服務端程式：

#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <malloc.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>
#include <stdarg.h>
#include <fcntl.h>

int main()
{
	int sockSrv = socket(AF_INET, SOCK_STREAM, 0);

	struct sockaddr_in addrSrv;
	addrSrv.sin_family = AF_INET;
	addrSrv.sin_addr.s_addr = INADDR_ANY; 
	addrSrv.sin_port = htons(8765);

	bind(sockSrv, (const struct sockaddr *)&addrSrv, sizeof(struct sockaddr_in));

	listen(sockSrv, 5);

	struct sockaddr_in addrClient;
	int len = sizeof(struct sockaddr_in);

	int sockConn = accept(sockSrv, (struct sockaddr *)&addrClient, (socklen_t*)&len);

	while(1)  
	{  
		getchar();	
		char szRecvBuf[50001] = {0};  
		int iRet = recv(sockConn, szRecvBuf, sizeof(szRecvBuf) - 1, 0);  
		printf("iRet is %d\n", iRet);	
	}  
	
	close(sockConn);
	close(sockSrv);
	
	return 0;
}
 

       客戶端程式：

#include <unistd.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <malloc.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>
#include <stdarg.h>
#include <fcntl.h>

int main()
{
    int sockClient = socket(AF_INET, SOCK_STREAM, 0);

    struct sockaddr_in addrSrv;
    addrSrv.sin_addr.s_addr = inet_addr("10.100.70.140");
    addrSrv.sin_family = AF_INET;
    addrSrv.sin_port = htons(8765);
    connect(sockClient, ( const struct sockaddr *)&addrSrv, sizeof(struct sockaddr_in));

	#define N 2000
	char szSendBuf[N] = {0};
	for(unsigned int i = 0; i < N; i++) //字元陣列最後一個字元不要求是‘\0’
	{
		szSendBuf[i] = 'a';	
	}

	int total = 0;
	while(1)
	{
		int iRet = send(sockClient, szSendBuf, sizeof(szSendBuf) , 0); 
		total += iRet;
		printf("iRet is %d, total send is %d\n", iRet, total);
		getchar();
	}

    close(sockClient);

    return 0;
}
 

       這個問題非常有意思， 其實客戶端是發了FIN包的， 至於為什麼tcpdump抓不到包， 且服務端socket狀態沒有變化（無感知）， 大家可以思考一下。