Automatically Deploy Debian Firewalls with bash scripting

#!/bin/sh
# Debian FW deployer script
# Version 1.0

PROGNAME="$0"
VERSION="1.0"

# working directory for deployer process.
WORKDIR="/root"

# tasks left (this is updated every step to accommodate recovery during
# the deployer  process)
TASKS="./deploy-fw.tasks"

init_tasks() {
    # This function will write a new tasks file.
    # it's called from the main body of the script if a tasks file does not exist.
    cat > $TASKS<<EOS || return 1
nopasswd_ssh
add_pkgs
get__fw
configure_fw
set_hostname
EOS
    return 0
}

installer_splash() {
    echo "[+] Firewall deployer script starting..."
    echo "    Version: $VERSION"
    echo
    return 0
}

nopasswd_ssh() {
    # disable passwd auth on SSH
    echo "[+] Disabling password authentication for SSH... "
    perl -pi -e 's/^PasswordAuthentication yes/PasswordAuthentication no/g' /etc/ssh/sshd_config
    perl -pi -e 's/^#PermitRootLogin yes/PermitRootLogin without-password/g' /etc/ssh/sshd_config
    /etc/init.d/ssh restart
    return 0
}

add_pkgs() {
    PKGS="libssl0.9.7 exim4 iproute ethtool tcpdump snmpd pciutils less python"
    echo "[+] Installing packages: $PKGS... "
    apt-get -y install $PKGS || return 1
    return 0
}

get__fw() {
    echo "[+] Downloading  packages... "
    # download the latest version of the  Client firewall package.
    wget --no-check-certificate http://www.yoursite.com/fw.tgz -O /tmp/firewall.tgz || return 1
    # get the latest firewall.trusted file
    wget --no-check-certificate http://www.yoursite.com/firewall.trusted -O /tmp/firewall.trusted || return 1
    # unpack firewall scripts
    tar --no-same-owner --no-same-permissions --directory / -zxvf /tmp/firewall.tgz || return 1
    mv /tmp/firewall.trusted /etc/network/firewall.trusted || return 1
    chmod +x /etc/network/firewall.trusted || return 1
    rm /tmp/firewall.tgz || return 1
    echo "done."
    return 0
}

configure_fw() {
    # time to configure the  FW
        KAD=/etc/keepalived/keepalived.conf
    FW=/etc/network/firewall
    RELOAD=/etc/network/reload.sh
    HOSTS=/etc/hosts
    INTERFACES=/etc/network/interfaces
    NRPE=/etc/nagios/nrpe_local.cfg
    EXIM=/etc/exim4/update-exim4.conf.conf
    CONFIGURE_FW=/etc/network/configure-fw.pl
    echo "[+] Configuring Firewall..."
    perl $CONFIGURE_FW
    if [ $? -ne 0 ]; then
        echo "[!] ERROR: Configuring firewall script failed!"
        return 1
    fi
    echo "[+] Moving files into place..."
    rm ${KAD}-template || return 1
    rm ${FW}-template || return 1
    rm ${RELOAD}-template || return 1
    rm ${CONFIGURE_FW}
    mv ${HOSTS}.new ${HOSTS} || return 1
    mv ${INTERFACES}.new ${INTERFACES} || return 1
    mv ${NRPE}.new ${NRPE} || return 1
    mv ${EXIM}.new ${EXIM} || return 1
    chmod 700 ${FW}
    chmod 700 ${RELOAD}
    update-rc.d keepalived defaults || return 1
    update-exim4.conf || return 1
    # for compatibility
    echo "[+] Generating RSA Keys"
    ssh-keygen -t rsa -f ~/.ssh/id_rsa -P '' || return 1

    return 0
}
clean_up_and_reboot() {
    # remove:
    # -- temp task file
    rm $TASKS
    # remove self from .bashrc
    if [ -f /root/.bashrc.orig ]; then
        mv /root/.bashrc.orig /root/.bashrc
    fi
    if [ -z /root/.bashrc ]
    then
        rm /root/.bashrc
    fi
    # delete self
    rm $0
    # and reboot.
    echo "[+] Please reboot system."
    #reboot -n
    exit 0
}

debug_quit() {
    # hard exit the script in appropriately referenced files
    # so that no reboot happens.
    echo "debug_quit seen in tasks file, exiting."
    exit 0
}

set_hostname() {
    echo "[+] Setting FW hostname... "
    echo `hostname` > /etc/hostname
    echo `hostname` > /etc/mailname
    echo "done."
    return 0
}

usage() {
    echo "[+] Usage: $PROGNAME"
    echo
    return 0
}

###############################
### MAIN SCRIPT STARTS HERE ###
###############################

# installer_splash
installer_splash

# fix working dir.
cd $WORKDIR

# does our installer file exist? if not, initalize it.
if [ ! -f $TASKS ]
then
    echo "[+] No task file found, installation will start from beginning."
    init_tasks
    if (($? != 0))
    then
        echo "[!] ERROR: Cannot create tasks file. Installation will not continue."
        exit 1
    fi
else
    echo "[+] Tasks file located - starting where you left off."
fi

# start popping off tasks from the task list and running them.
# pop first step off of the list
STEP=`head -n 1 $TASKS`
while [ ! -z $STEP ]
do
    # execute the function.
    echo -e "nn###################################"
    echo "[+] Running step: $STEP"
    echo -e "###################################nn"
    $STEP
    if (($? != 0))
    then
        # command failed.
        echo "[!] ERROR: Step $STEP failed!"
        echo "    Installation will now abort - you can pick it up after fixing the problem"
        echo
        exit 1
    fi
    # throw up a newline just so things don't look so crowded
    echo
    # remove function from function list.
    perl -pi -e "s/$STEPn?//" $TASKS || exit 1
    STEP=`head -n 1 $TASKS`
done

# clean_up_and_reboot
echo "[+] Installation finished - cleaning up."
clean_up_and_reboot

# script is done now - termination should happen with clean_up_and_reboot.
echo "[!] Should not be here!"
exit 1