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Diffstat (limited to 'Documentation/networking/mac80211-injection.txt')
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diff --git a/Documentation/networking/mac80211-injection.txt b/Documentation/networking/mac80211-injection.txt new file mode 100644 index 00000000000..53ef7a06f49 --- /dev/null +++ b/Documentation/networking/mac80211-injection.txt @@ -0,0 +1,59 @@ +How to use packet injection with mac80211 +========================================= + +mac80211 now allows arbitrary packets to be injected down any Monitor Mode +interface from userland. The packet you inject needs to be composed in the +following format: + + [ radiotap header ] + [ ieee80211 header ] + [ payload ] + +The radiotap format is discussed in +./Documentation/networking/radiotap-headers.txt. + +Despite 13 radiotap argument types are currently defined, most only make sense +to appear on received packets. Currently three kinds of argument are used by +the injection code, although it knows to skip any other arguments that are +present (facilitating replay of captured radiotap headers directly): + + - IEEE80211_RADIOTAP_RATE - u8 arg in 500kbps units (0x02 --> 1Mbps) + + - IEEE80211_RADIOTAP_ANTENNA - u8 arg, 0x00 = ant1, 0x01 = ant2 + + - IEEE80211_RADIOTAP_DBM_TX_POWER - u8 arg, dBm + +Here is an example valid radiotap header defining these three parameters + + 0x00, 0x00, // <-- radiotap version + 0x0b, 0x00, // <- radiotap header length + 0x04, 0x0c, 0x00, 0x00, // <-- bitmap + 0x6c, // <-- rate + 0x0c, //<-- tx power + 0x01 //<-- antenna + +The ieee80211 header follows immediately afterwards, looking for example like +this: + + 0x08, 0x01, 0x00, 0x00, + 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, + 0x13, 0x22, 0x33, 0x44, 0x55, 0x66, + 0x13, 0x22, 0x33, 0x44, 0x55, 0x66, + 0x10, 0x86 + +Then lastly there is the payload. + +After composing the packet contents, it is sent by send()-ing it to a logical +mac80211 interface that is in Monitor mode. Libpcap can also be used, +(which is easier than doing the work to bind the socket to the right +interface), along the following lines: + + ppcap = pcap_open_live(szInterfaceName, 800, 1, 20, szErrbuf); +... + r = pcap_inject(ppcap, u8aSendBuffer, nLength); + +You can also find sources for a complete inject test applet here: + +http://penumbra.warmcat.com/_twk/tiki-index.php?page=packetspammer + +Andy Green <andy@warmcat.com> |