linux c快速判断tcp端口

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>

int main(int argc, char *argv[]) {
    if (argc != 2) {
        fprintf(stderr, "Usage: %s <port>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    int port = atoi(argv[1]);
    int sockfd;
    struct sockaddr_in serv_addr;

    // 创建socket
    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket");
        exit(EXIT_FAILURE);
    }

    // 设置服务器地址结构体
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(port);
    serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");

    // 尝试连接
    if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) == 0) {
        printf("Port %d is open\n", port);
    } else {
        perror("connect");
        printf("Port %d is closed or filtered\n", port);
    }

    // 关闭socket
    close(sockfd);

    return 0;
}