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Date: Wed, 12 Feb 2014 23:24:59 +0400
From: Gleb Smirnoff <glebius@FreeBSD.org>
To: Robert Simmons <rsimmons0@gmail.com>
Subject: Re: PF in FreeBSD 10.0 Blocking Some SSH
Message-ID: <20140212192459.GD26785@FreeBSD.org>
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On Mon, Jan 27, 2014 at 10:22:30PM -0500, Robert Simmons wrote:
R> > On Sun, Jan 26, 2014 at 06:19:34PM -0500, Robert Simmons wrote:
R> > R> Over the course of a few hours there are a handful of SSH packets that
R> > R> are being blocked both in and out. This does not seem to affect the
R> > R> SSH session, and all the blocked packets have certain flags set [FP.],
R> > R> [R.], [P.], [.], [F.]. The following is my ruleset abbreviated to the
R> > R> rules that apply to this problem:
R> > R>
R> > R> ext_if = "en0"
R> > R> allowed = "{ 192.168.1.10 }"
R> > R> std_tcp_in = "{ ssh }"
R> > R> block in log
R> > R> block out log (user)
R> > R> pass in quick on $ext_if proto tcp from $allowed to ($ext_if) port
R> > R> $std_tcp_in keep state
R> > R>
R> > R> Why are those packets being blocked?
R> >
R> > Do I understand you correct that the ssh sessions work well, but you
R> > see blocked packets in the pflog?
R> 
R> Yes, this is correct. I have not seen this in the logs since
R> yesterday, so it may have been a network issue.

That could be stray retransmits of data that already been received
and acknowledged. pf keeps track of sequence numbers in tcp connections
flowing through it.

-- 
Totus tuus, Glebius.