扫描开放端口

Question

我发明的东西最初是网络浏览器，但现在是开放端口的扫描器。我想知道您认为这是一个现实的或不可靠的端口测试工具。我在我的电脑上找到了一些打开的端口，并且能够通过它们发送数据。

#include <windows.h>
#include <winsock2.h>
#include <conio.h>
#include <stdio.h>
#include <iostream>
using namespace std;
#define SCK_VERSION2 0x0202
#define DEFAULT_BUFLEN 2000
#define DEFAULT_PORT 27015

namespace Globals{
     u_short PORT;
     int i = 135;
}
using namespace Globals;

int sck() {
    //----------------------
    // Declare and initialize variables.
    WSADATA wsaData;
    int iResult;

    SOCKET ConnectSocket = INVALID_SOCKET;
    struct sockaddr_in clientService;

    char name[500] = "";
    char ipADDRESS[500] = "";
    char sPORT[500] = "";

    sockaddr_in sName;
    int sNameSize =  sizeof(sName);

    char const* sendbuf = "GET  HTTP/1.1\r\n"
    "Host: 97-80-226-196.dhcp.leds.al.charter.com\r\n"
    "User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5 (.NET CLR 3.5.30729)\r\n"
    "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n"
    "Accept-Language: en-us,en;q=0.5\r\n"
    "Accept-Encoding: gzip,deflate\r\n"
    "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7\r\n"
    "Keep-Alive: 300\r\n"
    "Connection: keep-alive\r\n"
    "Pragma: no-cache\r\n"
    "DNT: 1"
    "Cache-Control: no-cache\r\n\r\n";
    char recvbuf[DEFAULT_BUFLEN];
    int recvbuflen = DEFAULT_BUFLEN;                                    //23.214.132.132 GoDaddy.com
    int WSAERROR = WSAGetLastError();                                   
    //----------------------
    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
    if (iResult != NO_ERROR) {
      printf("WSAStartup failed: %d\n", iResult);
      return 1;
    }

    //----------------------
    // Create a SOCKET for connecting to server
    ConnectSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (ConnectSocket == INVALID_SOCKET) {
        printf("Error at socket(): %i\n", WSAGetLastError() );
        WSACleanup();
        return 1;
    }

    //----------------------
    // The sockaddr_in structure specifies the address family,
    // IP address, and port of the server to be connected to.

    //u_short PORT;
    clientService.sin_family = AF_INET;
    clientService.sin_addr.s_addr = inet_addr(//The ip address);                            
    clientService.sin_port = htons(PORT);

    //----------------------
    // Connect to server.
    iResult = connect( ConnectSocket, (SOCKADDR*) &clientService, sizeof(clientService) );
    if ( iResult == SOCKET_ERROR) {
        closesocket (ConnectSocket);
        //printf("Unable to connect to server: %i\n", WSAGetLastError());
        int Error = WSAGetLastError();
        cout << i <<": Unable to connect to server: " << Error << endl;
        WSACleanup();
        return 1;
    }

    //----------------------
    //Get local host name
    iResult = gethostname(name, sizeof(name));
    if (iResult == NO_ERROR) {
        printf("Host Name: %s\n", name);
    }
    else if (iResult == SOCKET_ERROR) {
        printf("Could not resolve host name: %i", WSAGetLastError());
    }

    //------------------------
    //Get peer name
    iResult = getpeername(ConnectSocket, (struct sockaddr*)&sName, &sNameSize);
    if (iResult == NO_ERROR)
        printf("Peer Name: %s\n", inet_ntoa(sName.sin_addr));
    else if (iResult == SOCKET_ERROR)
        printf("Could not get peer name: %i\n", WSAGetLastError());

    //-------------------------
    // Send an initial buffer
    iResult = send( ConnectSocket, sendbuf, (int)strlen(sendbuf), 0 );
    if (iResult == SOCKET_ERROR) {
        printf("send failed: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }
    else
        printf("Bytes Sent: %i\n", iResult);

    //-----------------------------
    // shutdown the connection since no more data will be sent
    iResult = shutdown(ConnectSocket, SD_SEND);
    if (iResult == SOCKET_ERROR) {
        printf("shutdown failed: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }

    // Receive until the peer closes the connection
    do {

        iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
        if ( iResult > 0 ) {
            printf("Bytes received: %d\n", iResult); //printf("Bytes received: %d\n", iResult);
            printf("From server: %s\n", recvbuf);
        }
        else if ( iResult == 0 )
            printf("Connection closed\n");
        else if (WSAERROR == WSAETIMEDOUT)
            printf("recv failed: WSAETIMEDOUT\n");
    } while( iResult > 0 );

    // cleanup
    closesocket(ConnectSocket);
    WSACleanup();
    system("PAUSE");
    return 0;
}

int main() {
        for (i;i>=50;i++) {
            PORT = i;
            sck();
        }
}

Answer 1

服务器可以无限期地打开套接字。

// Receive until the peer closes the connection

所以这会挂起你的应用程序。尝试连接到端口23，看看会发生什么。即使是网络服务器也可以延长端口的开放时间，用于链接(错误的字)请求，并且不需要重新连接的成本。

全局变量！

        PORT = i;
        sck();

全局变量。什么。不要这样做。函数应该是独立的(任何依赖于外部状态的东西都有可能出错，因为其他人会在最不经意的时候改变这种状态。将端口作为参数传递。

        sck(i);

Initialization

iResult = WSAStartup(MAKEWORD(2,2), &wsaData);

这只需要在应用程序中完成一次。所以您可以将它移出sck()函数。

不需要关闭从未打开的连接。

iResult = connect( ConnectSocket, (SOCKADDR*) &clientService, sizeof(clientService) );
if ( iResult == SOCKET_ERROR) {
    closesocket (ConnectSocket);  // Its not open at this point.

并非所有错误都是错误。

iResult = send( ConnectSocket, sendbuf, (int)strlen(sendbuf), 0 );

请参见人派：如果send()返回-1为错误，则需要检查errno以检查实际错误。并不是所有的错误都必须是终端机。EINTR不是一个问题。

不要等待服务器关闭对角.