Are you sure? It's in the universe repo of Ubuntu and not restricted or
multiverse. If you go to
http://www.realtek.com.tw/downloads/downloadsview.aspx?langid=1&pnid=13&pfid=5&level=5&conn=4&downtypeid=3&getdown=false#2
for r8168-8.040.00.tar.bz2 and take a look at the source code you will see:
################################################################################
#
# r8168 is the Linux device driver released for Realtek Gigabit Ethernet
# controllers with PCI-Express interface.
#
# Copyright(c) 2014 Realtek Semiconductor Corp. All rights reserved.
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 2 of the License, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
# more details.
#
# You should have received a copy of the GNU General Public License along
with
# this program; if not, see .
#
# Author:
# Realtek NIC software team
# No. 2, Innovation Road II, Hsinchu Science Park, Hsinchu 300, Taiwan
#
################################################################################
