C

SSH Tunnel Inside another SSH Tunnel

See more SSH Tunnel Examples

Demonstrates how to create a TCP/IP socket connection through an SSH tunnel that is dynamic port forwarded through another SSH tunnel. C

#include <C_CkSshTunnel.h>
#include <C_CkSocket.h>
#include <C_CkDateTime.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSshTunnel tunnel;
    const char *sshHostname;
    int sshPort;
    HCkSocket tunnelB;
    HCkSocket channel;
    int maxWaitMs;
    BOOL useTls;
    BOOL bigEndian;
    HCkDateTime dt;
    BOOL bLocalTime;
    BOOL waitForThreadExit;

    success = FALSE;

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

    tunnel = CkSshTunnel_Create();

    sshHostname = "www.ssh-serverA.com";
    sshPort = 22;

    // Connect to an SSH server and establish the SSH tunnel:
    success = CkSshTunnel_Connect(tunnel,sshHostname,sshPort);
    if (success == FALSE) {
        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 == FALSE) {
        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 == FALSE) {
        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, Socket, 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.

    tunnelB = CkSocket_Create();

    // Indicate that the socket object is to use our portable SOCKS proxy/SSH tunnel running in our background thread.
    CkSocket_putSocksHostname(tunnelB,"localhost");
    CkSocket_putSocksPort(tunnelB,1080);
    CkSocket_putSocksVersion(tunnelB,5);
    CkSocket_putSocksUsername(tunnelB,"chilkat123");
    CkSocket_putSocksPassword(tunnelB,"password123");

    // Open a new SSH tunnel through the existing tunnel (via what we treat as a SOCKS5 proxy,
    // but it is actually a dynamic port-forwarded SSH tunnel).
    success = CkSocket_SshOpenTunnel(tunnelB,"www.ssh-serverB.com",22);
    if (success == FALSE) {
        printf("%s\n",CkSocket_lastErrorText(tunnelB));
        CkSshTunnel_Dispose(tunnel);
        CkSocket_Dispose(tunnelB);
        return;
    }

    // Authenticate with ssh-serverB.com
    success = CkSocket_SshAuthenticatePw(tunnelB,"uname","pwd");
    if (success == FALSE) {
        printf("%s\n",CkSocket_lastErrorText(tunnelB));
        CkSshTunnel_Dispose(tunnel);
        CkSocket_Dispose(tunnelB);
        return;
    }

    // OK, the SSH tunnel (within a tunnel) is setup.  Now open a channel within the tunnel.
    // Once the channel is obtained, the Socket API may
    // be used exactly the same as usual, except all communications
    // are sent through the channel in the SSH tunnel.
    // Any number of channels may be created from the same SSH tunnel.
    // Multiple channels may coexist at the same time.

    // Connect to an NIST time server and read the current date/time
    channel = CkSocket_Create();
    maxWaitMs = 4000;
    useTls = FALSE;
    success = CkSocket_SshNewChannel(tunnelB,"time-c.nist.gov",37,useTls,maxWaitMs,channel);
    if (success == FALSE) {
        printf("%s\n",CkSocket_lastErrorText(tunnelB));
        CkSshTunnel_Dispose(tunnel);
        CkSocket_Dispose(tunnelB);
        CkSocket_Dispose(channel);
        return;
    }

    // The time server will send a big-endian 32-bit integer representing
    // the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
    // The ReceiveInt32 method will receive a 4-byte integer, but returns
    // TRUE or FALSE to indicate success.  If successful, the integer
    // is obtained via the ReceivedInt property.
    bigEndian = TRUE;
    success = CkSocket_ReceiveInt32(channel,bigEndian);
    if (success == FALSE) {
        printf("%s\n",CkSocket_lastErrorText(channel));
        CkSshTunnel_Dispose(tunnel);
        CkSocket_Dispose(tunnelB);
        CkSocket_Dispose(channel);
        return;
    }

    dt = CkDateTime_Create();
    CkDateTime_SetFromNtpTime(dt,CkSocket_getReceivedInt(channel));

    // Show the current local date/time
    bLocalTime = TRUE;
    printf("Current local date/time: %s\n",CkDateTime_getAsRfc822(dt,bLocalTime));

    // Close the SSH channel.
    success = CkSocket_Close(channel,maxWaitMs);
    if (success == FALSE) {
        printf("%s\n",CkSocket_lastErrorText(channel));
        CkSshTunnel_Dispose(tunnel);
        CkSocket_Dispose(tunnelB);
        CkSocket_Dispose(channel);
        CkDateTime_Dispose(dt);
        return;
    }

    // Stop the background listen/accept thread:
    waitForThreadExit = TRUE;
    success = CkSshTunnel_StopAccepting(tunnel,waitForThreadExit);
    if (success == FALSE) {
        printf("%s\n",CkSshTunnel_lastErrorText(tunnel));
        CkSshTunnel_Dispose(tunnel);
        CkSocket_Dispose(tunnelB);
        CkSocket_Dispose(channel);
        CkDateTime_Dispose(dt);
        return;
    }

    // Close the SSH tunnel (would also kick any remaining connected clients).
    success = CkSshTunnel_CloseTunnel(tunnel,waitForThreadExit);
    if (success == FALSE) {
        printf("%s\n",CkSshTunnel_lastErrorText(tunnel));
        CkSshTunnel_Dispose(tunnel);
        CkSocket_Dispose(tunnelB);
        CkSocket_Dispose(channel);
        CkDateTime_Dispose(dt);
        return;
    }



    CkSshTunnel_Dispose(tunnel);
    CkSocket_Dispose(tunnelB);
    CkSocket_Dispose(channel);
    CkDateTime_Dispose(dt);

    }