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Wireshark-users: Re: [Wireshark-users] Help with Output "TCP Dup ACK3#2 1320 > 22 ACK

From: "ronnie sahlberg" <ronniesahlberg@xxxxxxxxx>
Date: Tue, 22 May 2007 21:34:51 +0000
also check the duplex settings in case you have a duplex mismatch.


On 5/22/07, Mike Ciccone <mciccone@xxxxxxxxx> wrote:
Martin/Stephen
Thanks for the answers... I'm on travel at the moment and won't be back to
look at this problem until Monday.  I did check for ACL's and Firewalls
Blocks but I am not finding any... I'll keep looking.

Thanks,

Michael Ciccone
Network Engineer
eToys Direct, Inc.
Office:  303-226-8617
Cell:  720-299-1573
Fax:  303-226-8600
http://www.etoys.com



"Visser, Martin" <martin.visser@xxxxxx>
Sent by: wireshark-users-bounces@xxxxxxxxxxxxx
05/21/2007 06:05 PM
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Subject
Re: [Wireshark-users] Help with Output "TCP Dup ACK3#2 1320 > 22 ACK






Duplicate ACKs are fairly common, so they don't always indicate a problem.
During normal congestion you will receive duplicate ACKs if the far end
has not received a TCP segment it believes it should have. It also can be
used to keep alive a connection.

However if you get dup ACKs consistently at the start of a connection it
might mean that there is some sort of firewall ACL blocking traffic. As
Stephen said, it is important to know where this occurs during the 3 way
handshake at the beginning of a connection or later on.

Martin Visser

Technology Consultant
Consulting & Integration
Technology Solutions Group - HP Services

410 Concord Road
Rhodes NSW  2138
Australia

Mobile: +61-411-254-513
Fax: +61-2-9022-1800
E-mail: martin.visserAThp.com

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recipient, please notify HP immediately by return email and then delete
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information in it.




From: wireshark-users-bounces@xxxxxxxxxxxxx
[mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Mike Ciccone
Sent: Saturday, 19 May 2007 7:57 AM
To: wireshark-users@xxxxxxxxxxxxx
Subject: [Wireshark-users] Help with Output "TCP Dup ACK3#2 1320 > 22 ACK


Hello,
I am having a problem with SSH.  I can ssh from some server but not
others.  I verified that there are no access-lists blocking from doing
this.  When I ran Wireshark on my pc and tried to ssh to the server I get
the following line that could be telling me what the problem is. However,
I don't understand it and was hoping some out there could explain it to
me.

Here is the line:
[TCP Dup ACK 3#2] 1320 > 22 [ACK] Seq=1 Ack=1 win=65535 Len=0

Does this mean anything to anyone?  I'm guessing my problem lies here.  If
I ssh to a server that works... I don't see this line

Thanks

Mike C. _______________________________________________
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