netdev - Re: TCP socket receives strange packet

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Message-ID: <1413298852.17109.3.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Tue, 14 Oct 2014 08:00:52 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	"Yurij M. Plotnikov" <Yurij.Plotnikov@...etlabs.ru>
Cc:	netdev@...r.kernel.org,
	"Alexandra N. Kossovsky" <Alexandra.Kossovsky@...etlabs.ru>
Subject: Re: TCP socket receives strange packet

On Tue, 2014-10-14 at 18:09 +0400, Yurij M. Plotnikov wrote:
> Connected TCP socket receives packet without timestamps option which 
> exists in SYN, SYNACK and ACK. It is packet 4 in attached tcpdump output.
> 
> tcpdump output description: The host has address 10.208.10.1 (server) 
> and the peer host has address 10.208.10.2 (client).
> 
> Establishing connection: Timestamps option exists in SYN, SYNACK and ACK 
> (packets 1, 2 and 3 in attached file), so accepted socket should receive 
> packets only with timestamps option.

Can you point the RFC paragraph stating so ?

I have wondering if this behavior was correct some time ago, and could
not find a definitive answer.

RFC 1323 4.2.1 seems to suggest it is valid to accept a segment without
TS.

R1) If there is a Timestamps option in the arriving segment...


 There is no : Else drop the segment.



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