Scapy failing to transmit 802.11 packet, TX dropped counter incrementing

ianling commented 5 years ago

Environment

Scapy version: scapy 2.4.3 (latest version from pip3 at time of writing)
Python version: 3.5.3
Operating System: Debian stretch 4.19.0-0.bpo.5-amd64 #1 SMP Debian 4.19.37-4~bpo9+1 (2019-06-19) x86_64 GNU/Linux
Wireless Adapter: Alfa AWUS036AC using aircrack's rtl8812au v5.2.20 driver from git

I'm finding that when I attempt to send any 802.11 packet, sendp() executes without any errors, but in ifconfig, I see the TX dropped counter incrementing. I am also unable to sniff the packet from other nearby hosts listening on the same channel, so the packet is not making it past the kernel.

interface = "wlan2"
sa = "aa:bb:cc:dd:ee:ff"
da = "ae:ab:bc:8c:0b:07"
bssid = "ae:ab:bc:8c:0b:07"
p = RadioTap()/Dot11(addr1=da, addr2=sa, addr3=bssid)/Dot11ProbeReq()
sendp(p, iface=interface)

Am I missing something obvious?

edit: my wlan2 interface was not in monitor mode. I changed it to monitor mode, and the counter stopped incrementing. However, I am still unable to see the packets in the air from another device monitoring that channel. I do see the packets if I use tcpdump on the same host that is running Scapy.

gpotter2 commented 5 years ago

You can try turning libpcap mode on with conf.use_pcap = True then add monitor=True to both your sniffs and sendp calls

ianling commented 5 years ago

If I set conf.use_pcap=True, I am able to use sendp without monitor=True. It still does not appear to actually work though.

If I do both conf.use_pcap=True and monitor=True, then I get the following error:

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/usr/local/lib/python3.5/dist-packages/scapy/sendrecv.py", line 335, in sendp
    socket = socket or conf.L2socket(iface=iface, *args, **kargs)
  File "/usr/local/lib/python3.5/dist-packages/scapy/arch/pcapdnet.py", line 317, in __init__
    monitor=monitor)
  File "/usr/local/lib/python3.5/dist-packages/scapy/arch/pcapdnet.py", line 262, in <lambda>
    open_pcap = lambda *args, **kargs: _PcapWrapper_winpcap(*args, **kargs)
  File "/usr/local/lib/python3.5/dist-packages/scapy/arch/pcapdnet.py", line 208, in __init__
    raise OSError("Could not activate the pcap handler")
OSError: Could not activate the pcap handler

I have installed libpcap0.8 (this is the libpcap package Debian stretch offers) and pcapy (via pip).

ianling commented 5 years ago

I'm thinking there's probably some driver issues at play here. I can pretty consistently get kernel panics when testing stuff with the aircrack suite. I will try some other drivers.

guedou commented 5 years ago

Please reopen the issue if this is Scapy related.

secdev / scapy

Scapy failing to transmit 802.11 packet, TX dropped counter incrementing #2230

Environment