On Monday, October 29, 2012 01:44:35 AM David H. Lynch Jr. wrote: > I would be happy with any other means of forcing the transmission of an > HT40 packet. RADIOTAP injection is just the only means I am aware of to > do so - and from what I am gathering not an effective one. Depends, hostapd uses it a lot. But it doesn't need to do any HT40 transmissions. I know that other people had similar issues as well, but with ath9k. AFAICT, someone posted a patch on ath9k-devel which made it possible to force the rate of outgoing frames, but you'll have to google that. > > The sending part is not. AFAICT you'll have to start by declaring > > and defining a new radiotap rate info element (IEEE80211_RADIOTAP_RATE > > can only handle the bit rate and that is not enough). Then you have > > to add a parser which translate the rate info in the radiotap header > > into mac80211 ieee80211_tx_rate and tell mac80211 to bypass rate_ctrl > > tx handler in this case so the info won't be overwritten again... > > And finally you'll have to add a header with this new rate info element > > into the radiotap header of all the frames you send through the raw > > monitor interface. > > > A proof-of-concept should be easily doable within a day. But getting > > this new radiotap to be part of the spec will take longer ;) > with my level of Radiotap/mac80211/wifi knowledge this is much more > than a days work. How do you know? The parser code is in ieee80211_parse_tx_radiotap and all you would have to do is to extend it with another case and tell mac80211 not to overwrite the rate in ieee80211_tx_h_rate_ctrl when it was set by ieee80211_parse_tx_radiotap. > Any other ideas for forcing transmission of an HT40 packet? > What If I omit radiotap and just send an ieee80211 raw packet? Sure, you can that. Just get a skb. Fill it with the data you want to send and initialize the ieee80211_tx_control and ieee80211_tx_info (in skb's cb) and call carl9170_op_tx. If you want it to be done by the fw: Just reserve some space in ar9170_dma_memory and fill out the tx header carl9170_tx_superdesc (header declarations and definitions are in include/shared/wlan.h) and call wlan_tx_fw. > >> So I have been using airmon, wireshark, .... > >> But i need to be able to send and verify an HT40 packet by some > >>somewhat > >> normal means, to assure myself that my receiving end wireshark > >> hardware/driver/software combination can tell me what i need to > >know. > >Well, you should be able to verify if your device picks up HT40 frames > >easily. All you need is any busy 11n network with a 11n AP and a 11n > >client. Just setup the receiver device (correct channel and HT40+/- > >setting) and start listening. > still not easy - no 80211n AP's just alot of AR9170's. > I guess I am going to be looking for a cheap 80211n AP. if you have two devices to spare you can setup one as AP and the other as a client [this can be done on the same machine if you have network namespaces]. AP: # hostapd hostapd.conf --- hostapd.conf --- interface=wlanX driver=nl80211 ssid=TESTN hw_mode=g channel=1 wmm_enabled=1 ieee80211n=1 ht_capab=[HT40+] --- hostapd.conf --- client: # iw dev wlanY connect TESTN --- Then assign both AP and client ip addresses in the same subnet and ping each other. Regards, Chr -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
