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#!/bin/sh -e
#
# byobu-classroom - set up a byobu-classroom shared screen session,
# with one writer and many guest readers
#
# Copyright (C) 2011 Canonical Ltd.
#
# Authors: Dustin Kirkland <kirkland@byobu.co>
#
# 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, version 3 of the License.
#
# 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 <http://www.gnu.org/licenses/>.
PKG="byobu"
. "/usr/lib/$PKG/include/shutil"
usage() {
echo
echo "Usage: $0 [HOSTUSER [GUESTUSER]]"
echo
echo "If HOSTUSER is unspecified, \$SUDO_USER [$SUDO_USER] is used."
echo "If GUESTUSER is unspecified, 'guest' is used."
echo
}
[ -n "${1}" ] && HOSTUSER="${1}" || HOSTUSER="$SUDO_USER"
[ -n "${2}" ] && GUESTUSER="${2}" || GUESTUSER="guest"
# Ensure that our host user exists
while ! id "$HOSTUSER" >/dev/null 2>&1; do
error "Host user does not exist"
id "$HOSTUSER"
usage
exit 1
done
# Ensure that there is not already a guest user
while id "$GUESTUSER" >/dev/null 2>&1; do
echo
info "To operate in classroom mode, we must create the [$GUESTUSER] user."
info "There is already a [$GUESTUSER] user on this system."
echo
echo "Do you want to permanently delete the [$GUESTUSER] user now? [y/N]: "
c=$(head -n1)
case "$c" in
y|Y)
deluser --force --remove-home "$GUESTUSER"
info "[$GUESTUSER] user deleted"
;;
*)
error "[$GUESTUSER] user still exists"
id "$GUESTUSER"
;;
esac
done
# Ensure that our new guest exists
while ! id "$GUESTUSER" >/dev/null 2>&1; do
echo
info "To operate in classroom mode, we must create the [$GUESTUSER] user."
echo
echo "Do you want to create the [$GUESTUSER] user now? [y/N]: "
c=$(head -n1)
case "$c" in
y|Y)
# Hardcode password to "guest"
cryptpw="ubXWbZ4Ffn.mg"
useradd -m -s /bin/bash -p "$cryptpw" "$GUESTUSER"
touch "/home/$GUESTUSER/.screenrc"
chown -R root:root /home/$GUESTUSER
info "Guest user created"
;;
*)
error "[$GUESTUSER] user does not exist"
id "$GUESTUSER"
;;
esac
done
# Ensure the correct permissions on screen binary
screen=$(which screen)
while [ $(stat -c%a "$screen") != "6755" ]; do
echo
ls -alF "$screen"
info "To operate in classroom mode, $screen must have 6755 permissions."
printf "Do you want to set this now? [y/N]: "
c=$(head -n1)
case "$c" in
y|Y)
dpkg-statoverride --add root root 6755 "$screen"
info "Updated $screen"
echo
info "To revert this later, run:"
info " sudo dpkg-statoverride --remove $screen"
;;
*)
error "Incorrect permissions on $screen"
ls -alF "$screen"
;;
esac
done
# Ensure correct permissions on screen's run directory
service screen-cleanup start
# Ensure that SSH configuration is correct
while [ $(grep -c "#byobu-classrom" /etc/ssh/sshd_config) != "4" ]; do
echo
info "To operate in classroom mode, SSH must:"
info " a) have password authentication enabled"
info " b) disable TCP Forwarding"
info " c) force the guest user's login command"
echo
printf "Do you want to set these now? [y/N]: "
c=$(head -n1)
case "$c" in
y|Y)
$BYOBU_SED -i -e '/#byobu-classroom/d' /etc/ssh/sshd_config || true
echo "
PasswordAuthentication yes #byobu-classroom
AllowTcpForwarding no #byobu-classroom
Match User $GUESTUSER #byobu-classroom
ForceCommand exec screen -x $HOSTUSER/byobu-classroom #byobu-classroom
" >> /etc/ssh/sshd_config
echo
info "To revert this later, run:"
info " sudo sed -i -e '/#byobu-classroom/d' /etc/ssh/sshd_config"
;;
*)
error "Incorrect sshd configuration"
;;
esac
done
service ssh restart
# Launch the session detached
su -l $HOSTUSER -c 'byobu -c /usr/share/byobu/profiles/classroom -d -m -S byobu-classroom -t shell bash'
info "Byobu classroom setup successfully!"
echo
info "Please tell your guests to:"
info " ssh -C $GUESTUSER@$(hostname)"
info "with password=guest"
echo
info "As the host, you should connect with:"
info " ssh -C $HOSTUSER@$(hostname)"
info "to control the session"
echo
# vi: syntax=sh ts=4 noexpandtab
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