Port Scanner in C++
 

Hi all

I was looking for a port scanner to see what was open on my laptop and I thought as I was learning C++ why not search for a C++ port scanner. I came across this code I can make sense of most of it but it wont compile. I have linked the -lws2_32 file that I was told is needed because I use Dev, I looked in Project -> Project Options -> Parameters -> and i went to the little folder icon and searched for the library in the lib but it wasn't there is i just went to the "Linker" edit box and typed -lws2_32 but that didn't work either. Here is the code

/*--------------------

| if your using dev-c++

| you need to link

| -lws2_32

| to your application

---------------------*/



#include <winsock2.h>

#include <iostream>

using namespace std;



char IP[20];

int start, end, temp, err, nret;

SOCKET sock;

SOCKADDR_IN Info;

WSADATA wsadata;

  

int main()

{

   err = WSAStartup(MAKEWORD(2, 2), &wsadata);

   if(err != 0)

   {

      cout << "Error with winsock. Will Now Exit." << endl;

      cin.get();

      return 0;

   }

  

   cout << "Target IP: ";

   cin>>IP;

   cout << "Starting Port: ";

   cin>>start;

   cout << "End Port: ";

   cin>>end;

  

   cin.ignore();

  

   cout << endl << endl << "Starting Scan..." << endl << endl;

  

   temp = start;

   while(temp < end)

   {

      sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    

      Info.sin_family = AF_INET;

      Info.sin_port = htons(start);

      nret = connect(sock, NULL, NULL);

      // error is for line above

      if(nret != SOCKET_ERROR)

      {

         cout << "Port " << temp << " - OPEN! " << endl;

      }

      temp++;

      closesocket(sock);

    }

    cout << endl << "Finished With Scan..." << endl;

    

    cin.get();

    return 0;

}

These are the error messages I am getting on line 46 it has a comment underneath
C:\Dev-Cpp\port.cpp In function `int main()':
C:\Dev-Cpp\port.cpp [Warning] passing NULL used for non-pointer converting 3 of `int connect(SOCKET, const sockaddr*, int)'
[Linker error] undefined reference to `__cpu_features_init'
C:\Dev-Cpp\port.cpp ld returned 1 exit status

Can someone please explain what is wrong, I think it is because I am not linking that file correctly?


Cheers

HLA91

Re: Port Scanner in C++
 

C++ is a little bit more strict about how it defines NULL than C. The compiler is complaining because you are passing a (void *)0 as the third argument, when it expects an (int)0.

Hope this helps.

Re: Port Scanner in C++
 

Can you explain in a bit more detail please, I don't quite get what you are saying?

Re: Port Scanner in C++
 

Say
nret = connect(sock, NULL, 0);

C++ defines NULL as a pointer.