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(DataFlex) 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. Note: This example requires Chilkat v11.0.0 or greater.
Use ChilkatAx-win32.pkg Procedure Test Boolean iSuccess Handle hoTunnel String sSshHostname Integer iSshPort Integer iMaxWaitMs Boolean iUseTls Variant vChannel Handle hoChannel Boolean iBigEndian Handle hoDt Boolean iBLocalTime String sTemp1 Integer iTemp1 Move False To iSuccess // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. Get Create (RefClass(cComChilkatSocket)) To hoTunnel If (Not(IsComObjectCreated(hoTunnel))) Begin Send CreateComObject of hoTunnel End Move "sftp.example.com" To sSshHostname Move 22 To iSshPort // Connect to an SSH server and establish the SSH tunnel: Get ComSshOpenTunnel Of hoTunnel sSshHostname iSshPort To iSuccess If (iSuccess = False) Begin Get ComLastErrorText Of hoTunnel To sTemp1 Showln sTemp1 Procedure_Return End // Authenticate with the SSH server via a login/password // or with a public key. // This example demonstrates SSH password authentication. Get ComSshAuthenticatePw Of hoTunnel "mySshLogin" "mySshPassword" To iSuccess If (iSuccess = False) Begin Get ComLastErrorText Of hoTunnel To sTemp1 Showln sTemp1 Procedure_Return End // 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 Move 4000 To iMaxWaitMs Move False To iUseTls Get Create (RefClass(cComChilkatSocket)) To hoChannel If (Not(IsComObjectCreated(hoChannel))) Begin Send CreateComObject of hoChannel End Get pvComObject of hoChannel to vChannel Get ComSshNewChannel Of hoTunnel "time-c.nist.gov" 37 iUseTls iMaxWaitMs vChannel To iSuccess If (iSuccess = False) Begin Get ComLastErrorText Of hoTunnel To sTemp1 Showln sTemp1 Procedure_Return End // 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. Move True To iBigEndian Get ComReceiveInt32 Of hoChannel iBigEndian To iSuccess If (iSuccess = False) Begin Get ComLastErrorText Of hoChannel To sTemp1 Showln sTemp1 Procedure_Return End Get Create (RefClass(cComCkDateTime)) To hoDt If (Not(IsComObjectCreated(hoDt))) Begin Send CreateComObject of hoDt End Get ComReceivedInt Of hoChannel To iTemp1 Get ComSetFromNtpTime Of hoDt iTemp1 To iSuccess // Show the current local date/time Move True To iBLocalTime Get ComGetAsRfc822 Of hoDt iBLocalTime To sTemp1 Showln "Current local date/time: " sTemp1 // Close the SSH channel. Get ComClose Of hoChannel iMaxWaitMs To iSuccess If (iSuccess <> True) Begin Get ComLastErrorText Of hoChannel To sTemp1 Showln sTemp1 Procedure_Return End // 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. Get pvComObject of hoChannel to vChannel Get ComSshNewChannel Of hoTunnel "time-a.nist.gov" 37 iUseTls iMaxWaitMs vChannel To iSuccess If (iSuccess = False) Begin Get ComLastErrorText Of hoTunnel To sTemp1 Showln sTemp1 Procedure_Return End // Review the LastErrorText to see that the connection was made via the SSH tunnel: Get ComLastErrorText Of hoTunnel To sTemp1 Showln sTemp1 // 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. Get ComClose Of hoChannel iMaxWaitMs To iSuccess If (iSuccess <> True) Begin Get ComLastErrorText Of hoChannel To sTemp1 Showln sTemp1 Procedure_Return End // Finally, close the SSH tunnel. Get ComSshCloseTunnel Of hoTunnel To iSuccess If (iSuccess = False) Begin Get ComLastErrorText Of hoTunnel To sTemp1 Showln sTemp1 Procedure_Return End Showln "TCP SSH tunneling example completed." End_Procedure |
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