Problem mit Portscanner

[Ascharan]

Hi Leut ich hab n Kleines Problem mit mein Portscanner .
mein portscanner soll jeden port den er scannt in eine listbox schreiben soweit sogut das functioniert ja prob: er schreibt erst nach den 5 oder 6 port was in die listbox sonst zeigt er nichts an achja ich lese exat nur 10 ports aus mehr muss er nicht können

thx im voraus

hier mein Code:

[code]
// port.cpp
#include "stdafx.h"
#include "resource.h"

#include <winsock.h>
#include <stdlib.h>
#include <commctrl.h>

#pragma comment(lib, "ws2_32.lib")
#pragma comment(lib, "comctl32.lib")

LRESULT CALLBACK	DlgProc( HWND, UINT, WPARAM, LPARAM );

void ScanForOpenPorts(PVOID pVoid);

HINSTANCE hComCtl;

char g_szIpAdress[50];

int g_iPortStart1, 
	g_iPortStart2,
	g_iPortStart3,
	g_iPortStart4,
	g_iPortStart5,
	g_iPortStart6,
	g_iPortStart7,
	g_iPortStart8,
	g_iPortStart9,
	g_iPortStart10;

int iDif;

HWND g_hWndList, g_hDlg, g_hWndStatus;

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow )
{
	hComCtl = LoadLibrary(TEXT("comctl32.dll"));
	DialogBox(hInstance, (LPCTSTR)IDD_SCANNER, NULL, (DLGPROC)DlgProc);
	return 0;
}

LRESULT CALLBACK DlgProc( HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam )
{
	char szPortStart1[10];
	char szPortStart2[10];
	char szPortStart3[10];
	char szPortStart4[10];
	char szPortStart5[10];
	char szPortStart6[10];
	char szPortStart7[10];
	char szPortStart8[10];
	char szPortStart9[10];
	char szPortStart10[10];

	static HWND hWndIP, 
				hWndSrtPrt1 , 
				hWndSrtPrt2, 
				hWndSrtPrt3, 
				hWndSrtPrt4, 
				hWndSrtPrt5, 
				hWndSrtPrt6, 
				hWndSrtPrt7, 
				hWndSrtPrt8, 
				hWndSrtPrt9, 
				hWndSrtPrt10;

	switch( message )
	{
		case WM_INITDIALOG:
			SetWindowText(GetDlgItem(hDlg, IDC_IPADDRESS),		"127.0.0.1");
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART1),		"21");//ftp
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART2),		"25");//smtp
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART3),		"80");//http
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART4),		"110");//pop3
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART5),		"143");//imap
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART6),		"443");//https
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART7),		"3306");//mysql
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART8),		"8009");//ajp
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART9),		"8080");//httpalt
			SetWindowText(GetDlgItem(hDlg, IDC_PORTSTART10),	"65535");//chat

			hWndIP		= GetDlgItem(hDlg, IDC_IPADDRESS);
			hWndSrtPrt1	= GetDlgItem(hDlg, IDC_PORTSTART1);
			hWndSrtPrt2	= GetDlgItem(hDlg, IDC_PORTSTART2);
			hWndSrtPrt3	= GetDlgItem(hDlg, IDC_PORTSTART3);
			hWndSrtPrt4	= GetDlgItem(hDlg, IDC_PORTSTART4);
			hWndSrtPrt5	= GetDlgItem(hDlg, IDC_PORTSTART5);
			hWndSrtPrt6	= GetDlgItem(hDlg, IDC_PORTSTART6);
			hWndSrtPrt7	= GetDlgItem(hDlg, IDC_PORTSTART7);
			hWndSrtPrt8	= GetDlgItem(hDlg, IDC_PORTSTART8);
			hWndSrtPrt9	= GetDlgItem(hDlg, IDC_PORTSTART9);
			hWndSrtPrt10	= GetDlgItem(hDlg, IDC_PORTSTART10);
			g_hWndList  = GetDlgItem(hDlg, IDC_OPENPORTS);
			g_hWndStatus  = GetDlgItem(hDlg, IDC_STATUS);
			g_hDlg		= hDlg;

			return TRUE;

		case WM_COMMAND:
			switch(LOWORD(wParam))
			{
				case IDOK:
					SendMessage(hWndIP, WM_GETTEXT, (WPARAM)sizeof(g_szIpAdress), (LPARAM)g_szIpAdress);
					SendMessage(hWndSrtPrt1, WM_GETTEXT, (WPARAM)sizeof(szPortStart1), (LPARAM)szPortStart1);
					SendMessage(hWndSrtPrt2, WM_GETTEXT, (WPARAM)sizeof(szPortStart2), (LPARAM)szPortStart2);
					SendMessage(hWndSrtPrt3, WM_GETTEXT, (WPARAM)sizeof(szPortStart3), (LPARAM)szPortStart3);
					SendMessage(hWndSrtPrt4, WM_GETTEXT, (WPARAM)sizeof(szPortStart4), (LPARAM)szPortStart4);
					SendMessage(hWndSrtPrt5, WM_GETTEXT, (WPARAM)sizeof(szPortStart5), (LPARAM)szPortStart5);
					SendMessage(hWndSrtPrt6, WM_GETTEXT, (WPARAM)sizeof(szPortStart6), (LPARAM)szPortStart6);
					SendMessage(hWndSrtPrt7, WM_GETTEXT, (WPARAM)sizeof(szPortStart7), (LPARAM)szPortStart7);
					SendMessage(hWndSrtPrt8, WM_GETTEXT, (WPARAM)sizeof(szPortStart8), (LPARAM)szPortStart8);
					SendMessage(hWndSrtPrt9, WM_GETTEXT, (WPARAM)sizeof(szPortStart9), (LPARAM)szPortStart9);
					SendMessage(hWndSrtPrt10, WM_GETTEXT, (WPARAM)sizeof(szPortStart10), (LPARAM)szPortStart10);

					g_iPortStart1 = atoi(szPortStart1);
					g_iPortStart2 = atoi(szPortStart2);
					g_iPortStart3 = atoi(szPortStart3);
					g_iPortStart4 = atoi(szPortStart4);
					g_iPortStart5 = atoi(szPortStart5);
					g_iPortStart6 = atoi(szPortStart6);
					g_iPortStart7 = atoi(szPortStart7);
					g_iPortStart8 = atoi(szPortStart8);
					g_iPortStart9 = atoi(szPortStart9);
					g_iPortStart10 = atoi(szPortStart10);
					ScanForOpenPorts(0);
					break;
				case IDCANCEL:
					EndDialog(hDlg, LOWORD(wParam));
					return TRUE;
			}
			break;
	}
    return FALSE;
}

void ScanForOpenPorts(PVOID pVoid)
{

	char Buffer[100];
	int contr, a,b,c,d,e,f,g,h,i,j;
	SOCKET sock = INVALID_SOCKET;
	WORD wVersionReg = MAKEWORD(1, 1); 
	WSADATA wsaData;

	iDif =  g_iPortStart1,
			g_iPortStart2,
			g_iPortStart3,
			g_iPortStart4,
			g_iPortStart5,
			g_iPortStart6,
			g_iPortStart7,
			g_iPortStart8,
			g_iPortStart9,
			g_iPortStart10;

	if (int err = WSAStartup(wVersionReg, &wsaData) != 0)
	{
		SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Winsock32.dll");
	}

	struct sockaddr_in server;   
	server.sin_addr.s_addr = inet_addr(g_szIpAdress); 
	server.sin_family = AF_INET; 

	if (a = g_iPortStart1) 
    { 

		server.sin_port = htons(a); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 
		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //FTP", a);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //FTP", a);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	} 

	if (b = g_iPortStart2) 
    { 

		server.sin_port = htons(b); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 
		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //SMTP", b);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //SMTP", b);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	}
	if (c = g_iPortStart3) 
    { 

		server.sin_port = htons(c); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 
		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //HTTP", c);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //HTTP", c);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	}
	if (d = g_iPortStart4) 
    { 

		server.sin_port = htons(c); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 
		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //POP3", d);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //POP3", d);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	}
	if (e = g_iPortStart5) 
    { 

		server.sin_port = htons(e); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 
		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //IMAP", e);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //IMAP", e);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	}
	if (f = g_iPortStart6) 
    { 

		server.sin_port = htons(f); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 
		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //HTTPS", f);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //HTTPS", f);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	}
	if (g = g_iPortStart7) 
    { 

		server.sin_port = htons(g); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 
		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //MYSQL", g);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //MYSQL", g);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	}
	if (h = g_iPortStart8) 
    { 

		server.sin_port = htons(h); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 

		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //AJP", h);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //AJP", h);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	}
	if (i = g_iPortStart9) 
    { 

		server.sin_port = htons(i); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 
		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //HTTPALT", i);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //HTTPALT", i);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	}

	if (j = g_iPortStart10) 
    { 

		server.sin_port = htons(j); 

		if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) 
		{ 
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)"-Err: Port erstellen");
		} 
		contr = connect(sock, (sockaddr *) &server ,sizeof(server)); 
		if (contr < 0)
		{ //Port Closed
			wsprintf(Buffer, "Port %d is closed //CHAT", j);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		else 
		{
			//Port Open !!!
			wsprintf(Buffer, "Port %d is open //CHAT", j);
			SendMessage(g_hWndList, LB_ADDSTRING, (WPARAM)0, (LPARAM)Buffer);
		}
		closesocket(sock); 
		SendMessage(g_hWndList, WM_VSCROLL, (WPARAM)MAKEWPARAM(SB_PAGEDOWN, 0), (LPARAM)0);

	}

  WSACleanup(); 
}
[/code]

[code]
//port.rc
//Microsoft Developer Studio generated resource script.
//
#include "resource.h"

#define APSTUDIO_READONLY_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 2 resource.
//
#include "afxres.h"

/////////////////////////////////////////////////////////////////////////////
#undef APSTUDIO_READONLY_SYMBOLS

/////////////////////////////////////////////////////////////////////////////
// Deutsch (Deutschland) resources

#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_DEU)
#ifdef _WIN32
LANGUAGE LANG_GERMAN, SUBLANG_GERMAN
#pragma code_page(1252)
#endif //_WIN32

#ifdef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// TEXTINCLUDE
//

1 TEXTINCLUDE DISCARDABLE 
BEGIN
    "resource.h\0"
END

2 TEXTINCLUDE DISCARDABLE 
BEGIN
    "#include ""afxres.h""\r\n"
    "\0"
END

3 TEXTINCLUDE DISCARDABLE 
BEGIN
    "\r\n"
    "\0"
END

#endif    // APSTUDIO_INVOKED

/////////////////////////////////////////////////////////////////////////////
//
// Icon
//

// Icon with lowest ID value placed first to ensure application icon
// remains consistent on all systems.
IDI_MAINFRAME           ICON    DISCARDABLE     "Res\\Icons\\port.ico"
IDI_SCAN                ICON    DISCARDABLE     "Res\\Icons\\connected.ico"

/////////////////////////////////////////////////////////////////////////////
//
// Dialog
//

IDD_SCANNER DIALOGEX 0, 0, 223, 252
STYLE DS_MODALFRAME | DS_CENTER | WS_POPUP | WS_CAPTION | WS_SYSMENU
EXSTYLE WS_EX_TOOLWINDOW
CAPTION "  Port Scanner"
FONT 8, "MS Sans Serif"
BEGIN
    DEFPUSHBUTTON   "Scan Ports",IDOK,111,231,50,14
    PUSHBUTTON      "Beenden",IDCANCEL,166,231,50,14
    LISTBOX         IDC_OPENPORTS,19,170,183,41,LBS_NOINTEGRALHEIGHT | 
                    WS_VSCROLL | WS_TABSTOP
    EDITTEXT        IDC_PORTSTART1,50,68,40,12,ES_AUTOHSCROLL
    CONTROL         "IPAddress1",IDC_IPADDRESS,"SysIPAddress32",WS_TABSTOP,
                    101,20,100,12
    LTEXT           "IP Adresse : ",IDC_STATIC,53,20,39,12,SS_CENTERIMAGE
    ICON            IDI_SCAN,IDC_STATIC,14,14,21,20,SS_REALSIZEIMAGE,
                    WS_EX_DLGMODALFRAME
    EDITTEXT        IDC_PORTSTART2,50,82,40,12,ES_AUTOHSCROLL
    EDITTEXT        IDC_PORTSTART3,50,97,40,12,ES_AUTOHSCROLL
    EDITTEXT        IDC_PORTSTART4,50,111,40,12,ES_AUTOHSCROLL
    EDITTEXT        IDC_PORTSTART5,50,126,40,12,ES_AUTOHSCROLL
    EDITTEXT        IDC_PORTSTART6,133,68,40,12,ES_AUTOHSCROLL
    EDITTEXT        IDC_PORTSTART7,133,82,40,12,ES_AUTOHSCROLL
    EDITTEXT        IDC_PORTSTART8,133,97,40,12,ES_AUTOHSCROLL
    EDITTEXT        IDC_PORTSTART9,133,111,40,12,ES_AUTOHSCROLL
    EDITTEXT        IDC_PORTSTART10,133,126,40,12,ES_AUTOHSCROLL
    GROUPBOX        "",IDC_STATIC,7,7,209,37,BS_CENTER
    GROUPBOX        "Ports : ",IDC_STATIC,7,50,209,102,BS_CENTER
    GROUPBOX        "Status",IDC_STATIC,7,157,209,65,BS_CENTER
END

/////////////////////////////////////////////////////////////////////////////
//
// DESIGNINFO
//

#ifdef APSTUDIO_INVOKED
GUIDELINES DESIGNINFO DISCARDABLE 
BEGIN
    IDD_SCANNER, DIALOG
    BEGIN
        LEFTMARGIN, 7
        RIGHTMARGIN, 216
        TOPMARGIN, 7
        BOTTOMMARGIN, 245
    END
END
#endif    // APSTUDIO_INVOKED

/////////////////////////////////////////////////////////////////////////////
//
// 24
//

1                       24      DISCARDABLE     "Res\\Style\\xpstyle.xml"
#endif    // Deutsch (Deutschland) resources
/////////////////////////////////////////////////////////////////////////////

#ifndef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 3 resource.
//

/////////////////////////////////////////////////////////////////////////////
#endif    // not APSTUDIO_INVOKED

[/code]

[Jochen Kalmbach]

Wenn Du nach einem LB_ADDSTRING nicht die Msg-Loop durchläufst, wird dies nicht gezeichnet...
Deshalb musst Du die Msg-Loop einige Mal durchlaufen, bis Du wieder weitermachst... oder Du verlagerst Dein "Scanner" in einen anderen Thread als den UI-Thread.
PS: Port-"Scanner" arbeiten nicht mit "connect"...

[Ascharan]

Mit was dann auser connect
bsp.:Raw

[Jochen Kalmbach]

Jau... mit RAW sockets und dem senden von SYN-Paketen... dazu kannst Du ja mal die RFC zu TCP/IP lesen...
http://www.faqs.org/rfcs/rfc793.html

Beispiele (nicht verifiziert):
http://www.codeproject.com/internet/NagTPortScanner.asp
http://www.codeproject.com/internet/tcpscan.asp

[Ascharan]

Hab bei den Beispielen n Kleines Problem Codeprojekt programmiert überwiegend mit mfc das ich aber nicht kann bsp nicht benutze.
andere ideen

Aber dank für die Schnelle Antwort