tcpdump mailing list archives

Re: pcap_inject troubleshooting


From: David Murray <30179198 () student murdoch edu au>
Date: Tue, 13 Jan 2009 14:05:39 +0900

Quoting Guy Harris <guy () alum mit edu>:



I'm assuming your wired NICs are Ethernet NICs; the maximum payload
size for Ethernet is 1500 bytes.

The maximum payload size for IEEE 802.11 is 2304 bytes, at least
according to IEEE 802.11-1999:

        6.2.1.1.2 Semantics of the service primitive

                ...

        The data parameter speciļ¬es the MSDU to be transmitted by the MAC
sublayer entity. For IEEE 802.11, the
length of the MSDU must be less than or equal to 2304 octets.

1500 < 1552 < 2304.


Good point. However, the packets that I am capturing are going
end-to-end and they are being replayed to the same receiver.
Subsequently, the payload size of the frame should be less than 1500.

Do you think it is possible that when I capture and replay these
packets pcap is appending new headers to the frame without removing the
old hence pushing the packet size above 1514 bytes for Ethernet?


-
This is the tcpdump-workers list.
Visit https://cod.sandelman.ca/ to unsubscribe.


Current thread: