Request SSH X11 Forwarding

See more SSH Examples

Demonstrates the Chilkat Ssh.SendReqX11Forwarding method, which sends an X11-forwarding request on a session channel. The arguments are the channel number, whether forwarding is limited to a single connection, and the X11 authentication protocol, cookie, and screen number.

Background: X11 forwarding lets a graphical program running on the remote host display its window on your local machine, tunneled over SSH. This is a low-level method that only sends the protocol request — your application is still responsible for the local X server side of the arrangement. The authentication cookie guards the forwarded display, so it should be a freshly generated value rather than a fixed constant.

Chilkat C Downloads

Download Chilkat for C

#include <C_CkSsh.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSsh ssh;
    int sshPort;
    const char *password;
    int channelNum;
    BOOL singleConnection;
    const char *authProt;
    const char *authCookie;
    int screenNum;

    success = FALSE;

    //  Demonstrates the Ssh.SendReqX11Forwarding method, which sends an SSH X11-forwarding request
    //  on a session channel.  The 1st argument is the channel number, the 2nd limits forwarding to a
    //  single connection, and the 3rd through 5th supply the X11 authentication protocol, cookie,
    //  and screen number.

    ssh = CkSsh_Create();

    sshPort = 22;
    success = CkSsh_Connect(ssh,"ssh.example.com",sshPort);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    //  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.
    password = "mySshPassword";

    success = CkSsh_AuthenticatePw(ssh,"mySshLogin",password);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    //  Open a session channel.  A negative return value indicates failure.
    channelNum = CkSsh_OpenSessionChannel(ssh);
    if (channelNum < 0) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    //  Request X11 forwarding.  Named variables make each argument's meaning clear.
    singleConnection = FALSE;
    authProt = "MIT-MAGIC-COOKIE-1";
    authCookie = "d92f5e1a7c8b4306af17c2e5b9d43081";
    screenNum = 0;
    success = CkSsh_SendReqX11Forwarding(ssh,channelNum,singleConnection,authProt,authCookie,screenNum);
    if (success == FALSE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        return;
    }

    printf("X11 forwarding requested.\n");

    CkSsh_Disconnect(ssh);


    CkSsh_Dispose(ssh);

    }