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From: Leendert van Doorn (leendertparamecium.org)
Date: Mon May 07 2001 - 20:53:29 CDT
# I don't know what the ioctl is supposed for, so random
My ioctl's do essentially the same thing as Javier's /proc interface.
Either interface will do.
# No, what you want to do is to pass it in the skbuff. That's
# the only logical way to pass this data up without getting crazy.
# You have quite a bit of freedom with skbuffs. Basically, you
# can prepend any data you want before the 802.3 header and hide it
# (with skb_reserve or skb_put). This is the way I would do it.
# skbuff skb->head/skb->data
# | |
# V V
# | PLCP | 802.11 | 802.3 | IP | TCP | ...
# <hope everybody is using fixed fonts>
Exactly, this is how I pass things up. The 802.3 header is actually an
LLC header, monitor mode will give you the raw 802.11 packets.
# After, you just need to communicate to the utility the offsets
# in the packet. And, as you still have 802.3 headers, you don't break
# TCP/IP or tcpdump (very important !!!).
I modified libpcap. I didn't make it work for tcpdump (this is a tcpdump
problem not a libpcap problem), instead I used ethereal/tethereal. It
has support for 802.11 packet decoding.
# By the way : I don't believe anybody need to have the RSSI
# value of every packet. iwspy is good enough for most use. I also don't
# think that the 802.11 header is that useful, a standard tcpdump is
# already plenty good enough for me (when it works). Bah...
Depends on what you want to do. I need to look at the data without being
authenticated or knowing the WEP keys.
# > I'm not sure if it's better to drop the packet or to signal the
# > application about the problem.
That's why I pass up the entire aironet specific header which has the rssi
and plcp fields, but I agree it is nicer to come up with some driver
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