Re: Unexpected Acknowledgement / Stalled Connections

From: Parag Warudkar
Date: Sun Feb 04 2007 - 17:57:19 EST


On 2/4/07, Parag Warudkar <parag.warudkar@xxxxxxxxx> wrote:
I am running 2.6.20 and have trouble with stalled connections. For
instance, if I try to download a debian ISO image using wget, the
connection runs fine for few seconds and then stalls for ever.

In my router logs I see a ton of messages like the below -

[INFO] Sun Feb 04 17:22:03 2007 Blocked incoming TCP packet from
192.168.0.174:34090 to 130.239.18.138:80 with unexpected
acknowledgement 3269301836 (expected 3269343453 to 3269408989)

Where 192.168.0.174 is my laptop running FC6 and kernel 2.6.20 and
130.239.18.138 is whatever cdimage.debian.org resolves to atm.

What's going on here? Any TCP/IP tunable that I can set/turn on/off to
prevent this from happening?

Turning tcp_sack off seems to cure it. Turning it on again makes the
connections stall. Seems like the D-Link router doesn't like the SACKs
linux sends?

Parag
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