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Port scanner in C

Discussion in 'C' started by shukad33, Jun 9, 2008.

  1. shukad33

    shukad33 New Member

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    Port scanner in C
    Code:
    #include<stdio.h>
    #include<sys/socket.h>
    #include<sys/types.h>
    #include<stdlib.h>
    #include<netdb.h>
    int main(int argc,char **argv)
    {
    	int i,err,net;
    	struct hostent *host;
    	struct sockaddr_in sa;
    	if(argc!=2)
    	{
    		printf("Error...Usage :%s ip-address",argv[0]);
    		exit(0);
    	}
    	for(i=1;i<20000;i++)
    	{
    		sa.sin_family=AF_INET;
    		sa.sin_port=htons(i);
    		sa.sin_addr.s_addr=inet_addr(argv[1]);
    		net=socket(AF_INET,SOCK_STREAM,0);
    		err=connect(net,(struct sockaddr_in *)&sa,sizeof(sa));
    		if(err>=0)
    		{
    			printf("\n%d is open",i);
    		}
    	}
    	printf("\n");
     }
     
  2. shabbir

    shabbir Administrator Staff Member

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    Can you explain how do I get the following header files. sys/socket.h
     
  3. madlex

    madlex New Member

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    You are opening 20000 connections and you are closing none of them.
    You should close connections in your for.

    Code:
    if(err>=0)
            {
                printf("\n%d is open",i);
            }
    This is wrong. Values over zero may express an error, not a succesful connection.
    You should really interpret this values and the print a correct output.
    (hint: will return 0 on success).

    You didn't specify the platform. For windows platform is necesary to call WSAStartup, to initialize the winsock library, otherwise you will receive errors from each call made to winsock's API.
     
  4. shukad33

    shukad33 New Member

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    Its a unix platform supported program. Hence it is assumed to be available in UNIX...
     

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