< Phonebook & User Credentials | RAS Main | Chap 13: IP Helper Functions >
Remote Access Service (RAS) 12 Part 3
What do we have in this chapter 12 part 3?
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Virtual Private Network (VPN)
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RAS Program Example
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Useful References
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Virtual Private Network (VPN)
As we mentioned previously, RAS can also be used to form secure VPN connections over an IP network. You can do this as long as you have IP connectivity established on your computer either through RAS or through a network adapter. Today some computers have IP connectivity established either through Digital Subscriber Line (DSL) or cable modems and do not use RAS serial devices to connect to the Internet. If you do not have IP connectivity established, you can use RasDial() first to establish IP connectivity over a serial device, as we have already described. Once IP connectivity is established either through RAS or through a network adapter, you can use RasDial() to establish a secure link to your remote network over the existing IP connection. Using the RAS client to establish a VPN connection requires building a phonebook entry that contains the remote VPN server's IP address information on the remote network instead of telephone dialing information. In a phonebook RASENTRY structure you must set the szDeviceType field to the string “RASDT_Vpn”. Once this field is set, the szLocalPhoneNumber field can be used to specify either a DNS name or an IP address string of the remote VPN server instead of a phone number. After the phonebook entry is established, RasDial() can be called using the phonebook entry to establish the VPN link.
RAS Program Example
Create an empty Win32 console mode application project and give the project name.
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Add the following code.
// Description:
//
// This sample demonstrates how to develop a RAS application that is
// capable of forming RAS connections to a remote server by using the
// RasDial API. The sample uses RasDial in the asynchronous operating
// mode which is the preferred mode of establishing RAS connections
// because you can monitor connection activities as they occur in the
// RasDial API.
//
// Command line options:
// RASDialExample -e [entry name] -p [phone number] -u [username] -z [password] -d [domain]
//
#define WIN32_LEAN_AND_MEAN
#include <stdio.h>
#include <windows.h>
// Link to rasapi32.lib
#include <ras.h>
#include <raserror.h>
#include <string.h>
#include <winbase.h>
#include <time.h>
#include <stdlib.h>
void WINAPI RasDialFunc(UINT unMsg, RASCONNSTATE rasconnstate, DWORD dwError);
HANDLE gTerminalEvent;
// Usage
void Usage(char *progname)
{
fprintf(stderr, "Usage:\n%s \t-e [entry name] -p [phone number] "
"\n\t\t-u [username] -z [password] -d [domain]\n", progname);
exit(0);
}
void main(int argc, char*argv[])
{
RASDIALPARAMS RasDialParams;
RASCONNSTATUS RasConnStatus;
HRASCONN hRasConn;
DWORD Ret;
DWORD tcLast;
INT i;
// Create the event that indicates a terminal state
if ((gTerminalEvent = CreateEvent(NULL, FALSE, FALSE, NULL)) == NULL)
{
printf("CreateEvent() failed with error code %d\n", GetLastError());
return;
}
else
printf("CreateEvent() is OK!\n");
RasDialParams.dwSize = sizeof(RASDIALPARAMS);
lstrcpy(RasDialParams.szEntryName, L"");
lstrcpy(RasDialParams.szPhoneNumber, L"");
lstrcpy(RasDialParams.szUserName, L"");
lstrcpy(RasDialParams.szPassword, L"");
lstrcpy(RasDialParams.szDomain, L"");
// Copy command line arguments into the RASDIALPARAMS structure
if (argc >1)
{
for(i=1;i <argc;i++)
{
if ((argv[i][0] == '-') || (argv[i][0] == '/'))
{
switch(tolower(argv[i][1]))
{
case 'e': // Entry name
lstrcpy(RasDialParams.szEntryName, (LPCWSTR)argv[++i]);
break;
case 'p': // Phone number
lstrcpy(RasDialParams.szPhoneNumber, (LPCWSTR)argv[++i]);
break;
case 'u': // User name
lstrcpy(RasDialParams.szUserName, (LPCWSTR)argv[++i]);
break;
case 'z': // Password
lstrcpy(RasDialParams.szPassword, (LPCWSTR)argv[++i]);
break;
case 'd': // Domain name
lstrcpy(RasDialParams.szDomain, (LPCWSTR)argv[++i]);
break;
default:
Usage(argv[0]);
break;
}
}
else
Usage(argv[0]);
}
}
else
Usage(argv[0]);
// Dial out asynchronously using RasDial()
printf("Dialing... %s\n", RasDialParams.szPhoneNumber);
hRasConn = NULL;
if (Ret = RasDial(NULL, NULL, &RasDialParams, 0, &RasDialFunc, &hRasConn))
{
// http://msdn.microsoft.com/en-us/library/bb530704(VS.85).aspx
printf("RasDial() failed with error code %d\n", Ret);
return;
}
else
printf("RasDial() is OK!\n");
// Wait for RasDial to complete or enter a paused state
Ret = WaitForSingleObject(gTerminalEvent, 50000);
switch(Ret)
{
case WAIT_TIMEOUT:
// RasDial timed out
printf("RasDial() Timed out...\n");
case WAIT_OBJECT_0:
// Normal completion or Ras Error encountered
printf("Will hang up in 5 seconds...\n");
Sleep(5000);
printf("Calling RasHangUp()...\n");
if (Ret = RasHangUp(hRasConn))
{
printf("RasHangUp() failed with error %d\n", Ret);
return;
}
RasConnStatus.dwSize = sizeof(RASCONNSTATUS);
tcLast = GetTickCount() + 10000;
while((RasGetConnectStatus(hRasConn, &RasConnStatus) != ERROR_INVALID_HANDLE) && (tcLast > GetTickCount()))
{
Sleep(50);
}
printf("Connection to %s terminated...\n", RasDialParams.szPhoneNumber);
break;
}
}
// Callback function RasDialFunc()
void WINAPI RasDialFunc(UINT unMsg, RASCONNSTATE rasconnstate, DWORD dwError)
{
char szRasString[256]; // Buffer for storing the error string
if (dwError) // Error occurred
{
RasGetErrorString((UINT)dwError, (LPWSTR)szRasString, 256);
printf("Error: %d - %S\n",dwError, szRasString);
SetEvent(gTerminalEvent);
return;
}
// Map each of the states of RasDial() and display on the screen
// the next state that RasDial() is entering
switch (rasconnstate)
{
// Running States
case RASCS_OpenPort:
printf ("Opening port...\n");
break;
case RASCS_PortOpened:
printf ("Port opened...\n");
break;
case RASCS_ConnectDevice:
printf ("Connecting device...\n");
break;
case RASCS_DeviceConnected:
printf ("Device connected...\n");
break;
case RASCS_AllDevicesConnected:
printf ("All devices connected...\n");
break;
case RASCS_Authenticate:
printf ("Authenticating...\n");
break;
case RASCS_AuthNotify:
printf ("Authentication notify...\n");
break;
case RASCS_AuthRetry:
printf ("Retrying authentication...\n");
break;
case RASCS_AuthCallback:
printf ("Authentication callback...\n");
break;
case RASCS_AuthChangePassword:
printf ("Change password...\n");
break;
case RASCS_AuthProject:
printf ("Projection phase started...\n");
break;
case RASCS_AuthLinkSpeed:
printf ("Negotiating speed...\n");
break;
case RASCS_AuthAck:
printf ("Authentication acknowledge...\n");
break;
case RASCS_ReAuthenticate:
printf ("Retrying Authentication...\n");
break;
case RASCS_Authenticated:
printf ("Authentication complete...\n");
break;
case RASCS_PrepareForCallback:
printf ("Preparing for callback...\n");
break;
case RASCS_WaitForModemReset:
printf ("Waiting for modem reset...\n");
break;
case RASCS_WaitForCallback:
printf ("Waiting for callback...\n");
break;
case RASCS_Projected:
printf ("Projection completed...\n");
break;
// http://msdn.microsoft.com/en-us/library/aa383745(VS.85).aspx
#if (WINVER >= 0x400)
case RASCS_StartAuthentication:
printf ("Starting authentication...\n");
break;
case RASCS_CallbackComplete:
printf ("Callback complete...\n");
break;
case RASCS_LogonNetwork:
printf ("Logon to the network...\n");
break;
#endif
case RASCS_SubEntryConnected:
printf ("Subentry connected...\n");
break;
case RASCS_SubEntryDisconnected:
printf ("Subentry disconnected...\n");
break;
// The RAS Paused States will not occur because
// we did not use the RASDIALEXTENSIONS structure
// to set the RDEOPT_PausedState option flag.
// The Paused States are:
// RASCS_RetryAuthentication:
// RASCS_CallbackSetByCaller:
// RASCS_PasswordExpired:
// Terminal States
case RASCS_Connected:
printf ("Connection completed.\n");
SetEvent(gTerminalEvent);
break;
case RASCS_Disconnected:
printf ("Disconnecting...\n");
SetEvent(gTerminalEvent);
break;
default:
printf ("Unknown Status = %d\n", rasconnstate);
break;
}
}
Build and run the project.
Useful References
< Phonebook & User Credentials | RAS Main | Chap 13: IP Helper Functions >