one beacon packet from an 802.11 access point: analysis: 802.11 control packet/beacon (type 8) fixed initial hdr: 24 bytes management frame (control) no ds flags set 3 mac addresses dst: ff ff ff ff ff ff (bcast) src: agere AP (unicast) bss id: agere AP (same addr as src) wireless lan mgmt. frame (run on part), 68-24 = 44 bytes fixed params: 12 bytes tagged params: 32 bytes fixed params part: timestamp: 8 bytes beacon interval: 2 bytes (.1 sec) capability info: 2 bytes ESS no point coordination tagged parameters part: (TLV structure, with byte for T, byte for L) 1. SSID parameter tag (0) len: 8 data, essid string: xyzzyium 2. supported rates (speed): 1 len: 4 data, 1/2/5.5/11 mbits 3. DS parameter set (value = 3) len: 1 data, current channel 1 4. TIM, traffic indication map: (5) len: 4 data, DTIM count 0, DTIM period 1, bitmap (????) value in hex: 00 01 00 00 unknown tag at this point or garbage? -------------------------------------------------------------- details: Frame 1 (61 on wire, 61 captured) Arrival Time: Mar 7, 2002 19:28:56.750804000 Time delta from previous packet: 0.000000000 seconds Time relative to first packet: 0.000000000 seconds Frame Number: 1 Packet Length: 61 bytes Capture Length: 61 bytes IEEE 802.11 Type/Subtype: Beacon frame (8) Frame Control: 0x0080 Version: 0 Type: Management frame (0) Subtype: 8 Flags: 0x0 DS status: Not leaving DS or network is operating in AD-HOC mode (To DS: 0 From DS: 0) (0x00) .... .0.. = Fragments: No fragments .... 0... = Retry: Frame is not being retransmitted ...0 .... = PWR MGT: STA will stay up ..0. .... = More Data: No data buffered .0.. .... = WEP flag: WEP is disabled 0... .... = Order flag: Not strictly ordered Duration: 0 Destination address: ff:ff:ff:ff:ff:ff (ff:ff:ff:ff:ff:ff) Source address: 00:50:18:05:d0:f8 (00:50:18:05:d0:f8) BSS Id: 00:50:18:05:d0:f8 (00:50:18:05:d0:f8) Fragment number: 0 Sequence number: 2827 IEEE 802.11 wireless LAN management frame Fixed parameters (12 bytes) Timestamp: 0x000004CA3C13F150 Beacon Interval: 0.092160 [Seconds] Capability Information: 0x0001 .... ...1 = ESS capabilities: Transmitter is an AP .... ..0. = IBSS status: Transmitter belongs to a BSS ...0 .... = Privacy: AP/STA cannot support WEP ..0. .... = Short Preamble: Short preamble not allowed .0.. .... = PBCC: PBCC modulation not allowed 0... .... = Channel Agility: Channel agility not in use CFP participation capabilities: No point coordinator at AP (0x0000) Tagged parameters (25 bytes) Tag Number: 0 (SSID parameter set) Tag length: 8 Tag interpretation: xyzzyium Tag Number: 1 (Supported Rates) Tag length: 4 Tag interpretation: Supported rates: 1.0(B) 2.0(B) 5.5(B) 11.0(B) [Mbit/sec] Tag Number: 3 (DS Parameter set) Tag length: 1 Tag interpretation: Current Channel: 1 Tag Number: 5 ((TIM) Traffic Indication Map) Tag length: 4 Tag interpretation: DTIM count 0, DTIM period 1, Bitmap control 0x0, (Bitmap suppressed) 0000 80 00 00 00 ff ff ff ff ff ff 00 50 18 05 d0 f8 ...........P.... 0010 00 50 18 05 d0 f8 b0 b0 50 f1 13 3c ca 04 00 00 .P......P..<.... 0020 5a 00 01 00 00 08 XX YY ZZ ZZ YY 69 75 6d 01 04 Z.....xyzzyium.. 0030 82 84 8b 96 03 01 01 05 04 00 01 00 00 .............