Help needed with Constructing radiotap header and ieee80211 header structures

Help needed with Constructing radiotap header and ieee80211 header structures

[Anand Madhusoodanan]

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Hi ,
I need some help with a Wifi experiment i am trying to set up.
I am trying to communicate between two laptop machines using Wifi. 

The structure of the radiotap header 
and ieee80211 header i am using are

 struct ieee80211_radiotap_header {
unsigned char it_version;
uint16_t it_len;        
uint32_t it_present;
 };

 /* Structure for 80211 header */

 struct ieee80211_hdr_3addr {
    uint16_t frame_ctl[2];
    uint16_t duration_id;
    unsigned char addr1[ETH_ALEN];
    unsigned char addr2[ETH_ALEN];
    unsigned char addr3[ETH_ALEN];
    uint16_t seq_ctl;
  };

struct packet {
   struct ieee80211_radiotap_header rtap_header;
   struct ieee80211_hdr_3addr iee802_header;
   unsigned char payload[30];

  };

  /* In main program */

   struct packet mypacket;
   struct ieee80211_radiotap_header ratap_header;
   struct ieee80211_hdr_3addr iee802_header;

   unsigned char addr1[ETH_ALEN] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};  /* broadcast address */
   unsigned char addr2[ETH_ALEN] = {0x28,0xcf,0xda,0xde,0xd3,0xcc};  /* mac address of   
                                                                      network card */
   unsigned char addr3[ETH_ALEN] = {0xd8,0xc7,0xc8,0xd7,0x9f,0x21};   /* mac address of   
                                                  access point i am trying to connect to */

  /* Radio tap header data */
   ratap_header.it_version = 0x00;
   ratap_header.it_len = 0x07;      
   ratap_header.it_present =  (1 << IEEE80211_RADIOTAP_RATE);

   mypacket.rtap_header = ratap_header;

   /* ieee80211 header data */

    iee802_header.frame_ctl[0] = IEEE80211_FC0_VERSION_0  |
                                                   IEEE80211_FC0_TYPE_MGT | 
                                                    IEEE80211_FC0_SUBTYPE_BEACON;

   iee802_header.frame_ctl[1] =IEEE80211_FC1_DIR_NODS;
    strcpy(iee802_header.addr1,addr1);
    strcpy(iee802_header.addr2,addr2);
    strcpy(iee802_header.addr3,addr3);
    iee802_header.seq_ctl = 0x1086;

    mypacket.iee802_header=iee802_header;

   /* Payload */

   unsigned char payload[PACKET_LENGTH]="temp";

   strcpy(mypacket.payload , payload);

I am able to receive the packets when i test the transmission 
and reception on the same laptop. However i 
am not able to receive the packet transmitted on a 
different laptop. Wireshark does not show the packet 
as well. Can you point out the mistake i am making?

Thanks and Regards,
Anand.


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