Wireshark-users: Re: [Wireshark-users] TCP sequence number

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From: Guy Harris <guy@xxxxxxxxxxxx>
Date: Tue, 22 Dec 2009 18:55:55 -0800
On Dec 22, 2009, at 6:29 PM, Rayne wrote:

> I would like to know how Wireshark reads the sequence number. I have a packet with the Sequence number displayed as 3273, but the corresponding bytes are "2e b2 cf 43". How did Wireshark get 3273 from 2e b2 cf 43?

By fetching the bytes in question in network byte order, and then subtracting the initial sequence number for the TCP connection from it.

(I.e., by default, it displays relative sequence numbers, not absolute sequence numbers.)