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

From: Mike Ciccone <mciccone@xxxxxxxxx>
Date: Tue, 22 May 2007 07:16:59 -0600

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
Please respond to
Community support list for Wireshark <wireshark-users@xxxxxxxxxxxxx>

To
"Community support list for Wireshark" <wireshark-users@xxxxxxxxxxxxx>
cc
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

This email (including any attachments) is intended only for the use of the individual or entity named above and may contain information that is confidential, proprietary or privileged. If you are not the intended recipient, please notify HP immediately by return email and then delete the email, destroy any printed copy and do not disclose or use the 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.
_______________________________________________
Wireshark-users mailing list
Wireshark-users@xxxxxxxxxxxxx
http://www.wireshark.org/mailman/listinfo/wireshark-users