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PORAW Socket - Ethertype and receive's algorithm - C
 

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  1. PORAW Socket - Ethertype and receive's algorithm - C
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    <p>I'm working with raw socket in C language. I need to send and to receive a raw ethernet packet. The packet should start with an IEEE 802.3 header:</p> <p><em>MAC DST [0-5] - MAC SRC [6-11] - ETH TYPE[12-13]</em></p> <p>Catching the packets with wireshark I see the following structure:</p> <p><em>MAC DST [0-5] - MAC SRC [6-11] - LENGTH[12-13] - TRAILER[14-58]-....</em></p> <p>This is my code:</p> <pre><code>... sraw = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_802_3)); ... retVal = setsockopt(sraw, SOL_SOCKET, SO_BINDTODEVICE, (void *)&amp;ifr, sizeof(ifr)); ... val = 3; retVal = setsockopt(sraw, SOL_SOCKET, SO_PRIORITY, &amp;val, sizeof (val)); ... memcpy(ptr_eth_header-&gt;DstMac, dst_mac, 6); memcpy(ptr_eth_header-&gt;SrcMac, src_mac, 6); ptr_eth_header-&gt;Type = htons(ETH_P_802_3); memcpy(buffer + ETHHDR_SIZE, data, 60); ... sockaddr.sll_family = htons(PF_PACKET); sockaddr.sll_protocol = htons(ETH_P_802_3); sockaddr.sll_ifindex = ifr.ifr_ifru.ifru_ivalue; sockaddr.sll_halen = 6; memcpy(&amp;(sockaddr.sll_addr), dst_mac, 6); ... bytes = sendto(sraw, buffer, sizeof(buffer), 0, (struct sockaddr *) &amp;(sockaddr), sizeof (struct sockaddr_ll)); </code></pre> <p>Is it just a wireshark's "problem"? Any ideas?</p> <p>My second problem is about the receipt of the raw messages. The process is stuck on the recvfrom.</p> <p>This is my code:</p> <pre><code>sraw = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_802_3)); ... retVal = setsockopt(sraw, SOL_SOCKET, SO_BINDTODEVICE, (void *)&amp;ifr, sizeof(ifr)); ... val = 3; retVal = setsockopt(sraw, SOL_SOCKET, SO_PRIORITY, &amp;val, sizeof (val)); ... val = CLIENT_PACKET_SIZE; retVal = setsockopt(sraw, SOL_SOCKET, SO_RCVBUF, &amp;val, sizeof (val)); sockaddr.sll_family = htons(PF_PACKET); sockaddr.sll_ifindex = ifr.ifr_ifindex; sockaddr.sll_protocol = htons(ETH_P_802_3); buffer = malloc(CLIENT_PACKET_SIZE * sizeof(char)); while (count &lt; PACKET_COUNT) { bytes = recvfrom(sraw, buffer, CLIENT_PACKET_SIZE, 0, (struct sockaddr *)&amp;sockaddr, (socklen_t*)sizeof(sockaddr)); ... } </code></pre> <p>Could you help me?</p> <p>Thanks in advance!</p>
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    1. USRichard J. Ross III
    1. USSimone
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      1. PORAW Socket - Ethertype and receive's algorithm - C
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    1. COIs your header structure packed? What is the `sizeof(buffer)`?
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      1. PORAW Socket - Ethertype and receive's algorithm - C
      1. USNikolai Fetissov
    2. COYes it is. `typedef struct { char DstMac[6]; char SrcMac[6]; short int Type; } HEADER;` `sizeof(buffer)` is 64.
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    3. COAre you able to verify a packet is sent/received by the NIC using Wireshark independently of your program?
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      1. USIoan
 

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