projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / blame
| Commit | Line | Data |
|---|---|---|
| 08d1f215 AG |
1 | How to use packet injection with mac80211 |
| 2 | ========================================= | |
| 3 | ||
| 4 | mac80211 now allows arbitrary packets to be injected down any Monitor Mode | |
| 5 | interface from userland. The packet you inject needs to be composed in the | |
| 6 | following format: | |
| 7 | ||
| 8 | [ radiotap header ] | |
| 9 | [ ieee80211 header ] | |
| 10 | [ payload ] | |
| 11 | ||
| 12 | The radiotap format is discussed in | |
| 13 | ./Documentation/networking/radiotap-headers.txt. | |
| 14 | ||
| 15 | Despite 13 radiotap argument types are currently defined, most only make sense | |
| 16 | to appear on received packets. Currently three kinds of argument are used by | |
| 17 | the injection code, although it knows to skip any other arguments that are | |
| 18 | present (facilitating replay of captured radiotap headers directly): | |
| 19 | ||
| 20 | - IEEE80211_RADIOTAP_RATE - u8 arg in 500kbps units (0x02 --> 1Mbps) | |
| 21 | ||
| 22 | - IEEE80211_RADIOTAP_ANTENNA - u8 arg, 0x00 = ant1, 0x01 = ant2 | |
| 23 | ||
| 24 | - IEEE80211_RADIOTAP_DBM_TX_POWER - u8 arg, dBm | |
| 25 | ||
| 26 | Here is an example valid radiotap header defining these three parameters | |
| 27 | ||
| 28 | 0x00, 0x00, // <-- radiotap version | |
| 29 | 0x0b, 0x00, // <- radiotap header length | |
| 30 | 0x04, 0x0c, 0x00, 0x00, // <-- bitmap | |
| 31 | 0x6c, // <-- rate | |
| 32 | 0x0c, //<-- tx power | |
| 33 | 0x01 //<-- antenna | |
| 34 | ||
| 35 | The ieee80211 header follows immediately afterwards, looking for example like | |
| 36 | this: | |
| 37 | ||
| 38 | 0x08, 0x01, 0x00, 0x00, | |
| 39 | 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, | |
| 40 | 0x13, 0x22, 0x33, 0x44, 0x55, 0x66, | |
| 41 | 0x13, 0x22, 0x33, 0x44, 0x55, 0x66, | |
| 42 | 0x10, 0x86 | |
| 43 | ||
| 44 | Then lastly there is the payload. | |
| 45 | ||
| 46 | After composing the packet contents, it is sent by send()-ing it to a logical | |
| 47 | mac80211 interface that is in Monitor mode. Libpcap can also be used, | |
| 48 | (which is easier than doing the work to bind the socket to the right | |
| 49 | interface), along the following lines: | |
| 50 | ||
| 51 | ppcap = pcap_open_live(szInterfaceName, 800, 1, 20, szErrbuf); | |
| 52 | ... | |
| 53 | r = pcap_inject(ppcap, u8aSendBuffer, nLength); | |
| 54 | ||
| 55 | You can also find sources for a complete inject test applet here: | |
| 56 | ||
| 57 | http://penumbra.warmcat.com/_twk/tiki-index.php?page=packetspammer | |
| 58 | ||
| 59 | Andy Green <andy@warmcat.com> |