cd /tmp; curl https://www.kernel.org/pub/linux/utils/util-linux/v2.25/util-linux-2.25.tar.gz | tar -zxf-; cd util-linux-2.25;
sudo apt-get install autopoint autoconf libtool automake
./configure --without-python --disable-all-programs --enable-nsenter --without-ncurses
make nsenter; cp nsenter /usr/local/bin