Tech Note: Automatic SLIP or PPP and HTTP restart under Windows NT

• The Remote Access service will redial automatically but, if you are using SLIP, won't login without waiting for me to press a Done button. Answer: use the RASDIAL command line program.
• The RASDIAL program doesn't redial when the line drops. Answer: write a batch file which checks the connection every so often and redials if it is down.
• Couldn't find a way to check the connection from a batch file, e.g. Ping hangs up if RAS is up but the connection is down. Answer: write a simple program called RASUP which does this.
• Even if the connection is re-established, the EMWACS HTTPS server doesn't start responding again. This causes a problem even if you are using the auto-redial feature of PPP under RAS. Answer: use the net command to stop and restart the service.

Here's how it works. I leave this batch file running in a command prompt window. Every 60 seconds it checks to see if my RAS connection is active. If there is no connection, it redials and then restarts the HTTP server.

NETCHECK.BAT

:top
rasup
if errorlevel 1 goto done
rasdial TIAC
net stop "Http server"
sleep 5
net start "Http server"
:done
sleep 60
goto top

• TIAC is the name of my login script.
• I found the sleep program with the posix utilities in the NT 3.5 resource kit (available from Microsoft's FTP site).
• I had to insert a short pause between stopping and starting the HTTP service

Here's the source to the rasup program I wrote. I'm a rusty coder, don't be harsh! The RAS.H include file comes with the Win32 SDK from Microsoft.

/* rasup.c
   Command line utility to see if any Remote Access Service
   connections are active. 
   Exit status=1 if any are active, otherwise 0.
*/
#include <windows.h>
#include <stdio.h>
#include <ras.h>

VOID main()
{
    RASCONN rasconnbuf;
    DWORD   cb = sizeof(RASCONN);
    DWORD   ret;
    DWORD   numConn;

    /*
    Required to provide buffer size
    */
    rasconnbuf.dwSize = sizeof(rasconnbuf);

    /*
    Retrieve info about first active connection (I only have one - change this if you have more)
    */
    ret = RasEnumConnections(&rasconnbuf,&cb, &numConn);

    if ((numConn == 0) | ret) {
	printf("No connection, status 0");
	exit(0);
	}
    else {
	printf("Active connection, status 1");
	exit(1);
	}
}

P.S. A thank-you to Robert Reconnu, webmaster@postapage.com, for giving me the net command syntax (I previously used the SC utility from MS VC++), and for verifying that this technique works with a PPP.