modification of sequence numbers in 802.11 header

Jouni Malinen jkmaline
Fri Apr 25 20:19:56 PDT 2003

On Fri, Apr 25, 2003 at 02:35:48PM -0700, Sumit Gwalani wrote:

> I wanted to know whether we can change the sequence number in the IEEE 802.11 header for management and data frames. If yes, can someone tell me as how this can be done. Is this possible with other dirvers or is this under the firmware control?

Sequence number field is under firmware control and I would assume that
the firmware would be overwriting this field and it would be impossible
to set it in the host driver. One reason for this is the fragmentation
of 802.11 frames which is (usually) done by firmware. However, I have
not tested this.

There is one special case, where the host driver would actually need to
be able to at least partially control sequence and fragment fields:
host-based WEP encryption. If a frame is fragmented, each fragment is
encryption separately and when doing the host-based WEP encryption, also
the fragmentation must be done in the host side. This would require
using the same sequence number and increasing fragment numbers in the
transmitted frames. I haven't written fragmentation code, so I haven't
yet been forced to figure out how to do this.

Jouni Malinen                                            PGP id EFC895FA

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