Wireshark mailing list archives
Re: About window scale option
From: Jeff Morriss <jeff.morriss.ws () gmail com>
Date: Wed, 29 Oct 2014 14:42:00 -0400
On 10/28/14 11:12, 徐鸿 wrote:
Hi , If the server does not support 'Window Scale' option, even the client send one packet with WS=256, I thought the real window size should be consider small than 64K. But I can see the 'Calculated window size' is larger that 64K on Wireshark1.12.1, is there something wrong ? the trace file is attached.
Well remember that on a given TCP connection there are 2 window sizes: that of the client and that of the server.
In this trace the client supports scaling but the server does not. Wireshark (at least the development version I just tried) correctly applied scaling to the client's window but not to the server's window:
> ./tshark -Y "ip.src==192.168.1.200" -Vr /tmp/window_scale_neg.pcapng |grep -i "window size" Window size value: 8192 [Calculated window size: 8192] Window size value: 64952 [Calculated window size: 16627712] <<< Scaling applied [Window size scaling factor: 256] Window size value: 64952 [Calculated window size: 16627712] [Window size scaling factor: 256] Window size value: 64222 [Calculated window size: 16440832] [Window size scaling factor: 256] Window size value: 64222 [Calculated window size: 16440832] [Window size scaling factor: 256] > ./tshark -Y "ip.dst==192.168.1.200" -Vr /tmp/window_scale_neg.pcapng |grep -i "window size" Window size value: 14600 [Calculated window size: 14600] Window size value: 11256 [Calculated window size: 11256] <<< No Scaling applied [Window size scaling factor: -2 (no window scaling used)] Window size value: 11256 [Calculated window size: 11256] [Window size scaling factor: -2 (no window scaling used)] Window size value: 11256 [Calculated window size: 11256] [Window size scaling factor: -2 (no window scaling used)] Window size value: 11256 [Calculated window size: 11256] [Window size scaling factor: -2 (no window scaling used)]
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Current thread:
- About window scale option 徐鸿 (Oct 28)
- Re: About window scale option Jeff Morriss (Oct 29)
- Re: About window scale option John Sullivan (Oct 29)
- Re: About window scale option Jeff Morriss (Oct 30)
- Re: About window scale option John Sullivan (Oct 29)
- Re: About window scale option Jeff Morriss (Oct 29)