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How to log free space in the TCP receiver window?

asked 2018-06-08 09:53:13 +0000

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Hi, I want to monitor the free space in the receiver window and the field "receiver window" on wireshark shows the size of the receiver window. As the data is queued in the window until its passed to the application layer, to my understanding, the instantaneous receiver window (filled up window size or remaining size) should be varying depending on the throughput of the connection. Is there a tool or syscall in Linux to monitor the changes to the receiver window in live?

I experimented with varying receiver window (small size), but the wireshark shows a constant window size.

Thanks in advance!

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answered 2018-06-09 10:01:58 +0000

updated 2018-06-09 10:59:55 +0000

grahamb gravatar image

You can use advertised window size, bytes_in_flight and push_bytes_sent for this kind of analysis. Or you can use the tcpstream graph for this kind of analysis, too.

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I think the question is more about a Linux tool that shows the parameter values of the TCP stack of the OS

Jasper gravatar imageJasper ( 2018-06-10 22:09:07 +0000 )edit

O.K. Then maybe this linux tool can help:

"ss" - another utility to investigate sockets

cubic wscale:10,10 rto:222 rtt:21.105/19.23 ato:40 mss:65483
*cwnd:10* send 248.2Mbps lastsnd:444202283 lastrcv:444202284 lastack:444202243 pacing_rate
496.4Mbps **rcv_space:65495**


  cubic wscale:10,10 rto:201 rtt:0.713/0.472 ato:40 mss:32768
        *cwnd:10* send 3676.6Mbps lastsnd:444197578 lastrcv:444197578 lastack:680 pacing_rate 7349.4Mbps rcv_rtt:3138.75 **rcv_space:65483**
Christian_R gravatar imageChristian_R ( 2018-06-11 07:28:12 +0000 )edit

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Asked: 2018-06-08 09:53:13 +0000

Seen: 44 times

Last updated: Jun 09