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TCP handshake question...

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barcaroller

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May 15, 2007, 6:31:44 PM5/15/07
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Client Server
-------- SYN J -------->
<--- SYN K, ACK J+1 ----
------- ACK K+1 ------->

During TCP connection establishment (above), the third segment is an ACK
from the client to the server. What is the sequence number in that segment?
Is it J or J+1 or 0 or some other value?


Jim Logajan

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May 15, 2007, 7:41:32 PM5/15/07
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Figure 7 in RFC0793 shows the same handshake, but with the additional
detail needed to answer your question. The sequence number in the third
segment is shown as J+1.

In general, any TCP segment containing a set FIN flag, a set SYN flag,
and/or data must advance the sequence number. Any segment void of all three
of those sequence-number-consuming aspects should contain the current
sequence number.

Justa Lurker

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May 15, 2007, 8:56:25 PM5/15/07
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Here is a question for you ...... when is the homework or takehome exam
due ?

chunhui

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May 16, 2007, 5:59:40 AM5/16/07
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barcaroller 写道:
I use tcpdump to capture a FTP link.and the result is J + 1.

--

chunhu...@163.com

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