Linux下面貌似没有什么直接开启或者关闭端口的命令，因为若仅仅只是开启了端口而不把它与进程相联系的话，端口的开启与关闭就显得毫无意义了（开了端口却没有程序处理进来的数据）。也就是说，Linux里面端口的活动与进程是紧密相连的，如果想要关闭某个端口，那么只要杀掉它对应的进程就可以了。

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客户端代码

include <stdio.h>

include <stdlib.h>

include <strings.h>

include <arpa/inet.h>

include <sys/socket.h>

int main(){

int sockfd = socket(AF_INET,SOCK_STREAM,0);

if(sockfd==-1)perror("sock");

struct sockaddr_in mine,dest;

bzero(&mine,sizeof(mine));mine.sin_family = AF_INET;mine.sin_port = htons(3334);inet_pton(AF_INET,"192.168.1.100",&mine.sin_addr);bzero(&dest,sizeof(dest));dest.sin_family = AF_INET;dest.sin_port = htons(9999);inet_pton(AF_INET,"192.168.1.100",&dest.sin_addr);int b = bind(sockfd,(struct sockaddr*)&mine,sizeof(mine));if(b==-1)perror("");int c = connect(sockfd,(struct sockaddr*)&dest,sizeof(dest));if(c!=0)perror("");close(sockfd);

}

服务端代码

include <stdio.h>

include <stdlib.h>

include <sys/socket.h>

include <arpa/inet.h>

include <strings.h>

int main(){

int sockfd = socket(AF_INET,SOCK_STREAM,0);

struct sockaddr_in addr;

bzero(&addr,sizeof(addr));

addr.sin_family = AF_INET;

addr.sin_port = htons(9999);

inet_pton(AF_INET,"192.168.1.100",&addr.sin_addr);

bind(sockfd,(struct sockaddr*)&addr,sizeof(addr));listen(sockfd,5);while(1){    struct sockaddr_in c_addr;    int c_len = sizeof(c_addr);    bzero(&c_addr,c_len);    int c = accept(sockfd,(struct sockaddr*)&addr,&c_len);    if(c==-1)perror("");    char ip[40]={0};    int port;    inet_ntop(AF_INET,&addr.sin_addr,ip,40);    port = ntohs(addr.sin_port);    printf("from %s:%d\n",ip,port);    close(c);}

}