linux-kernel - Re: strange Mac OSX RST behavior

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Date:	Fri, 1 Jul 2016 17:04:41 +0100
From:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
To:	Jason Baron <jbaron@...mai.com>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	davem@...emloft.net, eric.dumazet@...il.com
Subject: Re: strange Mac OSX RST behavior

> On Mac OSX 10.11.5 (latest version), we have found that when tcp
> connections are abruptly terminated (via ^C), a FIN is sent followed
> by an RST packet. The RST is sent with the same sequence number as the
> FIN, and thus dropped since the stack only accepts RST packets matching
> rcv_nxt (RFC 5961). 

The Linux behaviour appears to be correct, and accepting a broken FIN is
most definitely a bad idea, it has a very different effect to a FIN
because there can be data going the other direction and a FIN is a one
way close

Alan