scan.c

Linux下的端口扫描器

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <netdb.h>
#include <signal.h>

void usage(){
    printf("===========chenkaihui ==========\n");
    printf("usage:scan 192.168.1.1 1 1000\n");

}

main(int argc,char **argv){
    int startport = 0;
    int endport = 0;
    int probeport  = 0;
    struct hostent *host;
    int err , i ,net;
    struct sockaddr_in sa;
    if (argc != 4){
	usage();
	exit(1);
    }
    startport = atoi(argv[2]);
    endport = atoi(argv[3]);
    for ( i = startport; i < endport ; i++){
	strncpy((char *)&sa , "" , sizeof sa);
	sa.sin_family = AF_INET;
	if (isdigit( *argv[1])){
	    sa.sin_addr.s_addr = inet_addr(argv[1]);
	}else if ((host = gethostbyname(argv[1])) != 0){
	    strncpy((char *)&sa.sin_addr , (char *) host->h_addr , sizeof sa.sin_addr);
	}else{
	    herror(argv[1]);
	    exit(2);
	}
    sa.sin_port = htons(i);
    net = socket(AF_INET , SOCK_STREAM , 0);
    if (net < 0 ){
	perror("\n socket");
	exit(2);
    }
    err = connect(net , (struct sockaddr *)&sa , sizeof sa);
    if (err < 0 ){
	printf("%s %-5d %s \r" , argv[1] , i , strerror(errno));
	fflush(stdout);
    }else{
	printf("%s %-5d accepted. \n" , argv[1] , i);
	if( shutdown(net , 2) < 0  ){
	    perror("\n shutdown");
	    exit(2);
	}
    }
    close(net);
    }
    printf("\r\n");
    fflush(stdout);
    return(0);
}