抓包工具已经看到数据到本机,但是recvfrom 读不到数据的问题?

2012-07-10 05:21:11 1.2k 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

Centos7 多网卡抓包可以抓到UDP但程序recvfrom不到问题： Centos7多网卡，抓包时发现某网卡上有UDP包，但是用程序recvfrom无法接收到消息。解决步骤: 1.确认防火墙是否关闭；已关闭 2.确认网卡是否开启过滤：cat/proc/sys/net/ipv4/conf/ethxxx/rp_filter (ethxxx是网卡名称) 结果：已关闭(当然此配置项只影响组播，这是病急乱投医) 3.随便找一个服务端... 阅读详情



#include "stdafx.h"

#include <WinSock2.h>

#include <MSWSock.h>

#pragma comment(lib, "ws2_32.lib")

#include <list>

#include <vector>

#include <string>

#include <iostream>



DWORD WINAPI EchoProc(LPVOID pVoid)

{

	SOCKET ReceivingSocket = (SOCKET)pVoid;

	char szRecvBuf[8193]={0};

	sockaddr_in SenderAddr;

	int nAddrLen   =   sizeof(SenderAddr); 

	int nRecvdBytes = 0;

	int Ret = 0;

	while(true) 

	{ 

		if((nRecvdBytes   =   recvfrom(ReceivingSocket,   szRecvBuf,   8192,   0,   (sockaddr*)&SenderAddr,   &nAddrLen))   ==   SOCKET_ERROR) 

		{ 

			cout<<"ERROR:   recvfrom   failed   with   error:   " <<WSAGetLastError() <<endl; 

			break; 

		} 

		else

		{

			szRecvBuf[nRecvdBytes] = 0;

			cout<<szRecvBuf<<endl;

		}

		

		Ret   =   sendto(ReceivingSocket,   szRecvBuf,   nRecvdBytes,   0,   (SOCKADDR   *)&SenderAddr,   nAddrLen); 

		if(SOCKET_ERROR   ==   Ret) 

		{ 

			cout<<"ERROR:   sendto   failed   with   error:   " <<WSAGetLastError() <<endl; 		

			break; 

		} 

	} 	

	

	closesocket(ReceivingSocket); 

	WSACleanup(); 

	

	return 0;

}





DWORD WINAPI RecvProc(LPVOID pVoid)

{

	SOCKET ReceivingSocket = (SOCKET)pVoid;

	char szRecvBuf[8193]={0};

	sockaddr_in SenderAddr;

	int nAddrLen   =   sizeof(SenderAddr); 

	int nRecvdBytes = 0;

	int Ret = 0;

	while(true) 

	{ 

		if((nRecvdBytes   =   recvfrom(ReceivingSocket,   szRecvBuf,   8192,   0,   (sockaddr*)&SenderAddr,   &nAddrLen))   ==   SOCKET_ERROR) 

		{ 

			cout<<"ERROR:   recvfrom   failed   with   error:   " <<WSAGetLastError() <<endl; 

			break; 

		} 

		else

		{

			szRecvBuf[nRecvdBytes] = 0;

			cout<<szRecvBuf<<endl;

		}		 

	} 	

	

	closesocket(ReceivingSocket); 

	WSACleanup(); 

	

	return 0;

}





SOCKET sock = INVALID_SOCKET;

int main(int argc, TCHAR* argv[], TCHAR* envp[])

{

	int nRetCode = 0;

	

	WSADATA wsaData;

	WSAStartup(MAKEWORD(2,2), &wsaData);

	sockaddr_in sockaddr;

	sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP );

	BOOL   bNewBehavior   =   FALSE;   

	DWORD   dwBytesReturned; 

	WSAIoctl(sock,   SIO_UDP_CONNRESET,   &bNewBehavior,   sizeof   bNewBehavior,   NULL,   0,   &dwBytesReturned,   NULL,   NULL);

	

	int mode = 0;

SELECT_MODE:

	cout << "输入模式:0服务端 1客户端" << endl;

	cin>>mode;

	if (mode == 0)

	{

		int port = 0;

		cout << "输入监听端口" << endl;

		cin>>port;

		

		sockaddr.sin_family = AF_INET;

		sockaddr.sin_port = htons(port);

		sockaddr.sin_addr.S_un.S_addr = htons(INADDR_ANY);

		

		if(bind(sock, (SOCKADDR*)&sockaddr, sizeof(sockaddr)) != SOCKET_ERROR)

		{				

			HANDLE hThread = CreateThread(NULL, 0, EchoProc, (void*)sock, 0, NULL);

			char q = 0;

			while (true)

			{

				cout<<"press q to quit"<<endl;

				cin>>q;

				if (q == 'q')

				{

					closesocket(sock);

					WaitForSingleObject(hThread, INFINITE);

					CloseHandle(hThread);

					break;

				}

			}

		}

		

	}

	else if (mode == 1)

	{

		string ip;

		int port = 0;

		sockaddr_in addr;

		addr.sin_family = AF_INET;

SELECT_IP:

		cout << "输入服务IP" << endl;

		cin>>ip;

		PHOSTENT phost = gethostbyname(ip.c_str());

		if (phost == NULL)

		{

			goto SELECT_IP;

		}

		else

		{

			addr.sin_addr.S_un.S_addr = *(u_long *) phost->h_addr_list[0];; //inet_addr(ip.c_str());

		}

		

		cout<<"输入端口"<<endl;

		cin>>port;

		addr.sin_port = htons(port);

		

		cout<<"输入要发送的数据"<<endl;

		

		

		sockaddr_in bind;

		bind.sin_addr.S_un.S_addr = htons(INADDR_ANY);

		bind.sin_port = htons(port-1);

		bind.sin_family = AF_INET;

		::bind(sock, (SOCKADDR*)&bind, sizeof(bind));

		

		HANDLE hThread = CreateThread(NULL, 0, RecvProc, (void*)sock, 0, NULL);

		

		char q = 0;

		cout<<"press q to quit"<<endl;

		while (true)

		{

			string buffer;

			cin>>buffer;

			int sendResult = sendto(sock, buffer.c_str(), buffer.size(), 0, (SOCKADDR*)&addr, sizeof(addr));

			

			cin>>q;

			if (q == 'q')

			{

				closesocket(sock);

				WaitForSingleObject(hThread, INFINITE);

				CloseHandle(hThread);

				break;

			}				

		}

		

	}

	else

	{

		cout << "输入正确的的模式" << endl;

		goto SELECT_MODE;

	}

	

	

	return nRetCode;

}

这是一个简单的upd 回显程序,运行程序选择0,就是服务端,输入监听端口之后,客户端开始网这个端口发数据,服务端就会把数据打出来,然后在发回客户端.

这个在本机上运行是好的

一台机器是win7 ip:192.168.0.195
一台机器是xp ip:192.168.0.134
都关闭了防火墙,360之类的碉东西
都是用网线连接到路由器的

现在的问题是
如果从win7向xp发包,xp机器能正常收到

如果是xp向win7发包,在win7上打开的抓包程序也都能看到包到本机了,但是就是recvfrom读不到数据.

哪位朋友提供下思路,怎么寻找根源问题.

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