private static extern uint RasEnumConnections(

        uint ret = RasEnumConnections(tempConn, ref lpcb, out lpcConnections);

        ret = RasEnumConnections(allConnections, ref lpcb, out lpcConnections);

    internal static extern UInt32 RasEnumConnections([In, Out] _RASCONN[] lprasconn, ref UInt32 lpcb, ref UInt32 lpcConnections);

        if (RasEnumConnections(rasconn, ref size, ref noelements) != 0x00)

            if (RasEnumConnections(rasconn, ref size, ref noelements) != 0x00) { rasconn = null; }

Use this function together with RasEnumConnections, to return a list of the active connections, then the sample code below will loop through the RASCONN[] array and close each one.

public static extern int RasEnumConnections(

int nRet = RAW.RasEnumConnections(connections, ref cb, out connectionsCount);

nRet = RAW.RasEnumConnections(connections, ref cb, out connectionsCount);

if (RAW.RasEnumConnections(null, ref cb, out connectionCount) == RAW.ERROR_BUFFER_TOO_SMALL)

    if (RasApi.RasEnumConnections(buffer, ref cb, out conns) == RAW.ERROR_SUCCESS)