Wireshark mailing list archives
Re: Ack number always equals 1
From: Richard Bejtlich <taosecurity () gmail com>
Date: Sat, 24 Oct 2009 15:42:15 -0400
On Sat, Oct 24, 2009 at 12:02 PM, Giovanni Parodi <giovanniparodi79 () yahoo it> wrote:
Good morning everyone, I'm a newbye in networking application and I trying to debug a strange problem that I have sending through TCP protocol some data from a DSP based system to a PC application The problem is that that the application running on PC disconnects after few packets, and so I used wireshark to debug the problem. It seems some packet get lost (I use a cross cable to connect the devices) and that the system isn't able to recover from such a problem. Furthermore I found out that Acknowledgement number generated by the DSP runnign the server appl always equals 1. Do you have any idea about some wrong setting that could generate such a behaviour? Giovanni
Hi Giovanni, 10.31.11.31 always sends relative TCP ACK 1 because 10.31.11.219 never sends any application layer data. 10.31.11.31 is always waiting for 10.31.11.219 to send its first byte of application layer data, but that never happens. 10.31.11.31 is the system that sends all the data in your conversation (23,109 bytes). The incorrect TCP checksum 0x2b52 could be added by the NIC as indicated by Wireshark's message (TCP Checksum offload?" or it could be hardcoded by the app on 10.31.11.219. Where did you perform the capture? Why do you think "the system isn't able to recover from such a problem"? I see the missing bytes of data are retransmitted such that 10.31.11.219 ACKs 49281 before 10.31.11.219 tears down the connection with a RST ACK. Sincerely, Richard ___________________________________________________________________________ Sent via: Wireshark-users mailing list <wireshark-users () wireshark org> Archives: http://www.wireshark.org/lists/wireshark-users Unsubscribe: https://wireshark.org/mailman/options/wireshark-users mailto:wireshark-users-request () wireshark org?subject=unsubscribe
Current thread:
- Ack number always equals 1 Giovanni Parodi (Oct 24)
- Re: Ack number always equals 1 Richard Bejtlich (Oct 24)
- Re: Ack number always equals 1 dan meyer (Oct 24)
- <Possible follow-ups>
- Re: Ack number always equals 1 Giovanni Parodi (Oct 26)