Port Scanning In CPP

port-scanner.cpp

#include <iostream>
#include <cstring>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <vector>

using namespace std;

vector<int> ports = {21, 22, 23, 25, 80, 110, 443};

int main(int argc, char* argv[]) {
    if (argc != 2) {
        cout << "Usage: %s <IP address>" << endl;
        return -1;
    }

    char* target = argv[1];

    for (int port : ports) {
        int sock = socket(AF_INET, SOCK_STREAM, 0);
        if (sock == -1) {
            cout << "Could not create socket." << endl;
            return -1;
        }

        sockaddr_in addr;
        memset(&addr, 0, sizeof(addr));
        addr.sin_family = AF_INET;
        addr.sin_port = htons(port);
        inet_pton(AF_INET, target, &addr.sin_addr);

        int res = connect(sock, (sockaddr*) &addr, sizeof(addr));
        if (res == -1) {
            cout << "Port " << port << " is closed." << endl;
        } else {
            cout << "Port " << port << " is open." << endl;
        }

        close(sock);
    }

    return 0;
}