On Tue, Apr 5, 2016 at 4:34 PM, Grumbach, Emmanuel <emmanuel.grumbach@xxxxxxxxx> wrote: > On Tue, 2016-04-05 at 16:25 +0300, Gucea Doru wrote: >> On Tue, Apr 5, 2016 at 1:00 PM, Grumbach, Emmanuel >> <emmanuel.grumbach@xxxxxxxxx> wrote: >> > > >> > > Hello, >> > > >> > > I am trying to capture packets that are exchanged between an AP >> > > and a >> > > smartphone on the 5Ghz frequency. For generating traffic, I >> > > upload UDP >> > > traffic from a laptop PC towards the smartphone using iperf. >> > > >> > > The problem is that I can see _only_ the control frames like >> > > RTS/CTS, Block >> > > ACK, while the data packets are not captured. I uploaded the >> > > Wireshark >> > > capture files at [1] (located inside the folders whose name >> > > starts with 5Ghz). >> > >> > Most likely the packets on A band have a VHT preamble and your SKU >> > is 11N only. >> >> My card, Intel 7260 [1] supports 802.11 ac. So it should also >> support >> VHT, right? Is there any interface in user-space for checking after >> VHT? > > 7260 has several flavors. The one you have doesn't support VHT: >> iwlwifi 0000:04:00.0: Detected Intel(R) Dual Band Wireless N 7260 > > Dual Band means you have support for 5.2GHz, but Wireless N, means no > VHT. One of my colleagues had an Intel 7260 AC card so I repeated the experiments: - if I set the channel width to 20Mhz from the AP and the monitor interface using the command iw wlan0 set freq 5240 HT20+ I can see data frames and the Block ACKs for these frames; - if I set the channel width to 40Mhz from the AP and the monitor interface using the command iw wlan0 set freq 5240 HT40- I can see data frames and the Block ACKs for these frames; - If I set the channel width to 80Mhz from the AP I don't how to set up the monitor interface. I tried with iw wlan0 set freq 5240 HT40+ but it tells me that the argument is invalid. Is the iwlwifi driver capable of capturing data frames when the channel bonding is set to 80Mhz? > >> >> However, I noticed a "failure" message in dmesg: >> [ 4.030428] Intel(R) Wireless WiFi driver for Linux, in-tree: >> [ 4.030570] iwlwifi 0000:04:00.0: irq 37 for MSI/MSI-X >> [ 4.030760] iwlwifi 0000:04:00.0: Direct firmware load for >> iwlwifi-7260-10.ucode failed with error -2 >> [ 4.035509] iwlwifi 0000:04:00.0: loaded firmware version >> 25.228.9.0 op_mode iwlmvm >> [ 4.454772] iwlwifi 0000:04:00.0: Detected Intel(R) Dual Band >> Wireless N 7260, REV=0x144 >> [ 4.454825] iwlwifi 0000:04:00.0: L1 Disabled - LTR Enabled >> [ 4.455055] iwlwifi 0000:04:00.0: L1 Disabled - LTR Enabled >> [ 15.049933] iwlwifi 0000:04:00.0: L1 Disabled - LTR Enabled >> [ 15.050269] iwlwifi 0000:04:00.0: L1 Disabled - LTR Enabled >> >> Also, the maximum bit rate reported by iwconfig is 150 Mb/s, so my >> assumption is that the card can't enter into the 802.11 ac mode, it >> just stays into 802.11n. >> >> doru@doru-N551JK:~$ iwconfig wlan0 >> wlan0 IEEE 802.11abgn ESSID:"5_mptcp" >> Mode:Managed Frequency:5.24 GHz Access Point: >> C4:6E:1F:4B:10:A2 >> Bit Rate=150 Mb/s Tx-Power=22 dBm >> Retry short limit:7 RTS thr:off Fragment thr:off >> Power Management:on >> Link Quality=70/70 Signal level=-36 dBm >> Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 >> Tx excessive retries:0 Invalid misc:22 Missed beacon:0 >> >> >> [1] http://www.intel.com/content/www/us/en/wireless-products/dual-ban >> d-wireless-ac-7260-bluetooth-brief.html >> >> > Another option is that the traffic uses LDPC encoding and this >> > device doesn't support it. >> > >> > >> > > >> > > If I use the 2.4 frequency, all the frames are captured. I also >> > > uploaded the >> > > Wireshark packet traces for 2.4Ghz at [1] (located inside the >> > > folders whose >> > > name starts with 2.4 Ghz). >> > > >> > > Is this a known bug or am I doing something wrong? >> > > >> > > Additional details: >> > > Wi-Fi card: iwlwifi 0000:04:00.0: Detected Intel(R) Dual Band >> > > Wireless N 7260, >> > > REV=0x144 Firmware version: iwlwifi 0000:04:00.0: loaded firmware >> > > version >> > > 25.228.9.0 op_mode iwlmvm >> > > Traffic encryption: WPA & WPA2 Personal >> > > Setting up the card in wireless mode: >> > > ip link set dev wlan0 down >> > > iw wlan0 set type monitor >> > > ip link set dev wlan0 up >> > > iw wlan0 set freq 5240 >> > > >> > > [1] https://drive.google.com/open?id=0B5SBH08PU_Chek9rOHY0VkxFRUE >> > > >> > > Thank you, Doru -- 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
