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POHow do I receive raw, layer 2 packets in C/C++?
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  1. POHow do I receive raw, layer 2 packets in C/C++?
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    copied!<p>How do I receive layer 2 packets in POSIXy C++? The packets only have src and dst MAC address, type/length, and custom formatted data. They're not TCP or UDP or IP or IGMP or ARP or whatever - they're a home-brewed format given unto me by the Hardware guys.</p> <p>My <code>socket(AF_PACKET, SOCK_RAW, IPPROTO_RAW)</code> never returns from its <code>recvfrom()</code>.</p> <p>I can send fine, I just can't receive no matter what options I fling at the network stack.</p> <p>(Platform is VxWorks, but I can translate POSIX or Linux or whatever...)</p> <p>receive code (current incarnation):</p> <pre><code> int s; if ((s = socket(AF_PACKET, SOCK_RAW, IPPROTO_RAW)) &lt; 0) { printf("socket create error."); return -1; } struct ifreq _ifr; strncpy(_ifr.ifr_name, "lltemac0", strlen("lltemac0")); ioctl(s, IP_SIOCGIFINDEX, &amp;_ifr); struct sockaddr_ll _sockAttrib; memset(&amp;_sockAttrib, 0, sizeof(_sockAttrib)); _sockAttrib.sll_len = sizeof(_sockAttrib); _sockAttrib.sll_family = AF_PACKET; _sockAttrib.sll_protocol = IFT_ETHER; _sockAttrib.sll_ifindex = _ifr.ifr_ifindex; _sockAttrib.sll_hatype = 0xFFFF; _sockAttrib.sll_pkttype = PACKET_HOST; _sockAttrib.sll_halen = 6; _sockAttrib.sll_addr[0] = 0x00; _sockAttrib.sll_addr[1] = 0x02; _sockAttrib.sll_addr[2] = 0x03; _sockAttrib.sll_addr[3] = 0x12; _sockAttrib.sll_addr[4] = 0x34; _sockAttrib.sll_addr[5] = 0x56; int _sockAttribLen = sizeof(_sockAttrib); char packet[64]; memset(packet, 0, sizeof(packet)); if (recvfrom(s, (char *)packet, sizeof(packet), 0, (struct sockaddr *)&amp;_sockAttrib, &amp;_sockAttribLen) &lt; 0) { printf("packet receive error."); } // code never reaches here </code></pre>
 

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