如何接收与原始套接字用C ICMP请求 [英] How to receive ICMP request in C with raw sockets

问题描述

。这是一项任务，它必须与原始套接字。我想编写一个简单的ICMP PING。
我用这个作为基础 http://www.pdbuchan.com/rawsock/icmp4.c 。在线路127是为wlan0，进出口使用的eth0。在290线I codeD这样的：

.This is an assignment, it has to be with raw sockets. I need to program a simple icmp ping. I used this as a base http://www.pdbuchan.com/rawsock/icmp4.c . At line 127 is wlan0, Im using eth0. In line 290 I coded this:

`

 struct sockaddr_in rec;

  unsigned char * pkt = (unsigned char *) malloc (IP_MAXPACKET * sizeof (unsigned char));

  if (recvfrom (sd, (void*)pkt, IP4_HDRLEN + ICMP_HDRLEN+datalen , 0, NULL, (socklen_t*)sizeof (struct sockaddr)) < 0)  {
    perror ("recvfrom() failed ");
    exit (EXIT_FAILURE);
  }
  struct ip *ip = (struct ip *)pkt;
  struct icmphdr *icmp = (struct icmphdr *)(pkt + IP4_HDRLEN);

  printf("%s %s %d\n",(char*)inet_ntoa(*(struct in_addr*)&ip->ip_dst),
            (char*)inet_ntoa(*(struct in_addr*)&ip->ip_src),
        icmp->type);
  free (pkt);

`
问题是，ip_dst和ip_src被示为我的机器的IP和ICMP类型为0并且不8. Wireshark的同时显示ICMP回应和请求。
也许我recvfrom的是错的，但我听说过一些关于Linux自己的TCP / IP可能被处理的数据包。如果这是真的，有什么解决办法是什么？

` The problem is that ip_dst and ip_src are being shown as my machines's IP, and icmp type as 0 and not 8. Wireshark shows both icmp reply and request. Probably my recvfrom is wrong, but I heard something about linux own TCP/IP might be handling the packets. If that's true, what is the workaround for that?

编辑：我检查这个原始套接字监听但它并没有解决我的问题。

edit: I checked this raw socket listener but it did not solve my problem.

推荐答案

我不认为你可以使用IPPROTO_RAW时得到答复。

I don't think you can get a reply when using IPPROTO_RAW.

您必须使用

socket (AF_INET, SOCK_RAW, IPPROTO_ICMP);

使用IPPROTO_ICMP必须只发送一个ICMP数据包，而不是整个IP包。

With IPPROTO_ICMP you must only send an ICMP packet, not the whole IP packet.

在接收但是你会得到整个IP数据包，并要提取的ICMP回复。请注意，您将获得向主机发送ICMP包的副本，所以你必须进行过滤。

When receiving however you'll get the whole IP packet and have to extract the ICMP reply. Note that you will get a copy of all ICMP packets sent to the host so you must filter them.

看灵感真正的平。

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