From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: BSD 4.2 style TCP keepalives
Date: Wed, 06 Jan 2010 16:59:33 -0800 (PST)
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=46rom: "Ilpo J=E4rvinen" <ilpo.jarvinen@helsinki.fi>
Date: Thu, 7 Jan 2010 02:34:51 +0200 (EET)

> On Wed, 6 Jan 2010, David Miller wrote:
>=20
>> 3) tcp_data_queue() should make it to, and hit, this conditional:
>>=20
>> 	if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) {
>>=20
>>    which will schedule an ACK the same exact way we would if
>>    tcp_sequence() rejected the sequence range.
>>=20
>> So it's a mystery why we aren't responding to Windows 2000's
>> BSD 4.2 style zero window probes.
>>=20
>> Can someone please validate my analysis?
>=20
> In 3) I don't see why we'd hit that one as peer's snd_una+1 would be=20
> larger than rcv_nxt.

Peer constructs keepalive packet using sequence [snd.una-1,snd.una],
both of which are <=3D rcv_nxt