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I guess you'll need to use sockets and communicate according to the PPTP protocol. <br />
For a tutorial on sockets, see: <a href="http://www.codeproject.com/KB/IP/winsockintro02.aspx" rel="ugc">http://www.codeproject.com/KB/IP/winsockintro02.aspx</a><br />
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Here's an open-source implementation of PPTP:<br />
<a href="http://pptpclient.sourceforge.net/" rel="ugc">http://pptpclient.sourceforge.net/</a>
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I guess you'll need to use sockets and communicate according to the PPTP protocol.
For a tutorial on sockets, see: http://www.codeproject.com/KB/IP/winsockintro02.aspx [http://www.codeproject.com/KB/IP/winsockintro02.aspx]

Here's an open-source implementation of PPTP:
http://pptpclient.sourceforge.net/ [http://pptpclient.sourceforge.net/]

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The client is Microsoft Windows XP. &nbsp;I already have a PPTP connection set up in the OS. &nbsp;Is there a way to call that?
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The client is Microsoft Windows XP.  I already have a PPTP connection set up in the OS.  Is there a way to call that?

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I think you can do that with TAPI, because Windows sees a PPTP connection as a regular dial-up connection. See:<br />
<a href="http://www.codeproject.com/KB/IP/TAPISample.aspx" rel="ugc">http://www.codeproject.com/KB/IP/TAPISample.aspx</a>
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I think you can do that with TAPI, because Windows sees a PPTP connection as a regular dial-up connection. See:
http://www.codeproject.com/KB/IP/TAPISample.aspx [http://www.codeproject.com/KB/IP/TAPISample.aspx]

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I have a working PPTP VPN server. &nbsp;How can I use C++ to initiate the connection from the client? (I want to write code to &quot;dial up&quot; the VPN server. &nbsp;The code will run from the client.)
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I have a working PPTP VPN server.  How can I use C++ to initiate the connection from the client? (I want to write code to "dial up" the VPN server.  The code will run from the client.)

C++ to connect to PPTP VPN?

C++ is an intermediate-level general-purpose programming language, not to be confused with C or C#. It was developed as a set of extensions to the C programming language to improve type-safety and add support for automatic resource management, object-orientation, generic programming, and exception handling, among other features.

C is a general-purpose, imperative computer programming language, supporting structured programming, lexical variable scope and recursion, while a static type system prevents many unintended operations. By design, C provides constructs that map efficiently to typical machine instructions, so it has found lasting use in applications that had formerly been coded in assembly language, including operating systems as well as various application software for computers ranging from supercomputers to embedded systems. It is distinct from C++ (which has its roots in C) and C#, and many later languages have borrowed directly or indirectly from C.