Messages in this thread | | | Date | Fri, 02 Sep 2005 14:45:37 +0900 (JST) | From | Noritoshi Demizu <> | Subject | Re: Possible BUG in IPv4 TCP window handling, all recent 2.4.x/2.6.x kernels |
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> > Since the TCP Window Scale options are exchanged, > > the window size field contains shifted value except SYNs. > > Be careful, tcpdump may be tracking the window scale and reporting > scaled values. Seems unlikely since with a window scale of 2, and odd > window size would be impossible.
I am sorry if tcpdump tracks the window scale option. But I think it is unlikely, because there are odd window sizes, as you pointed out.
By the way, if tcpdump does not track the window scale option, the right edge (ack + real win) does not change between the following two ACKs.
> 11:34:54.337167 10.2.20.246.33060 > 10.2.224.182.8700: . ack 84402527 win 15340 <nop,nop,timestamp 226080473 99717814> (DF) (259 ACKs are omitted here) > 11:34:54.611769 10.2.20.246.33060 > 10.2.224.182.8700: . ack 84454467 win 2355 <nop,nop,timestamp 226080721 99717841> (DF)
The first line is the 37th ACK and the second line is the 295th ACK.
ACK#37: ack=84402527 win=15340 right_edge=84463887 (= ack + win * 4) ACK#295: ack=84454467 win=2355 right_edge=84463887 (= ack + win * 4)
And all ACKs later than ACK#295 has win=2355 (2355*4=9420).
This may be a hint. But, sorry, I do not know the internal of Linux TCP.
Regards, Noritoshi Demizu - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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