Wireshark-users: Re: [Wireshark-users] Odd tcp establishment sequence?
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From: Allen Lee <a11en1ee@xxxxxxxxxxx>
Date: Tue, 1 May 2018 20:38:01 +0000 (UTC)
The second SYN by the client is because the server didn't respond before the retransmission timer expiry.  There are a couple of reasons, the server is busy, network congestion, or circuit issues. If you haven't try it yet, install a protocol analyzer at the F5. .




On Tuesday, May 1, 2018 10:31 AM, Mohamed Lrhazi <lrhazi@xxxxxxxxx> wrote:


Hello,

am trying to debug why often times, my ssh client timeout trying to establish connection to an ssh server (F5 device)... 

Often times, I see a SYN sent twice, then server responding with an ACK, then an SYN/ACK, then my client sends RST.

Other times, I see several SYN re-transmits, then ACK response, then SYN/ACK, then ACK from client and connection getting established!

This is all not very normal, right? especially the ACK in response to a SYN? that should cause clients to fail to continue establishing a connection, right?

Thanks a lot for your input, I know this is not wireshark issue!

Mohamed,
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