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| 关键词： PORT time include struct host addr char family Address ports |
#include <stdio.h>#include <unistd.h> // Defines implementation characteristics identified by POSIX standard.#include <sys/types.h> // data types#include <sys/socket.h> // Internet Protocol family#include <netdb.h> // definitions for network database operations#include <netinet/in.h> // Internet Protocol family#include <time.h> // standard time functions#define START_PORT 1#define END_PORT 100 // define constants/*Structures used, included for informational/testing purposes onlystruct sockaddr_in short int sin_family // Address family unsigned short int sin_port // Port number struct in_addr sin_addr // Internet address unsigned char sin_zero[8] // Same size as struct sockaddrstruct hostent char *h_name // name of the host char **h_aliases // A pointer to an array of pointers to alternative host names int h_addrtype // Address type being returned int h_length // The length of address in bytes char **h_addr_list // network addresses for the host, terminated by a null pointer struct servent char *s_name; // official service name char **s_aliases; // alias list int s_port; // port number char *s_proto; // protocol to use*/ int main(int argc, char **argv) { // declare data types int socket_fd, port, start_port, end_port, open_ports, closed; time_t time1, time2; struct hostent *host; struct sockaddr_in target; struct servent* sp; float diff; // initiate variables open_ports = 0; closed = 0; // check for command line arguements if (argc<2) exit(printf("usage: %s <hostname>\n", argv[0])); // get hostname or exit with error host = gethostbyname(argv[1]); if (!host) exit(printf("Error looking up hostname.\n")); // specify address family target.sin_family = AF_INET; target.sin_addr.s_addr = *(long *)(host->h_addr); // get intitial clock time time1 = time(NULL); printf("scanning ports %d - %d on %s (%s)\n\n",START_PORT, END_PORT, inet_ntoa(*((struct in_addr *)host->h_addr)), host->h_name); printf("port \t state \t service\n"); // loop through all ports specified for (port=START_PORT; port <= END_PORT; port++) { // convert ip to network based order target.sin_port = htons(port); // here we create the socket that returns a file desriptor // AF_INET = address family // SOCK_STREAM - basic TCP socket reliable, two-way, connection-based byte streams. // 0 - set protocol type socket_fd =socket(AF_INET,SOCK_STREAM,0); if (socket_fd < 0) exit(printf("Error creating socket.\n")); // check port is open if (!connect(socket_fd,(struct sockaddr *)&target, sizeof(target))) { // increment no of open ports open_ports++; // getservbyport tries to convert port to service name. checks /etc/services by default sp = getservbyport(htons(port),"tcp"); // output printf("%i/tcp \t open \t %s\n", port,sp->s_name); } // if port closed, increment closed count else closed++; // clean up / close socket if (close(socket_fd)) exit(printf("error closing socket.\n")); } // end for loop // get final time time2 = time(NULL); // calculate time difference diff = difftime(time2,time1); // check if there are no open ports if(open_ports < 1) printf("No open ports found"); // (int)diff may return 0 if scanning localhost - yes its so fast ;) printf("\nScan completed in %d seconds, %d ports open, %d closed\n", (int)diff, open_ports, closed); return 0;}/* This is a simple port scanner written in c, it will basically do the same thing as nmap -sT <host> which is the default TCP connect scan. I do not recommend using it as it is quite slow, its purpose is to show you some basic socket usage in c.*/ |
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