp);
        return;
    }

    // The disconnect is disconnecting with the FTP server and closes the SSH tunnel.
    // The background tunnel thread is still running, and may be used for subsequent FTP connections,
    // or even connections for any other purpose, such as HTTP, IMAP, SMTP, POP3, etc.
    success = CkFtp2_Disconnect(ftp);

    // When the app is finished with the tunnel, it can cleanup..

    // Stop the background listen/accept thread:
    waitForThreadExit = TRUE;
    success = CkSshTunnel_StopAccepting(tunnel,waitForThreadExit);
    if (success != TRUE) {
        printf("%s\n",CkSshTunnel_lastErrorText(tunnel));
        CkSshTunnel_Dispose(tunnel);
        CkFtp2_Dispose(ftp);
        return;
    }

    // Close the SSH tunnel (would also kick any remaining connected clients).
    success = CkSshTunnel_CloseTunnel(tunnel,waitForThreadExit);
    if (success != TRUE) {
        printf("%s\n",CkSshTunnel_lastErrorText(tunnel));
        CkSshTunnel_Dispose(tunnel);
        CkFtp2_Dispose(ftp);
        return;
    }



    CkSshTunnel_Dispose(tunnel);
    CkFtp2_Dispose(ftp);

    }