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(Unicode C) TCP Socket through SSH Tunnel (Port Forwarding)Demonstrates using Chilkat Socket to communicate to a TCP service through an SSH tunnel. This example will connect to an NIST time server and (using the old Time Protocol (RFC 868)), will read the current GMT time. Note: This is not necessarily a recommended means for getting the current date/time. The most commonly used time protocol is the Network Time Protocol (RFC-1305). The intent of this example is to show how TCP communications can occur through an SSH tunnel.
#include <C_CkSocketW.h> #include <C_CkDateTimeW.h> void ChilkatSample(void) { HCkSocketW tunnel; const wchar_t *sshHostname; int sshPort; BOOL success; HCkSocketW channel; int maxWaitMs; BOOL useTls; BOOL bigEndian; HCkDateTimeW dt; BOOL bLocalTime; // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. tunnel = CkSocketW_Create(); sshHostname = L"sftp.example.com"; sshPort = 22; // Connect to an SSH server and establish the SSH tunnel: success = CkSocketW_SshOpenTunnel(tunnel,sshHostname,sshPort); if (success != TRUE) { wprintf(L"%s\n",CkSocketW_lastErrorText(tunnel)); CkSocketW_Dispose(tunnel); return; } // Authenticate with the SSH server via a login/password // or with a public key. // This example demonstrates SSH password authentication. success = CkSocketW_SshAuthenticatePw(tunnel,L"mySshLogin",L"mySshPassword"); if (success != TRUE) { wprintf(L"%s\n",CkSocketW_lastErrorText(tunnel)); CkSocketW_Dispose(tunnel); return; } // OK, the SSH 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 maxWaitMs = 4000; useTls = FALSE; channel = CkSocketW_SshOpenChannel(tunnel,L"time-c.nist.gov",37,useTls,maxWaitMs); if (CkSocketW_getLastMethodSuccess(tunnel) == FALSE) { wprintf(L"%s\n",CkSocketW_lastErrorText(tunnel)); CkSocketW_Dispose(tunnel); 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 = CkSocketW_ReceiveInt32(channel,bigEndian); if (success != TRUE) { wprintf(L"%s\n",CkSocketW_lastErrorText(channel)); CkSocketW_Dispose(channel); CkSocketW_Dispose(tunnel); return; } dt = CkDateTimeW_Create(); CkDateTimeW_SetFromNtpTime(dt,CkSocketW_getReceivedInt(channel)); // Show the current local date/time bLocalTime = TRUE; wprintf(L"Current local date/time: %s\n",CkDateTimeW_getAsRfc822(dt,bLocalTime)); // Close the SSH channel. success = CkSocketW_Close(channel,maxWaitMs); if (success != TRUE) { wprintf(L"%s\n",CkSocketW_lastErrorText(channel)); CkSocketW_Dispose(channel); CkSocketW_Dispose(tunnel); CkDateTimeW_Dispose(dt); return; } CkSocketW_Dispose(channel); // It is possible to create a new channel from the existing SSH tunnel for the next connection: // Any number of channels may be created from the same SSH tunnel. // Multiple channels may coexist at the same time. channel = CkSocketW_SshOpenChannel(tunnel,L"time-a.nist.gov",37,useTls,maxWaitMs); if (CkSocketW_getLastMethodSuccess(tunnel) == FALSE) { wprintf(L"%s\n",CkSocketW_lastErrorText(tunnel)); CkSocketW_Dispose(tunnel); CkDateTimeW_Dispose(dt); return; } // Review the LastErrorText to see that the connection was made via the SSH tunnel: wprintf(L"%s\n",CkSocketW_lastErrorText(tunnel)); // Close the connection to time-a.nist.gov. This is actually closing our channel // within the SSH tunnel, but keeps the tunnel open for the next port-forwarded connection. success = CkSocketW_Close(channel,maxWaitMs); if (success != TRUE) { wprintf(L"%s\n",CkSocketW_lastErrorText(channel)); CkSocketW_Dispose(channel); CkSocketW_Dispose(tunnel); CkDateTimeW_Dispose(dt); return; } CkSocketW_Dispose(channel); // Finally, close the SSH tunnel. success = CkSocketW_SshCloseTunnel(tunnel); if (success != TRUE) { wprintf(L"%s\n",CkSocketW_lastErrorText(tunnel)); CkSocketW_Dispose(tunnel); CkDateTimeW_Dispose(dt); return; } wprintf(L"TCP SSH tunneling example completed.\n"); CkSocketW_Dispose(tunnel); CkDateTimeW_Dispose(dt); } |
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