[clug] Treason uncloaked!

Tony Breeds tony at bakeyournoodle.com
Wed Sep 20 23:46:51 GMT 2006

On Thu, Sep 21, 2006 at 09:29:49AM +1000, Michael James wrote:
> Quite frequently /var/log/messages offers this intriguing entry:
> kernel: TCP: Treason uncloaked!
> 	Peer shrinks window
> 	3222363773:3222384045. Repaired.
> As you can see from the IP, it's a private subnet,
>  it's my machine that's being complained about.
> What's it likely to be?  (curiosity)

The comment above the printk() says:

/* Receiver dastardly shrinks window. Our retransmits
 * become zero probes, but we should not timeout this
 * connection. If the socket is an orphan, time it out,
 * we cannot allow such beasts to hang infinitely.
> Is it anything I should worry about?

It's the reciever that's causing the problem so talk to them.
What OS is the reciever?

> If it is, what could I do to fix it?

If you can trigger it at will, try tuning off window scaling.

echo 0 > /proc/sys/net/ipv4/tcp_window_scaling

To see if that fixes things.

Yours Tony

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