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Date: Wed, 20 Sep 2017 12:53:02 +0200
From: =?UTF-8?Q?Micha=C5=82_J=C4=99drzejczak?= <mj@bsdops.com>
To: FreeBSD Net <freebsd-net@freebsd.org>, freebsd-question@freebsd.org
Subject: tcp_extensions="NO"
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Hello folks
What is reason to set in rc.conf that extensions?
tcp_extensions="NO"

When that disable old and obsolete rfc 1323 ? 
https://tools.ietf.org/html/rfc1323

Source from /etc/defaults/rc.conf:
tcp_extensions="YES"            # Set to NO to turn off RFC1323 
extensions.

-- 
Pozdrawiam
Michał Jędrzejczak